# Any heavier riders on full carbon clinchers?



## thisisthebeave (Aug 30, 2015)

I guess what I'm worried about is blowouts due to heat when descending. Most of my riding is pretty flat but sometimes I go on some very hilly rides. Also mildly concerned with crosswinds but I've read that at least the 404's do pretty well in crosswinds for their depth.

I'm 6'6" 235 currently on Dura Ace C35's and I'm contemplating Zipp 404, Enve SES 6.7, or Enve SES 4.5.


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## mikerp (Jul 24, 2011)

As was posted in the other thread, while you posted there that you aren't concerned with spoke count you should be. While you have been getting by on the other bikes and wheels you aren't in the optimum area for your weight.
I wouldn't worry about the heat issue at this point from your description you aren't descending mountains.


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## thisisthebeave (Aug 30, 2015)

mikerp said:


> As was posted in the other thread, while you posted there that you aren't concerned with spoke count you should be. While you have been getting by on the other bikes and wheels you aren't in the optimum area for your weight.
> I wouldn't worry about the heat issue at this point from your description you aren't descending mountains.


"sometimes I go on some very hilly rides" ... my rides are either very flat or pretty steep... 10-15% grades where you are (or at least I am) on the brakes a little bit the whole way down.

My road wheels are 16f/21r spokes but the spokes are very big, about twice as wide as a CX Ray, so I'm sure that's what permits the low count. My wheelset before that had 18f/24r (Bontrager Race Lite) with DT Comp spokes on shallow alu rims and those are fine too. My mountain bike wheels are Roval Fattie SL's with a massive 35mm wide carbon rim so I'm sure that's what permits the low spoke count.

I guess where I'm going with this is that the ~60mm deep Zipp/ENVE rims mean shorter spokes, which mean less flex... so I'm just not worried about it. If the Dura Ace wheels are working fine for me with 16/21, I'm sure an ENVE wheel with 20/24 with a bigger, and presumably stiffer, rim will be fine.


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## ericm979 (Jun 26, 2005)

thisisthebeave said:


> "sometimes I go on some very hilly rides" ... my rides are either very flat or pretty steep... 10-15% grades where you are (or at least I am) on the brakes a little bit the whole way down.




Then you don't want carbon clinchers. If you are on the brakes for an entire descent you will kill them. 

The failure mode is that the epoxy softens. The tire is pushing the rim walls apart with 100+ psi. One part of the rim spreads out a little. That part now gets more brake heat because the brakes are tighter on it, so it spreads more. Then the tire bead pops over the rim, the tube sticks out and explodes. I have seen this under 150 lb skilled descenders who braked too much on a steep descent.


Brake heat depends on a lot of factors. Rider weight, confidence on descents, and the length and steepness of descents. But what's more important than all of those is how technical the descents are.

A descent with many tight turns right after each other puts much more heat into the brakes than a steeper but straight descent. There's a couple reasons- first, the faster you go the more potential energy is consumed by air resistance, which does not heat the brakes. Second, the faster you go the more the rims are cooled by air convection.
I regularly used carbon clinchers with poor heat qualities in the biggest climbing race in north america, the Everest Challenge. Even with 29,035 feet of climbing in two days and the same amount of descending, little of the descending was technical. The vast majority was tucked as aero as you can get, don't touch the brakes. Even the crappiest carbon clincher rims can handle slowing from 55 to 20 mph once. It's slowing from 35 to 15 over and over with little time off the brakes that will kill them.


So the first consideration is how technical are the descents you're going to be doing. Then the other factors come in to play.

But unless you're racing they're not worth the hassle and expense. The speed improvement is only noticeable on descents and even then it's small.


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## bmach (Apr 13, 2011)

You might not be worried about spokes but in my opinion I think you should be. Think about it, how much weight do 4 spokes add?


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## tvad (Aug 31, 2003)

Will your tubes blow due to heat build up? Probably not. But, it has been reported over the years. Can _anyone_ offer you assurances that neither the Zipp 404 or Enve SES 6.7 will overheat and blow out? 

I'll wager no one from Zipp or Enve would officially say, "no". The company lawyers won't allow it; too much risk of liability and resulting legal action. 

There's no guarantee on a hot day if you're constantly riding the brakes down a several mile descent that a tube won't blow causing the tire to come off the rim sending you into a catastrophic crash. 

Riding the brakes on a descent is poor technique, which suggests some improvement in your descending skills is in order.

Consider this...if you're constantly worried about a tire blowing out on a descent, how will you focus on the task of descending...and how enjoyable will that descent be for you?

Don't know what to tell you other than buy what you want.


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## thisisthebeave (Aug 30, 2015)

tvad said:


> Will your tubes blow due to heat build up? Probably not. But, it has been reported over the years.
> 
> There's no guarantee on a hot day if you're constantly riding the brakes down a several mile descent that your tubes won't blow causing your tire to come off the rim sending you into a catastrophic crash.
> 
> ...


If it matters, I don't ride on hot days. The hottest I'll ride in is about 80 degrees. I ride in the mornings or not at all during summer.

Also, if its a technique issue, I can brake hard for ~3 seconds, let off, brake hard for ~3 seconds, etc, as opposed to lightly holding non stop?



bmach said:


> You might not be worried about spokes but in my opinion I think you should be. Think about it, how much weight do 4 spokes add?


I'm looking at off-the-shelf builds so sometimes it just isn't an option to get a higher spoke count. I don't want to turn down an otherwise perfect wheel because it has 4 fewer spokes because in my experience the rim matters more than spoke count.

I'm not looking at lightweight aluminum rims here. ENVE has no rider weight limit for a reason, the rims are beefy. The pros, who put down a lot more power than you or I, regardless of my weight, are fine on these wheels. If Cavendish can put down 1,800 watts in an extended sprint and be fine, I should be fine since I know I peak around 1,500 watts for a couple seconds.


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## tvad (Aug 31, 2003)

thisisthebeave said:


> If it matters, I don't ride on hot days. The hottest I'll ride in is about 80 degrees. I ride in the mornings or not at all during summer.
> 
> Also, if its a technique issue, I can brake hard for ~3 seconds, let off, brake hard for ~3 seconds, etc, as opposed to lightly holding non stop?


Cool morning rides reduce risk. Although, I don't understand the point of eliminating on hot days. Isn't the point to ride whenever one wants? There's no magic in carbon rims that you can't also find in aluminum rims, which will not curtail any of your riding.

On and off braking technique is far better than constant pressure on the rim, no matter how light.

Same answer from me, though...no guarantees...buy what you want.

This is one of those perplexing threads in which a question is asked, yet clearly the outcome is decided before even one response is given.


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## thisisthebeave (Aug 30, 2015)

tvad said:


> Cool morning rides reduce risk.
> 
> On and off braking technique is far better than constant pressure on the rim, no matter how light.
> 
> Same answer from me, though...no guarantees...buy what you want.


There's a loop I do that has one descent that's pretty twisty (see pic) and steep at times, but it's only a ~800ft descent.



View attachment 309503


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## ericm979 (Jun 26, 2005)

thisisthebeave said:


> Also, if its a technique issue, I can brake hard for ~3 seconds, let off, brake hard for ~3 seconds, etc, as opposed to lightly holding non stop?


That's a little better. But not good enough for safety on carbon clinchers. You should be braking only for corners (and stop signs, etc).


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## thisisthebeave (Aug 30, 2015)

ericm979 said:


> That's a little better. But not good enough for safety on carbon clinchers. You should be braking only for corners (and stop signs, etc).


Can't say I agree with that... if something runs out into the road or there's debris in the road you can't see right away, I'd rather be going 35-40 than 50. I'm not enough of an adrenaline junky to feel safe going 50... adjust the numbers as you see fit but I just don't like going THAT fast on the road with cars.


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## TmB123 (Feb 8, 2013)

Don't Zipp have a 220 pound weight limit on their carbon wheels? - (not sure if this is a hard limit or advised) *edit* - actually that is incorrect, the 404's are listed at 250lbs limit.

btw - technically Zipps aren't full carbon clinchers (although we still call them that), they still have an aluminum hoop inside of them


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## ericm979 (Jun 26, 2005)

If you can't descend without riding the brakes you risk carbon clincher failure.

There are descents where I live that I won't do on carbon clinchers. I've been riding motorcycles for 40 years, I'm a very confident descender and I weigh 145 lbs. The descents in question are steep and technical. I've had a tire blow off a carbon rim from heat. 

What I'm saying here is not that you suck, it's that carbon clinchers can't handle lots of braking. If you do lots of braking for whatever reason you should not use them.


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## ericm979 (Jun 26, 2005)

TmB123 said:


> btw - technically Zipps aren't full carbon clinchers (although we still call them that), they still have an aluminum hoop inside of them


You're thinking of the old zipps. Modern zipps are full carbon.


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## tvad (Aug 31, 2003)

TmB123 said:


> btw - technically Zipps aren't full carbon clinchers (although we still call them that), they still have an aluminum hoop inside of them


The old 404 were combo aluminum/carbon, but I don't believe that applies to the 404 Firecrest or Firestrike rims. Can you provide a link that shows the construction of the 404 Firecrest or Firestrike includes aluminum?


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## TmB123 (Feb 8, 2013)

tvad said:


> The old 404 were combo aluminum/carbon, but I don't believe that applies to the 404 Firecrest or Firestrike rims. Can you provide a link that shows the construction of the 404 Firecrest or Firestrike includes aluminum?


I thought they were full carbon as well (i have a set of 202FC and Firestrikes) but read somewhere the other day about the aluminium hoop and when I just googled the rider weight limit came across these Zipp FAQ's Zipp - Speed Weaponry | Support | FAQs (about the 6th dot point down) but looking at them now think they may be an old set of FAQ's because clicking back to support and then FAQ's again it isnt there. So happy to be wrong on that as was a little disappointed to read it.


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## tvad (Aug 31, 2003)

^You're looking at an old webpage. If you look under the weight limit FAQ, you'll see references to ZED6, ZED8 and ZED10 wheels...all discontinued.

The current Zipp carbon rims are 100% carbon.


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## TmB123 (Feb 8, 2013)

Yeah, I edited the weight limit above in my original post


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## izza (Jul 25, 2012)

The latest Giant carbon clinchers have a higher temperature rating than Zipps and have a 130kg rider weight limit.


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## thisisthebeave (Aug 30, 2015)

izza said:


> The latest Giant carbon clinchers have a higher temperature rating than Zipps and have a 130kg rider weight limit.


Where can you find published temp ratings? I'd prefer to go with Enve or Zipp, if for nothing other than an easier resale whenever I get new wheels and sell these.


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## deviousalex (Aug 18, 2010)

thisisthebeave said:


> I'm not looking at lightweight aluminum rims here. ENVE has no rider weight limit for a reason, the rims are beefy. The pros, who put down a lot more power than you or I, regardless of my weight, are fine on these wheels. If Cavendish can put down 1,800 watts in an extended sprint and be fine, I should be fine since I know I peak around 1,500 watts for a couple seconds.


That's not relevant to your situation. It's not when you are putting out 1500 watts the damage happens, it's when you hit a pot hole at 40 mph is the problem. Cavendish weighs nearly 100lbs less than you.


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## tvad (Aug 31, 2003)

deviousalex said:


> ...it's when you hit a pot hole at 40 mph is the problem.


Ouch. That's gonna leave a mark regardless of wheel material!


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## mikerp (Jul 24, 2011)

thisisthebeave said:


> Where can you find published temp ratings? I'd prefer to go with Enve or Zipp, if for nothing other than an easier resale whenever I get new wheels and sell these.


Let's back up a bit.
Why do you want Carbon Clinchers, if it's just for aesthetics that is fine.
Based on your riding style and concerns (braking/reselling), I wouldn't recommend them for you at this point.


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## Diopena1 (Jul 21, 2011)

I'm 5'11'', about 210 lbs right now.... ride carbon clinchers, BUT (emphasis on but), do not ride the brakes on a downhill... Even on a flat, in 105 degree weather at 15 mph, coming to a stop for a red light warms the rims up quite a bit. I'm not even concerned about rim warpage, or tire bead failure, BUT I am aware that it has, and could happen to anyone.
As stated you have a few things working against selecting a carbon clincher safely.
1) tire pressure, and weakening epoxy due to excessive heat <- only compounded more by rider weight, and current speed. Remember when they mentioned friction and heat are directly related to one another?..... Add some momentum, and leverage from weight, and that number multiplies by a bit....
2) Brake pad selection... This is important, because some pads will dissipate (or cool off) better than others... still this isn't a loophole for the points stated in #1.
Bottom line is buy what you want, Personally, I'd prefer if the facts were more evident, as some of the "stated by manufacturer" hoopla is just there both for legal reasons, and can be misconstrued. 
If I may suggest, see a wheel builder (Ergott comes to mind), and see what they suggest based on your physical characteristics, riding style, and your needs before putting all your cards down on the table....


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## thisisthebeave (Aug 30, 2015)

deviousalex said:


> That's not relevant to your situation. It's not when you are putting out 1500 watts the damage happens, it's when you hit a pot hole at 40 mph is the problem. Cavendish weighs nearly 100lbs less than you.


Our roads are pretty great out here. Can't remember the last time I hit a pothole. Anyway, can we just operate under the assumption that 20 vs 24 or 24 vs 28 or whatever you want to pick isn't relevant? My personal experience has shown led me to not be concerned with it and nothing you can say with convince me otherwise.

ENVE rims only come in 16, 20, and 24 holes anyway, so saying that I need 28 or 32 isn't relevant since it isn't possible anyway. ENVE wouldn't cap at 24 holes and offer a 5 year warranty with no weight limit if it wouldn't work.

I'm solely concerned with tube blowouts when descending.


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## thisisthebeave (Aug 30, 2015)

mikerp said:


> Let's back up a bit.
> Why do you want Carbon Clinchers, if it's just for aesthetics that is fine.
> Based on your riding style and concerns (braking/reselling), I wouldn't recommend them for you at this point.


Combo of weight and aero and comfort with looks as a DISTANT 4th. With full carbon, you get the weight of a shallow-mid depth alloy or carbon/alloy hybrid (like the DA C35) but in a profile. With the hybrid rims or the alloy rims, you have to pick weight or aero.


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## deviousalex (Aug 18, 2010)

thisisthebeave said:


> Anyway, can we just operate under the assumption that 20 vs 24 or 24 vs 28 or whatever you want to pick isn't relevant? My personal experience has shown led me to not be concerned with it and nothing you can say with convince me otherwise.


You can operate under that assumption. The rest of us live in the real world where we know spoke count is important for stiffness and durability.

Road to Roubaix, Part 1 | SILCA



> The initial testing was conducted with about a dozen wheels including ptototype Roubaix wheels, vintage Mavic Roubaix aluminum box section wheels, and the 2007 race favorite 32 spoke Ambrosio Crono box section rimmed wheels. After the first full day of testing, crafting new anvil geometries, re-thinking the fixtures, re-thinking everything we could be doing wrong, we realized that we weren’t doing anything wrong at at all: The box section wheels were in fact, radially stiffer than most of the deeper carbon wheels!


Granted, that's 8 years ago but yes, spokes do matter.

You also stated that weight is important. Sorry to burst your bubble, but saving 300 grams at 235 lbs isn't going to do squat. Aero is important, but if you are on a positive rise stem I'll just sit back and laugh . Some coworkers ask me about aero wheels then I look at their bike position and tell them to stretch and ride in a more aggressive position. But hey, if you want to spend money go for it. I really don't care.


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## robt57 (Jul 23, 2011)

deviousalex said:


> You can operate under that assumption. The rest of us live in the real world where we know spoke count is important for stiffness and durability.



I am betting more folks live in the non real world as it pertains to this. ;O


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## thisisthebeave (Aug 30, 2015)

deviousalex said:


> You can operate under that assumption. The rest of us live in the real world where we know spoke count is important for stiffness and durability.
> 
> Road to Roubaix, Part 1 | SILCA
> 
> ...


Do you want to just pick the one part of my post that is subjective and discredit the whole thing?

ENVE doesn't make rims with more than 24 holes, plain and simple. What would you like me to do about it? You're comparing cheap shallow aluminum wheels to top of the line deep carbon wheels. Of course a lightweight aluminum wheel needs more spokes than a deep stiff carbon rim! Do you think that maybe, just possibly, ENVE knows what they're doing when they chose 24 spokes?

edit: I didn't say spokes don't matter, I said I'm not concerned with it. Firstly because with ENVE I don't have a choice, but secondly, rim matters more and I'm getting along fine with 16f/21r so why wouldn't 20f/24r work?


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## mikerp (Jul 24, 2011)

thisisthebeave said:


> Combo of weight and aero and comfort with looks as a DISTANT 4th. With full carbon, you get the weight of a shallow-mid depth alloy or carbon/alloy hybrid (like the DA C35) but in a profile. With the hybrid rims or the alloy rims, you have to pick weight or aero.


What is your average moving speed on the flats? (aero only comes into play if you are moving at the right speeds).


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## thisisthebeave (Aug 30, 2015)

mikerp said:


> What is your average moving speed on the flats? (aero only comes into play if you are moving at the right speeds).


Moderate pace riding solo in the hoods? 22-23. Riding hard in the hoods 23-24. Riding HARD 24-28.

I'm genuinely only curious about blowouts when braking, not spoke counts or whether it's "worth it" for me.


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## deviousalex (Aug 18, 2010)

thisisthebeave said:


> Do you want to just pick the one part of my post that is subjective and discredit the whole thing?


I didn't discredit your whole post. I just said you live in a fantasy world when it comes to spoke count.



> ENVE doesn't make rims with more than 24 holes, plain and simple. What would you like me to do about it?


Not buy ENVE perhaps? Your decision really.



> Do you think that maybe, just possibly, ENVE knows what they're doing when they chose 24 spokes?


Do you think that maybe, just possible, ENVE wasn't looking at 200+lbs people as their target market when they created the wheels?

And to answer your original question, no I wouldn't trust carbon clinchers. I weigh 140lbs and am a fairly capable descender. One some of the steeper grades around here I had a pair of Reynolds wheels (with their CTg braking surface) howling like mad on certain descents. I ended up returning the wheels. I now ride around on 24/28 spoked HED Belgium like rims.

But hey, but whatever makes you happy. You're only lowering the price for other people in the future. So go for it!


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## tvad (Aug 31, 2003)

You guys are screaming into a hurricane.

thisisthebeave is going to buy ENVE or Zipp wheels as soon as his concern about braking and tube blowout is sufficiently addressed.


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## Jwiffle (Mar 18, 2005)

Get a disc brake equipped bike. Carbon clincher heat buildup and tube blowout problem solved!


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## tvad (Aug 31, 2003)

Jwiffle said:


> Get a disc brake equipped bike. Carbon clincher heat buildup and tube blowout problem solved!


Good suggestion!


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## TmB123 (Feb 8, 2013)

OP - if you arent going to listen to the advice of the others you might as well toss a coin and pick which one you like the best. I doubt you will have any problems with either the Zipps or Enves with regards to tube blowouts.

fwiw - I weigh 85kg and sounds like ride similar descents to you. I rarely use the brakes but do hammer both my 202's and 404's pretty hard into hair pins and T junctions on 15% descents stopping from around 80-90kph. They squeal but have never had any problems or concerns with overheating in the Australian summer.


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## thisisthebeave (Aug 30, 2015)

deviousalex said:


> I didn't discredit your whole post. I just said you live in a fantasy world when it comes to spoke count.
> 
> 
> 
> ...


They wouldn't go out of their way to say there isn't a rider weight limit AND offer the longest warranty in the business.


Would you suggest a different brand? Zipp/Enve/Roval all use 18-24 spokes. I'd rather not get some off-brand rim just to get 28-32 spokes. With a stiff/beefy carbon rim, it simply isn't necessary. Did you miss that I'm currently on a 16f/21r setup and it doesn't leave any stiffness to be desired? Or that I'm on a 24f/28r (with weenie DT Rev spokes at that) setup on my mountain bike?


A shallow aluminum rim like a HED Belgium NEEDS more spokes than a deep carbon one does.


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## thisisthebeave (Aug 30, 2015)

TmB123 said:


> OP - if you arent going to listen to the advice of the others you might as well toss a coin and pick which one you like the best. I doubt you will have any problems with either the Zipps or Enves with regards to tube blowouts.
> 
> fwiw - I weigh 85kg and sounds like ride similar descents to you. I rarely use the brakes but do hammer both my 202's and 404's pretty hard into hair pins and T junctions on 15% descents stopping from around 80-90kph. They squeal but have never had any problems or concerns with overheating in the Australian summer.


I'm not disregarding advice, I'm simply pointing out that I'm not concerned with spoke counts. My experience says the rim matters a lot more. How else would I be on a 16f/21r setup right now? That's one of the lowest counts in the industry. ENVE couldn't profitably offer "no rider weight limit" AND a 5 year warranty if 20f/24r spokes was a problem. And they aren't just silent about the weight limit, they go out of their way to say "Hey look, NO WEIGHT LIMIT".

You all are giving advice I didn't ask for. I'm asking about tire blowouts NOT spoke counts and said that from the beginning.


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## deviousalex (Aug 18, 2010)

thisisthebeave said:


> ENVE couldn't profitably offer "no rider weight limit" AND a 5 year warranty if 20f/24r spokes was a problem. And they aren't just silent about the weight limit, they go out of their way to say "Hey look, NO WEIGHT LIMIT".


Nothing in ENVE's warranty says they have to true your wheels either. Sometimes companies don't have a rider weight limit because if something happens with a rider that's under the stated weight limit they open themselves up to a lawsuit.

Also, I think we've addressed your question about the blowouts. Whatever we say, mileage on it may vary. It really depends on the descent itself as well as your braking technique. One thing I forgot to mention is that when I had my Reynolds the brakes would get noticeably spongey when they heat up. Modulation and braking power would decrease.

One thing I've realized as I've become more experienced is that trusting your equipment is paramount and trumps light weight, aero, etc. If you're second guessing your equipment into a corner, you're not going to go through that corner as fast as you would otherwise.

But hey, buy whatever makes you happy. I think this forum has given you a lot of advice, you can take it or leave it.


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## tvad (Aug 31, 2003)

thisisthebeave said:


> ENVE couldn't profitably offer "no rider weight limit" AND a 5 year warranty if 20f/24r spokes was a problem.


Read the ENVE warranty carefully. It specifically does not cover:


> Warranty does not apply to parts manufactured by other manufacturer (ex. hubs, spokes, nipples). Consult the individual manufactures for issues related to these parts.


The only part of ENVE wheels that's warrantied are the rims.


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## thisisthebeave (Aug 30, 2015)

deviousalex said:


> Nothing in ENVE's warranty says they have to true your wheels either. Sometimes companies don't have a rider weight limit because if something happens with a rider that's under the stated weight limit they open themselves up to a lawsuit.
> 
> Also, I think we've addressed your question about the blowouts. Whatever we say, mileage on it may vary. It really depends on the descent itself as well as your braking technique. One thing I forgot to mention is that when I had my Reynolds the brakes would get noticeably spongey when they heat up. Modulation and braking power would decrease.
> 
> ...


Yeah I've read a few people who say they weren't happy with Reynolds braking or stiffness. They're not on my short list 


tvad said:


> Read the ENVE warranty carefully. It specifically does not cover:
> The only part of ENVE wheels that's warrantied are the rims.


I realize that spokes aren't covered by the warranty, but if spokes (count or type) were insufficient in supporting the rim, they wouldn't spec them.

Am I the only one who thinks that a stiff/deep carbon rim should be able to handle having fewer spokes then a shallow aluminum one? If aluminum setups are often 24/28, why is it unreasonable to use 20/24 on carbon? Hell, my stock aluminum wheels were 18/24 and those were fine too. If aluminum with 18/24 is fine with me, why wouldn't carbon (from a reputable manufacturer) with 20/24 be fine?


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## tvad (Aug 31, 2003)

I wasn't implying anything about spoke count; simply pointing out what the ENVE warranty covers. Some folks believe the ENVE 5 year warranty covers the full wheels, which as you know isn't the case.


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## dcgriz (Feb 13, 2011)

thisisthebeave said:


> Am I the only one who thinks that a stiff/deep carbon rim should be able to handle having fewer spokes then a shallow aluminum one? If aluminum setups are often 24/28, why is it unreasonable to use 20/24 on carbon? Hell, my stock aluminum wheels were 18/24 and those were fine too. If aluminum with 18/24 is fine with me, why wouldn't carbon (from a reputable manufacturer) with 20/24 be fine?


It may be but you need to compare carbon to carbon rather than carbon to aluminum for a more accurate deduction. The bottom half of an aluminum rim wheel bows out in conformance to the road and the rider's pedaling. Carbon rim wheels don't do that; they tend to want to move laterally under one plane so spokes (more of them) are needed to keep an overly stiff rim from rubbing the brake pads. It's a balancing act trying to optimize the rim stiffness vs. spoke stiffness without a one-fits-all solution also due to unique rider imposed variables such as weight and laterally applied load (sprinting while tilting the bike, etc.). Kopecky wrote an excellent article on this here Debunking Wheel Stiffness - Slowtwitch.com

Now regarding your tire blow-out question; I'm not clear on what kind of conformation or assurance you seek. Tubes have blown-out of carbon clinchers due to the overheating from the sustained application of brakes. The degree of this happening is affected by many variables such as the type of descent, your speed, your weight, your rider skills, ... just to name a few. Very hard, if not impossible, to predict whether or when this may happen to you.

I do have a set of Enve 45's (28 spokes on the rear ) and never had an issue of a tube blow-out due to overheating BUT I don't take them when I know the descending to be sustained AND technical OR expect rain. For these times aluminum wheels are put on any bike I'm taking with me. Overheating under normal riding on rolling terrain has never been an issue with me. For whatever it's worth, I am well into Clyde territory, both vertically and on the scale.

Hope it helps.


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## mikerp (Jul 24, 2011)

thisisthebeave said:


> I'm not disregarding advice, I'm simply pointing out that I'm not concerned with spoke counts. My experience says the rim matters a lot more. How else would I be on a 16f/21r setup right now?


As you have this wealth of knowledge/experience why are you asking for suggestions?
Buy the wheels you want, go ride them, and make history.


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## ibericb (Oct 28, 2014)

Two issues have been raised - spoke count and heat. The OP has dismissed the concerns expressed about spoke count based on his experience, and the fact that Enve offers the product with a five year warranty without a rider weight limit. A couple of thoughts:

Spoke count is surely adequate for well maintained wheels used in normal riding conditions. The issue with lower spoke count wheels is the room for error when things get a bit out of whack, or when you depart from normal riding conditions (e.g., hit that unexpected pothole, ride over a curb, etc.). When that happens, and there are fewer spokes, the situation can go from what would have been tolerable with a higher spoke count to catastrophic quickly. When that happens a warranty against defects in workmanship or materials is meaningless. As long as you don't depart from normal riding conditions, and maintain your wheels well, the spoke count shouldn't be an issue. Consider higher spoke counts like an insurance policy against catastrophic loss - you really hope and intend that you will never need it, but you pay for it because the cost if there is that unexpected problem would be intolerable.

The issue with heat is again when you depart from normal riding conditions. Normal riding conditions means that you don't overheat your wheels from braking. The warranty doesn't mean anything when you experience excessive heating of the rim due to what would then be viewed as "excessive" braking. Enve builds a great product that meets some demanding standards. But they can't control anyones use or misuse of their products. Braking hard enough to cause overheating that leads to composite degradation would simply indicate misuse or abuse. Warranties only cover defects in workmanship and materials. They don't cover overheating a rim due to what would be considered "excessive" braking as evidenced by heat-induced a failure. 

Carbon composite wheels pose risks for failures that don't exist with alloy wheels, and it's more than just loosing tire bead-to-rim integrity. It's clear that you (the OP) appreciate those risks. Only you can decide if you are willing to accept them. Most who have replied to you, based on their knowledge and experience using carbon wheels, would not.


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## thisisthebeave (Aug 30, 2015)

dcgriz said:


> It may be but you need to compare carbon to carbon rather than carbon to aluminum for a more accurate deduction. The bottom half of an aluminum rim wheel bows out in conformance to the road and the rider's pedaling. Carbon rim wheels don't do that; they tend to want to move laterally under one plane so spokes (more of them) are needed to keep an overly stiff rim from rubbing the brake pads. It's a balancing act trying to optimize the rim stiffness vs. spoke stiffness without a one-fits-all solution also due to unique rider imposed variables such as weight and laterally applied load (sprinting while tilting the bike, etc.). Kopecky wrote an excellent article on this here Debunking Wheel Stiffness - Slowtwitch.com
> 
> Now regarding your tire blow-out question; I'm not clear on what kind of conformation or assurance you seek. Tubes have blown-out of carbon clinchers due to the overheating from the sustained application of brakes. The degree of this happening is affected by many variables such as the type of descent, your speed, your weight, your rider skills, ... just to name a few. Very hard, if not impossible, to predict whether or when this may happen to you.
> 
> ...


Thanks, that is helpful.

Another option is to run my stock wheels on hilly days but I feel like that defeats the purpose of having a nice wheel if you can't ride it under most circumstances.

Rain, definitely agreed. My cross bike has a second set of wheels with Gatorskins (and disc brakes) for rainy days.


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## thisisthebeave (Aug 30, 2015)

mikerp said:


> As you have this wealth of knowledge/experience why are you asking for suggestions?
> Buy the wheels you want, go ride them, and make history.


Let's go full circle, shall we? From the beginning I said I wanted feedback about blowouts, not spokes. My experience says that spoke count is less important than the rim. However, I have no experience with full carbon clinchers.

Of all the wheels in my house, they are:

16f/21r - shimano bladed spokes (a little bigger than CX Rays), hybrid rim
18f/24r - DT comp spokes (2.0-1.8-2.0), alu rim
24f/28r - DT rev spokes (2.0-1.5-2.0), carbon rim
21f/24r - DT champ spokes (2.0 straight gauge), alu rim
20f/24r - CX Rays, alu rim
28f/32r - DT comp spokes (2.0-1.8-2.0), carbon rim

Besides the bottom one they are all low spoke count. I've broken one spoke ever and it was after a stick got caught in my derailleur and my derailleur went into my spokes, gouging the spokes. After detangling everything, the spoke broke a few miles later. Other than that, no spokes breaking, brake rub, etc.

You're just regurgitating "I read on the internet that heavier riders need...." at this point or you're trolling.


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## thisisthebeave (Aug 30, 2015)

ibericb said:


> Two issues have been raised - spoke count and heat. The OP has dismissed the concerns expressed about spoke count based on his experience, and the fact that Enve offers the product with a five year warranty without a rider weight limit. A couple of thoughts:
> 
> Spoke count is surely adequate for well maintained wheels used in normal riding conditions. The issue with lower spoke count wheels is the room for error when things get a bit out of whack, or when you depart from normal riding conditions (e.g., hit that unexpected pothole, ride over a curb, etc.). When that happens, and there are fewer spokes, the situation can go from what would have been tolerable with a higher spoke count to catastrophic quickly. When that happens a warranty against defects in workmanship or materials is meaningless. As long as you don't depart from normal riding conditions, and maintain your wheels well, the spoke count shouldn't be an issue. Consider higher spoke counts like an insurance policy against catastrophic loss - you really hope and intend that you will never need it, but you pay for it because the cost if there is that unexpected problem would be intolerable.
> 
> ...


I'm really just not concerned with spoke count. The roads around here are good so I don't have to worry about potholes. It's never cold here and I only ride in the morning during summer. I don't hop curbs on a road bike, I don't commute on poor roads, I don't hit pot holes, there is never debris in the road (besides glass/gravel).

I guarantee you that 20f/24r spokes will suffice for me. I have a half dozen wheelsets in this house and 4 of them have about that many or fewer spokes. I have wheelsets with high counts and low counts and there is no tangible difference between them for where and how I ride.

I am ONLY concerned about blowouts from heat. Only. If it's a real concern, and it sounds like it might be, I'll keep what I have. I'm not trying to convince anyone that I need or should have full carbon wheels, I'm just asking if they'll be fine. I don't NEED them but *IF* they work for me, I'll buy them.


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## tvad (Aug 31, 2003)

thisisthebeave said:


> I am ONLY concerned about blowouts from heat. Only. If it's a real concern, and it sounds like it might be, I'll keep what I have.


What exactly do you need to read that will put this to rest?



ibericb said:


> The issue with heat is again when you depart from normal riding conditions. Normal riding conditions means that you don't overheat your wheels from braking. The warranty doesn't mean anything when you experience excessive heating of the rim due to what would then be viewed as "excessive" braking. Enve builds a great product that meets some demanding standards. But they can't control anyones use or misuse of their products. *Braking hard enough to cause overheating that leads to composite degradation would simply indicate misuse or abuse. Warranties only cover defects in workmanship and materials. They don't cover overheating a rim due to what would be considered "excessive" braking as evidenced by heat-induced a failure.*


An excellent point.


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## ibericb (Oct 28, 2014)

thisisthebeave said:


> I'm really just not concerned with spoke count.


You've made that abundantly clear, and it has been well understood. The only reason I raised it at all was to put higher spoke count into context. Using the insurance analogy, you've decided the risk for you is sufficiently low that you choose not to carry the "insurance" protection that a higher spoke count would provide. Perfect.



> ... I am ONLY concerned about blowouts from heat. Only. If it's *a real concern*, and it sounds like it might be, I'll keep what I have. ... .


As has been expressed by several, it is a real and legitimate concern. That doesn't mean it will be a problem for you, just that it could be and has been for others. That leads to the real concern. There is no way to know _a priori_ if it will be a real problem for you. It's a risk - take it if you wish.


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## thisisthebeave (Aug 30, 2015)

tvad said:


> What exactly do you need to read that will put this to rest?


How about more than 1-2 heavy riders responding to blowouts on descents (the topic) rather than a bunch of skinny riders talking about spoke counts (not the topic)?


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## thisisthebeave (Aug 30, 2015)

ibericb said:


> You've made that abundantly clear, and it has been well understood. The only reason I raised it at all was to put higher spoke count into context. Using the insurance analogy, you've decided the risk for you is sufficiently low that you choose not to carry the "insurance" protection that a higher spoke count would provide. Perfect.
> 
> 
> 
> As has been expressed by several, it is a real and legitimate concern. That doesn't mean it will be a problem for you, just that it could be and has been for others. That leads to the real concern. There is no way to know _a priori_ if it will be a real problem for you. It's a risk - take it if you wish.


I'm just shocked it took 50 replies to get past the fact that 20f/24r or fewer on an alu rim works fine for me, why wouldn't it work on a carbon rim?

Anyway, is the heat buildup a real concern with tubulars?


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## tvad (Aug 31, 2003)

thisisthebeave said:


> How about more than 1-2 heavy riders responding to blowouts on descents (the topic) rather than a bunch of skinny riders talking about spoke counts (not the topic)?


My question was genuine.

Let's face it, with a title "Any heavier riders on full carbon clinchers", and considering you mentioned your weight in the first post, it stands to reason comments are going to include spoke count since spoke count typically relates directly to rider weight, whereas rim heating due to braking has more to do with rider descending technique and less to do with rider weight. 

If you ask a question on an internet forum, you can expect to receive replies that go beyond the scope of the question. It's just the way it is, and from a practical standpoint there's little one can do to police it. You'll find your experience more pleasant if you can accept this reality, and accept the well intentioned if unsolicited comments.


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## dcgriz (Feb 13, 2011)

thisisthebeave said:


> Another option is to run my stock wheels on hilly days but I feel like that defeats the purpose of having a nice wheel if you can't ride it under most circumstances.


If I was to have an one wheel quiver then carbon definitely would not be it because as you said it has limitations and associated risks under certain conditions. If technical descents is what you refer to as "most circumstances" then the risks outweigh the benefits and carbon rims would not be justified for me. On rolling terrain I would not be concerned with heat buildup from braking as it has never been an issue to me.


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## deviousalex (Aug 18, 2010)

Buy me a food budget for the year and some ENVE wheels and I'll get back to you about blowouts. Deal?

But on a serious note, you're hoping that heavier riders will come out of the woodwork 50+ posts later with relevant experience. If tehy haven't chimed in by now, I don't think it's going to happen.


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## ibericb (Oct 28, 2014)

thisisthebeave said:


> Anyway, is the heat buildup a real concern with tubulars?


The answer is absolutely. It was a big issue in the Tour of Oman earlier this year. See this article from Lenard Zinn. You can see it as it happened in this GCN video, from about 40 sec's in.






While Oman was exceptionally hot, the basic issue is heat transfer from a carbon rim. A carbon rim once heated, by whatever mechanism (ambient air temp or prolonged or excessive braking), doesn't transfer or loose the heat as readily as an alloy rim. That can lead to excessive heating of the rim with ensuing tire blowouts, or structural damage to the rim. So it can happen to the best of riders on a really hot day, or it can happen to less skilled riders who brake heavily or persistently under substantial loads without the heating provided by the ambient temps of Oman.

Beyond immediate tire failures, the big issue with heat buildup is composite matrix degradation due to overheating. That is typically localized to where the excessive heating occurred. That can lead to problems like delamination of the composite, and loss of rim structural integrity. That kind of structural damage may precede a tire blow-off. While that's been a problem on some wheels in the past it takes a lot of heat, and in updated composites (last 2-3 years) it is apparently less of a problem.


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## thisisthebeave (Aug 30, 2015)

dcgriz said:


> If I was to have an one wheel quiver then carbon definitely would not be it because as you said it has limitations and associated risks under certain conditions. If technical descents is what you refer to as "most circumstances" then the risks outweigh the benefits and carbon rims would not be justified for me. On rolling terrain I would not be concerned with heat buildup from braking as it has never been an issue to me.


"Most circumstances" for me is flat terrain, I live about 30 miles from the foothills and I prefer to ride out my front door. But if I drive a little bit, I can see some serious hills. But if one steep descent with a few turns is going to blow up my tubes, then I'll keep what I have.


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## ibericb (Oct 28, 2014)

Just something to add into your analysis. Part of the "solution" for the heating with braking on carbon rims has been in brake pads. Enve, for example, specifically requires you to use their brake pads or the wheel warranty is void. Those pads for carbon wheels will typically have a lower coefficient of friction. That has two effects: (1) less heat generated for a given brake effort and duration , and (2) increased slowing and stopping distances. The point is if you go with carbon rims you should expect reduced braking capabilities.


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## ACree (Feb 5, 2006)

Jwiffle said:


> Get a disc brake equipped bike. Carbon clincher heat buildup and tube blowout problem solved!


This ^. The best solution to carbon braking.

FWIW, as a clydesdale myself, I have blown tires off of aluminum rims when the descent was long and steep enough. I now have discs (and also, November Rail 52s).


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## thisisthebeave (Aug 30, 2015)

ibericb said:


> Just something to add into your analysis. Part of the "solution" for the heating with braking on carbon rims has been in brake pads. Enve, for example, specifically requires you to use their brake pads or the wheel warranty is void. Those pads for carbon wheels will typically have a lower coefficient of friction. That has two effects: (1) less heat generated for a given brake effort and duration , and (2) increased slowing and stopping distances. The point is if you go with carbon rims you should expect reduced braking capabilities.


My current setup almost has too much braking power so I could accept a little less braking. I get what you're saying though.


ACree said:


> This ^. The best solution to carbon braking.
> 
> FWIW, as a clydesdale myself, I have blown tires off of aluminum rims when the descent was long and steep enough. I now have discs (and also, November Rail 52s).


Find me an aero road bike with discs and a stack height of at least 640 and I'm in. Current bike has a stack of 654 and I could handle a little less but not too much.


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## tvad (Aug 31, 2003)

If you want rim brakes with superior modulation look at eebrakes.

I do believe the best solution to your rim overheating and tube blow-out concerns are disc brakes.


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