# carbon clincher rims to tublar - conversion



## senji (Aug 14, 2012)

*carbon clincher rims to tubular - conversion*

Hi everyone! Maybe the topic is kind of weird but the case is kind interesting. My friend had a pair o carbon clincher wheels but unfortunetly he didn`t mind the correct pressure which was about 8 bar. It resulted in sidewall crack near breaking surface. I decided to buy it for him and repair. Of course later usege with clincher tires was impossible so I did little conversion. I grinded "clincher mounts" which are located on inner sidewalls. Then I applied few leyers of carbon fiber and epoxy resin the repair the broken surface and leave it for few days. The last step was tubular tire mount which I did without any problems.

https://s8.postimage.org/rcqt7l9sl/bez_tytu_u.jpg

Tubular is glued very firm. I tried hard to break it off from the rim with bare hands but it fit very tight. What do you think about it? will it be safe?


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## slowdave (Nov 29, 2005)

How much are you teeth worth?
It may be safe but where is the brake track now? 
I dont think i could ride the rim and not be constantly worrying about it failing


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## senji (Aug 14, 2012)

Brake track hasn`t been changed. I only grinded a bit of the inner side to enlarge surface area for better adhesion of tubular.


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## steelbikerider (Feb 7, 2005)

Back in the day, I put a used tubular on a clincher rim a couple of times to get home. An old tire with glue would stay on a clincher rim as long as you didn't do any crit corners.


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## Kontact (Apr 1, 2011)

It doesn't sound like you did anything to keep the brake track from eventually cracking out, possibly wedging itself into the brake and causing an awful crash.

I wouldn't even ride near you on those things.


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## senji (Aug 14, 2012)

Like I said at the begining.... Rim was repaired with few layers of carbon fiber and epoxy resin so thats not the point. The only thing I`m awere of is tubular tire mount. Clincher rim is little deeper (about 5-6 mm) than tubular rim (3-4 mm). So I worry the most is that tubular will come of the rim on very tight corner;/


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## Kontact (Apr 1, 2011)

senji said:


> Like I said at the begining.... Rim was repaired with few layers of carbon fiber and epoxy resin so thats not the point. The only thing I`m awere of is tubular tire mount. Clincher rim is little deeper (about 5-6 mm) than tubular rim (3-4 mm). So I worry the most is that tubular will come of the rim on very tight corner;/


Are you a composites engineer? You _think_ you repaired the rim, but what you actually did was remove the outer bead - which stiffens the sidewall - and put some reinforcement on the inside of the rim, when the rim has broken toward the outside. How did you ensure good bonding with the inside of the rim? How much sanding and acetone did you do before you laid down an epoxy that doesn't have the temperature rating for braking?

It doesn't sound like you did anything to actually address the rim problem, and you don't quite realize that. Composite rims are very difficult to make, and NO ONE who repairs carbon fiber will work on them.

As far as gluing, it also doesn't sound like you're going to have enough surface area with square clincher profile for good lateral bonding - I wouldn't corner on this tire.


There's a big difference between getting away with something for a little while and it actually being a good idea.


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## centurionomega (Jan 12, 2005)

*about $5000 a pop*



slowdave said:


> How much are you teeth worth?


I had an incident where my CF fork snapped due to operator error (sideswiping a chain link fence).

I landed on my face knocking out two teeth.

So far, the implants have cost $6100 and that is only for the titanium posts screwed into my maxilla.

The final crowns are going to be about $2000 each. One could really buy a nice set of wheels for $10,000.

Oh yeah, no dental insurance either.:cryin:


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## SixStringMadness (Aug 13, 2012)

Can someone explain the difference between clincher and tubular wheelsets for a noobie?


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## cxwrench (Nov 9, 2004)

SixStringMadness said:


> Can someone explain the difference between clincher and tubular wheelsets for a noobie?


in the illustration below, the rim/tire on the left is a tubular. the 2 on the right are clinchers. the tubular tire has a tube sewn inside the casing. the tire is glued onto the rim. 

with clinchers (the 'normal' tire that comes on virtually every bike sold today) the tire and tube are separate parts, and the tire has a 'bead' that locks into the 'hook' of the rim and holds the tire on when inflated. 

tubulars are generally lighter, and offer better ride quality as well as being nearly pinch-flat resistant. when you watch a big pro race like the tour, damn near every bike you see is on tubulars. an added advantage of tubulars is that if you do flat, the tire will stay on the rim allowing you to stop w/o crashing (hopefully). this is not always the case w/ clinchers, which can come off the rim. good quality tubular tires are somewhat more expensive, and when you flat one you need to pull the hopefully well glued tire off the rim (pain in the *ss) and put another tire on, then ride home carefully. so, you have to carry a spare tire w/ you when riding. 
with clinchers, you remove the punctured tube, find the cause of the puncture, remove the offending object if there is one, throw a new tube in and continue w/ your ride. 

weight differences can be substantial...i have edge carbon tubulars and clinchers. the tubulars weigh 1100g, the clinchers are 1350.


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## SixStringMadness (Aug 13, 2012)

Thanks for the info! I appreciate the great explanation. thanks


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## ntb1001 (Jan 19, 2010)

I agree with the ones saying it's not safe...you might have successfully(??) repaired the carbon, but from your description I don't know if the rim is shaped correctly for a safe tubular tire installation....for the price of some replacement rims & rebuild....I wouldn't chance it.


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## jneilt (Aug 11, 2012)

centurionomega said:


> I had an incident where my CF fork snapped due to operator error (sideswiping a chain link fence).
> 
> I landed on my face knocking out two teeth.
> 
> ...


If it makes you feel better, dental insurance generally does not cover implants and crowns on accident related incidents.

I have good insurance, no coverage for this...I had 8 and 9 replaced...I paid about 5K for the posts and crowns were about 5K as well. I am married to a dentist.

I would not ride that wheel.


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## DrSmile (Jul 22, 2006)

The fact that you are repeatedly using the word "grinded" makes me conclude that minding the details is not your forte. And it also explains the motivation for trying this hair-brained idea in the first place.


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## cxwrench (Nov 9, 2004)

DrSmile said:


> The fact that you are repeatedly using the word "grinded" makes me conclude that minding the details is not your forte. And it also explains the motivation for trying this hair-brained idea in the first place.


hey, you never know...it some parts of the world composite engineering and design may be taught before grammar and spelling.


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## Ppopp (Jun 20, 2011)

I don't know how you can be sure that the epoxy resin and carbon fiber that you used for the repair is compatible with material used in the original construction. Are you certain that they have the same coefficient of thermal expansion? If not, what's going to happen when you brake hard for the first time? Here's a hint: Kaboom!

There's about a million reasons that this isn't a good idea.

At least take your bike to a grassy area to test them out for the first time. And then ride down a grassy hill to see if they hold up under high-speed heavy braking. Try the rear wheel first. It will be easier to control your crash if you blow up the rear wheel.

Oh - and wear a helmet cam when you take the first test ride.


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## senji (Aug 14, 2012)

thank you for all your replies! it ensure me that it is sick idea like I said I got that wheels for nearly free so it was kind of challange. I guess that the best way will be to replace the broken/repaired rim for the new one - this time tubular :idea:


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## danl1 (Jul 23, 2005)

cxwrench said:


> weight differences can be substantial...i have edge carbon tubulars and clinchers. the tubulars weigh 1100g, the clinchers are 1350.


250 g for the wheelset. 

What's the weight difference between carrying a tube, and carrying a tubular tire?

/Not really interested in a battle of the maths where you pick the lightest possible tire and the heaviest possible tube, and I do the opposite. Just saying that in the real world, those "substantial" weight savings end up being not very much at all. And as you rightly point out, a well-glued tub is a pain to replace roadside. Avoiding pinchflats is nice, but I can't recall the last time I pinched. Maybe if I ran them way too low, or way too narrow...

There are reasons for professional racers with team cars to ride tubulars. For mortals, the reasons are a bit esoteric.


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## cxwrench (Nov 9, 2004)

danl1 said:


> 250 g for the wheelset.
> 
> What's the weight difference between carrying a tube, and carrying a tubular tire?
> 
> ...


i don't use them for training much, for obvious reasons. for racing, i'm not carrying a spare. and the spare doesn't rotate. i'm just talking about the differences between carbon clinchers and tubulars. if you compared carbon tubulars to a similar aero shape alloy rim the difference would be huge, up to 800g. that's noticeable to anyone. 
i never pinch flat either and we have some surprisingly crappy pavement for an area that never freezes or see any snow. i guess if you're just riding along not paying attention to the road at all you could, but i literally can not remember the last time i pinch flatted on the road. not sure it's ever happened to me in 30yrs.


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## jneilt (Aug 11, 2012)

centurionomega said:


> I had an incident where my CF fork snapped due to operator error (sideswiping a chain link fence).
> 
> I landed on my face knocking out two teeth.
> 
> ...


I can't send PMs or I would have replied...in short...

Stay safe, take care of the teeth, you really will want them in good shape later in life, if you have not lost a lot of color in the tooth that needs the canal...you might look into getting that done asap.


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## SirVelo' (Aug 16, 2012)

danl1 said:


> 250 g for the wheelset.
> 
> What's the weight difference between carrying a tube, and carrying a tubular tire?
> 
> ...



even if the tubular set up with a spare ire as opposed to a spare tube was the same weight...the tubulars would have les rotating weight which translate into a more significant weight loss. It is more efficiant, and have the effect of less weight. I have clicher, tubless clincher, and tubular wheelsets, the tubular wheels are by far my favorite, followed by the tubless. then lastly...the clincers....although I like all of them.


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## danl1 (Jul 23, 2005)

cxwrench said:


> i don't use them for training much, for obvious reasons. for racing, i'm not carrying a spare. and the spare doesn't rotate. i'm just talking about the differences between carbon clinchers and tubulars. if you compared carbon tubulars to a similar aero shape alloy rim the difference would be huge, up to 800g. that's noticeable to anyone.
> i never pinch flat either and we have some surprisingly crappy pavement for an area that never freezes or see any snow. i guess if you're just riding along not paying attention to the road at all you could, but i literally can not remember the last time i pinch flatted on the road. not sure it's ever happened to me in 30yrs.


Which was kind of the point I was getting toward - while they make arguable sense for racing, for training / everyday riding it's a bit silly, IMO. Saying they're needed / necessary / useful because of pinch flats (a common 'reason' given for non-racers using them) is saying that they're useful because you're tool lazy to keep your tires aired or pay attention to where you ride. So I wasn't really meaning to take you to task - more that your post presented a launch point for the other side of the story.

We'll just have to agree to disagree about the 'rotating weight' thing, rather than bothering with the copy/paste from any of the gazillion threads on the topic.


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