# Deep carbon rims in mountains



## CashMoney (Feb 28, 2012)

With the way carbon wheels are advancing in technology and quality is there any reason besides weight to not use a 50 or 60mm deep carbon wheel in the mountains?


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## coachboyd (Jan 13, 2008)

I would definitely use something around 50mm deep no problem. . although it would depend on the shape of the rim.

60mm, I use our 60mm rims in the mountains at times. . .but it depends on the mountains, the wind conditions, and even what tire I am running. If I am riding in the mountains, I am on at least a 25mm wide tire for better handling and cornering. 25mm tires really affect how the wind goes around the rim and tire in higher yaw angle situations. 

The main mountain I ride around here is Paris Mountain, which has a long downhill ridge run that is exposed to the west side. Basically, it's testing the situation where gusts of crosswinds will affect the bike the most. On a windy day, riding any 60mm deep wheel, it can be a bit unnerving when a gist of wind catches the bike at 40+mph. Of course, this would get a lot better with a 23mm tire. . .but then descending a mountain on 23mm tires loses a lot of advantage for handling.

By going a little shallower with the wheel, it really helps with controlling the bike in gusty wind and faster speeds. . .and allows you to run the larger tire for event better handling.

On days where there is no wind (dog days of summer), I regularly ride 60mm depth in the mountains. I still feel like the shallower gives an advantage in handling, and it feels better climbing as well.


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## ericm979 (Jun 26, 2005)

Many racers including me in the Everest Challenge (2 days, 29,035' of climbing) use roughly 50mm deep carbon rims. There's some flat sections and the aero helps a little on the descents... enough by my calculations to outweigh a certain amount of extra weight.

The one issue with carbon clinchers is braking heat. If you brake a lot due to very steep technical descents or not being confident or getting stuck behind slow traffic you can overheat the rim and cause it to melt and the tire to come of the rim. 

I've used carbon clinchers on many mountain rides without issue. I've been blown around on a couple but that was with older narrow V section rims which are affected more by cross winds, and very windy days.


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## MMsRepBike (Apr 1, 2014)

wind. 

If you're lightweight the wind is a consideration. 

Otherwise if they're quality wheels it's all good.


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## Lelandjt (Sep 11, 2008)

I use a 38mm front, 50mm rear carbon wheelset, both 23mm wide. It's a good balance of aero and handling in gusty winds.


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## TmB123 (Feb 8, 2013)

I'd agree with the others. I have a set of Zipp 202FC and 404FS wheels. Weight wise and climbing I don't really notice any difference. Climbing with wind there is a little bit of push with the 404's but nothing to worry about. High speed descents are another matter though, the 202's aren't really effected at all, the 404's on the other hand can be a handful. A few times I have been caught out mid corner with the change of direction of wind, with the bike cranked over hard I felt like I was going to crash, can be hard to hold a line into a corner sometimes etc but I guess because it is often unpredictable it is hard to know when it is going to happen so it can really hurt the confidence etc. I'd rather be thinking about riding than worrying about which side of the road I am going to end up on. The higher the speed, the more dramatic the effect.

If I had to choose one set between the two it would probably be the 202's. Awesome all round wheel, easier to live with in all comditions and probably has an edge on handling.


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## Jay Strongbow (May 8, 2010)

The question should be is there any reason to use them. I can't think of one. Maybe if you plan to race someone down.


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## MMsRepBike (Apr 1, 2014)

Jay Strongbow said:


> The question should be is there any reason to use them. I can't think of one. Maybe if you plan to race someone down.


So you can look cool like the kids.


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## Lelandjt (Sep 11, 2008)

Jay Strongbow said:


> The question should be is there any reason to use them. I can't think of one. Maybe if you plan to race someone down.


So you don't have to own multiple wheels and switch them around depending on where you're riding and the weather.


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## Jay Strongbow (May 8, 2010)

Lelandjt said:


> So you don't have to own multiple wheels and switch them around depending on where you're riding and the weather.


Because he said 50-60 and advancing rather than naming a specific depth and specific rim I assumed he was talking about buying wheels to use in the mountains. Not take a trip to the mountains with wheels he already owns.


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## Marc (Jan 23, 2005)

MMsRepBike said:


> So you can look cool like the kids.


Basically. Last few years on Tour de Nebraska several people have shown up with 50-60mm carbon rims....which when you know and have experienced the joyful surface Great Plains winds makes for instant WTF.

FWIW, they're almost never the first ones to camp.


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## sandiegosteve (Mar 29, 2004)

Given quality resins (I assume deep carbon wheels), wind is the big factor as mentioned.

I have 2 sets of wheels on different bikes. A pair of Shimano C24 Dura Ace that are very light, and a pair of Boyd 44mm. 

On average, I can't tell the difference climbing. Times up my normal routes very by a handful of seconds over a 20 minute climb between the wheels. Interestingly, the deep wheels have been the fastest of a 1 mile 7.5% climb out of the tidepools I like. I think other factors play a bigger part, but for constant effort climbing, there is no penalty or advantage I can tell. 

The Shimano's accelerate very quickly, but I don't do major accelerations when climbing that much.

When it gets windy, as others have mentioned, the deeper models require more attention.

I find that my deep wheels are very stiff, and I like that. I'm super happy with my Boyd's for both hills and flats.


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## CashMoney (Feb 28, 2012)

Jay Strongbow said:


> The question should be is there any reason to use them. I can't think of one. Maybe if you plan to race someone down.


Let me clairify....Where I live I ride flat to rolling hills to mountains in Boise Idaho so I would rather have one set and preferable a deep wheel for an all around and not changing to different wheels for different rides. So just looking for what opinions are out there.


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## TmB123 (Feb 8, 2013)

I know it's not what you want to hear, but if I had to choose one set only of "do it all" wheels, it would be a shallower one.


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## deviousalex (Aug 18, 2010)

Quality carbon/resin is key and should not be understated. Nearly all friends of mine who have bought these Chinese wheels have had the braking surface warp and delaminate from the continuous heating/cooling cycles.


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## Lelandjt (Sep 11, 2008)

TmB123 said:


> I know it's not what you want to hear, but if I had to choose one set only of "do it all" wheels, it would be a shallower one.


Yeah, I'm liking my 38s better than my old 50s. But now I'm considering 38 front, 50 rear.


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## TmB123 (Feb 8, 2013)

I've considered just throwing my 202 on the front for windy days but the brake tracks arent quite the same between the two sets of wheels so it's not quite that easy.

for the OP, something like a Shimano C35, 202/303, Enve 3.4 (I think that's what they are) or any of the other nice wheelsets around that 35mm ish depth would probably be the sweet spot for you.

deep rims look cool and are fast in a straight line, but you shouldn't have to "put up with" the shortcomings if it is your only set.


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## Marc (Jan 23, 2005)

deviousalex said:


> Quality carbon/resin is key and should not be understated. Nearly all friends of mine who have bought these Chinese wheels have had the braking surface warp and delaminate from the continuous heating/cooling cycles.


Quality runs into big bucks....and most people aren't to keen on spending more for a set of bicycle wheels than on their teenage beater car.


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## CashMoney (Feb 28, 2012)

Marc said:


> Quality runs into big bucks....and most people aren't to keen on spending more for a set of bicycle wheels than on their teenage beater car.


I would never buy Chinese carbon rims but I do think that you can get a quality carbon wheel set in the 1500 range which imo isn't bad


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## Lelandjt (Sep 11, 2008)

Marc said:


> Quality runs into big bucks....and most people aren't to keen on spending more for a set of bicycle wheels than on their teenage beater car.


Cheap rims are for people who don't put much heat into them. I've seen people dragging brake down a long hill on carbon clincher Zipps and thought I'd never dare do that on my Chinese. Then again, fear of going slow already keeps me off the brakes.


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## deviousalex (Aug 18, 2010)

Marc said:


> Quality runs into big bucks....and most people aren't to keen on spending more for a set of bicycle wheels than on their teenage beater car.


Then carbon rims aren't for you. There's no such thing as a free lunch.


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## Marc (Jan 23, 2005)

deviousalex said:


> Then carbon rims aren't for you. There's no such thing as a free lunch.


Very true.

Ofc I don't ride CF clinchers now and don't intend to. The price is ridiculous, the gains minimal for anyone not racing, they're a terrible choice for Great Plains windage, and they're a great way to ugly up an otherwise nice looking bike anyway


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## DaveLeeNC (Jan 12, 2011)

It seems to me that if you are riding a route that is dominated by mountains, then deeper rims really are not such a good choice. 

1) When climbing aero is of marginal advantage as you are mostly just overcoming gravity

2) When descending in very light winds your yaw angle will always be very small, so the aero advantage is not much (given the data that I have seen). If there is enough wind to generate a reasonable yaw angle on a fast descent, then there are other issues WRT the deep wheel. 

IMHO.

dave

ps. I do recall one tire manufacturer doing some kind of analysis that said that there is still an advantage for aero over weight even in 'the mountains'. So maybe my qualitative analysis is wrong here.


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## Jay Strongbow (May 8, 2010)

DaveLeeNC said:


> It seems to me that if you are riding a route that is dominated by mountains, then deeper rims really are not such a good choice.
> 
> 1) When climbing aero is of marginal advantage as you are mostly just overcoming gravity


If your point is that having 'aero' wheels aren't going to amount to anything that impacts your riding and results you're right.

But scientifically speaking your wrong. An aero advantage is always present and is actually greater at slower speeds if the measurement is time saved over a specific course. It's hard to grasp (or was for me) but it's true. The MPH increase is greater at higher speeds but the slower person spends more time on the course so is helped more in terms of time. 
I'm not trying to argue with deep aero wheels not making sense for mountain riding though. Completely agree with that.


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## DaveLeeNC (Jan 12, 2011)

Jay Strongbow said:


> If your point is that having 'aero' wheels aren't going to amount to anything that impacts your riding and results you're right.
> 
> But scientifically speaking your wrong. An aero advantage is always present and is actually greater at slower speeds if the measurement is time saved over a specific course. It's hard to grasp (or was for me) but it's true. The MPH increase is greater at higher speeds but the slower person spends more time on the course so is helped more in terms of time.
> I'm not trying to argue with deep aero wheels not making sense for mountain riding though. Completely agree with that.


Just for grins here is a quicky "analysis". I used the calculator at An interactive, model-based calculator of cycling power vs. speed . Assume that a rider is pedaling up a very long, 10% grade at 275W. Per the calculator the drag component of the forces being overcome is 2%. Further assume that the wheels contribute 15% of the drag and that these deep wheels will reduce that to zero (unlikely in the extreme, but ..). 

So the net gain is 2% x 0.15 = 0.3%, or for a 20 minute climb (that just happened to have the PERFECT wind speed/angle to generate the optimum YAW angle on magic wheels  ) you gain 3.6 seconds on your 20 minute climb.

Like I said - marginal :wink5:

dave


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## Jay Strongbow (May 8, 2010)

DaveLeeNC said:


> Just for grins here is a quicky "analysis". I used the calculator at An interactive, model-based calculator of cycling power vs. speed . Assume that a rider is pedaling up a very long, 10% grade at 275W. Per the calculator the drag component of the forces being overcome is 2%. Further assume that the wheels contribute 15% of the drag and that these deep wheels will reduce that to zero (unlikely in the extreme, but ..).
> 
> So the net gain is 2% x 0.15 = 0.3%, or for a 20 minute climb (that just happened to have the PERFECT wind speed/angle to generate the optimum YAW angle on magic wheels  ) you gain 3.6 seconds on your 20 minute climb.
> 
> ...


For some reason I thought (imagined) that you said "no gain" when climbing and decided to get pedantic about it......but you very clearly didn't say that so my mistake. Sorry 'bout that.


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## deviousalex (Aug 18, 2010)

DaveLeeNC said:


> 2) When descending in very light winds your yaw angle will always be very small, so the aero advantage is not much (given the data that I have seen). If there is enough wind to generate a reasonable yaw angle on a fast descent, then there are other issues WRT the deep wheel.


Are you saying that aerodynamic rims only matter in crosswinds?


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## DaveLeeNC (Jan 12, 2011)

deviousalex said:


> Are you saying that aerodynamic rims only matter in crosswinds?


The data from Flo Cycling here 

FLO Cycling - Wind Tunnel Results and Cycling Wheel Aerodynamics Tutorial

specifically the chart below is typical of what you see from aero wheels. Setting aside the old 32 spoke Mavic's, note that at 0 degrees YAW angle (which is what you will always encounter when going in a straight line in zero wind) the aero advantage is very small. 

dave


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## deviousalex (Aug 18, 2010)

DaveLeeNC said:


> The data from Flo Cycling here
> 
> FLO Cycling - Wind Tunnel Results and Cycling Wheel Aerodynamics Tutorial
> 
> ...


Right, but it still shows that aerodynamics do matter in a straight line. Their 30mm rounded rim profile shows a decent difference to the box section open pro.


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## DaveLeeNC (Jan 12, 2011)

deviousalex said:


> Right, but it still shows that aerodynamics do matter in a straight line. Their 30mm rounded rim profile shows a decent difference to the box section open pro.


That is true, but in the context of this thread (of 'going deep' in rims in the mountains) all the data that I have seen shows a very limited advantage to deeper at very low yaw angles. But there are other parameters at play, particularly if you compare much older designs. 

dave


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## November Dave (Dec 7, 2011)

Bear in mind that FLO removes the rare from their results. In short, they run the rig with no wheel in the fixture, then run the rig with the wheel in the fixture, and then subtract a from b to get their stated result. As I understand it, the Open Pro in this graph was not run 'same test, same day, same protocol.' So the 0* numbers are actually much closer than shown here. 

Based on a huge amount of weather condition research and knowledge (I have an extensive sailboat racing background), the yaw angles you'll actually experience in riding where aero 'really counts'* are between zero and ten. That can be argued but Trek has an excellent study that agrees, and the other most credible studies of it that we've seen agree wholeheartedly. A recent podium placer at Ironman Kona, who is a Specialized athlete (or was at the time I spoke to him about it) and had plenty of access to tunnel time, told me he only tested between -10* and +10* yaw. His race speeds are similar to what you do on a fast group ride or race. 

*aero always 'counts,' but when you're going fast it is more strongly felt.


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## TmB123 (Feb 8, 2013)

It's interesting that the one thing that makes an aero wheel most effective (crosswinds) is the same thing that makes them almost impossible to use at high speed and take advantage of them due to the way they effect bike handling, rider confidence etc. And I'm talking about high speed mountain descents, not cruising the flats.

Something else I have noticed with my wheels that I have never heard mentioned is that on the few occasions where I have drafted a car at reasonable speed, the bike feels like it gets speed wobbles. They obviously don't like the turbulent air coming off the car. Not sure if that is just something with my particular wheel or more common to a deeper wheel in general.


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## November Dave (Dec 7, 2011)

Could be your wheel or your bike or any number of things, but that's not inherent to deep wheels, no. Not at all. 

Some relatively recent classics standout/GT domestique (I think it was Stefan Wesseman but its more likely I'm wrong) said the guys in his league - the ones who could climb near the front but who could climb well enough to get back on with a baller descent - always used shallow wheels on climbing days to have absolute confidence on descents. I wish I got to do that kind of riding more than I do, but like most people, I don't.


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## TmB123 (Feb 8, 2013)

November Dave said:


> Could be your wheel or your bike or any number of things, but that's not inherent to deep wheels, no. Not at all. .


Thanks - I've never had a speed wobble in my life riding all sorts of bikes and regularly hitting speeds in the order of 100 kph, it has only been since putting these particular wheels on my bike, so its either the wheels, or the wheels interacting with my particular bike setup when in the draft of a vehicle. I guess when you design wheels to work in a certain way that when the airflow isn't necessarily playing by the rules, either does the way the wheel behaves.


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## DaveLeeNC (Jan 12, 2011)

November Dave said:


> SNIP
> 
> Based on a huge amount of weather condition research and knowledge (I have an extensive sailboat racing background), the yaw angles you'll actually experience in riding where aero 'really counts'* are between zero and ten. That can be argued but Trek has an excellent study that agrees, and the other most credible studies of it that we've seen agree wholeheartedly. A recent podium placer at Ironman Kona, who is a Specialized athlete (or was at the time I spoke to him about it) and had plenty of access to tunnel time, told me he only tested between -10* and +10* yaw. His race speeds are similar to what you do on a fast group ride or race.
> 
> *aero always 'counts,' but when you're going fast it is more strongly felt.


Do you have a link to any of the studies that you referenced above regarding YAW angle values 'in practice'. I just threw together (in the most literal sense) a quickie analysis that would apply to my riding 'in situations where I might care'. This would most likely be some kind of personal effort for a PR anywhere from 1 mile to 100 miles. In my terrain 1000 feet of climbing (or descent) per 25 miles is typical. My 50 mile PR is 21.4 mph.

So I just set up a model assuming 

- flat terrain

- 21 mph speed with no wind (or gradient)

- wind varies from 0 mph to 12 mph (any speed equally likely) 

- wind angle (actual windspeed relative to the bike direction of travel) varies from 0 to 360 degrees (any angle equally likely) 

- I made my best assessment as to how my bike speed would vary as a function of the headwind component of the actual wind 

Given those assumptions the average YAW angle came to 10 degrees and the median YAW angle came to 11 degrees. This is a whole lot closer to the point where aero wheels are typically optimized than I would have guessed.

Maybe you wheel designers really do know what you are doing 

FWIW.

dave


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## November Dave (Dec 7, 2011)

Thanks, and good calcs

You can use this calculator to run the calls you seem to have a handle on already (linked more for others than for you). Instead of boat speed, use bike speed (obvs), and keep both wind speed and wind angle as true (working backwards from apparent wind speed/angle is key in sailing, not so much in riding). All speeds there are referenced in knots, so multiply your given bike speeds by 1.15 to convert mph to knots. 

Section 3.2 of this is the Trek piece I referenced.

In reality, 12 mph is a fairly windy day in North America, especially at ground level. There is a pretty significant gradient effect nearly all the time. If it was blowing even 6mph at ground level, leaves and paper trash would be blowing around constantly, which you and I know doesn't happen. Also, people constantly comment that they ride around in 20mph winds. Unless you are in San Francisco, Maui, or near Hood River OR, in the summer, that's a big overestimation. Certain areas of the midwest on the plains are quite windy, but not that windy. Opening a car door into 20mph wind is challenging. White caps generally begin on open-ish bodies of water in the very low teens of wind speed. 

Also, you only need to go out from 0 to 180 in calcs - 181 to 360 is just a mirror of 0 to 180. Save some time.


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## asgelle (Apr 21, 2003)

November Dave said:


> Also, people constantly comment that they ride around in 20mph winds. Unless you are in San Francisco, Maui, or near Hood River OR, in the summer, that's a big overestimation.


A spring day I chose at random Weather History for Albuquerque, NM | Weather Underground Note wind speed above 20 mph from 11:00 AM to 8:00 PM.


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## November Dave (Dec 7, 2011)

Absolutely no intent on my part to say that wind speeds like that NEVER happen - of course they do, everywhere. They are just rare. The assertion I addressed was when people say that it 'always blows 20' where they ride.


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## Jay Strongbow (May 8, 2010)

November Dave said:


> In reality, 12 mph is a fairly windy day in North America, especially at ground level. There is a pretty significant gradient effect nearly all the time. If it was blowing even 6mph at ground level, leaves and paper trash would be blowing around constantly, which you and I know doesn't happen. Also, people constantly comment that they ride around in 20mph winds. Unless you are in San Francisco, Maui, or near Hood River OR, in the summer, that's a big overestimation.


You might want to let NOAA know about that. I always check the weekend weather on Friday and 20mph is common and 12ish or more seems to be the rule more than the exception. I live in Boston but usually check for some town out in the 'burbs.

By coincidence I just did my Friday weather check before reading this. 18-22 MPH with 37 MPH gusts on Sunday and not going below 12 until Monday night. I didn't make anything of it when I saw that because I'm very used to seeing similar when I check.

Or is "surface wind", which I believe if 10 meters up and what NOAA reports, really that different from ground level?


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## November Dave (Dec 7, 2011)

Boston is actually a very windy city, for one, and the surface wind really is that different from the wind 10 meters up in a clear and unobstructed zone. 

I spent 4 years of my life sailing about 160 days a year mostly in a town just outside of Boston (Arlington - Upper Mystic Lake, to be precise), and also on the Charles. I can absolutely assure you that 12mph wind is very much NOT the rule. If it were the rule, college sailors would not spend their entire lives trying to lose weight. A more weight obsessed crowd you will not find outside of the Tour. EDIT - I also have heard directly from the then-head of NOAA marine forecasting, who gave a talk at a safety at sea seminar I did, that their mandate is to forecast for SAFETY and not absolute ACCURACY. If there is a 30% chance that it will blow 15, they forecast the upper limit at 15 or more, even though it is statistically unlikely to blow that hard. 

The reason why I live (edited from 'love' although love works too) where I live (Newport, RI) is precisely because there is so much 'useful' wind here (loosely defined as above 8 knots during daylight hours during the 8 warmest months of the year). The specific area of the Sakonnet River near Fogland Light has more useful daily wind than nearly anyplace else in continental NA (you can verify this with a subscription to SailFlow). 12 mph breeze there is somewhat regular, but nothing even approaching all day every day. 

Just today I rode along the Sakonnet and got within .25 miles of the meter at which all of that is measured. To me and the two guys I was with, today was a windy day. It was not blowing more than 14 at ground level. On a totally exposed bridge about 100' off the water, which runs approximately 90* to today's wind direction, the draft zone was about 20* to 25* from the rider in front. It was WINDY on that bridge. That's something of an outlier situation. The rest of the time, the draft zone was within about 10* of the rider ahead. Even on a quite windy day, at a low endurance pace (avg speed around 17 - one guy had a rough day so we rode to his speed). 

North America just isn't very windy. But don't believe me. Read the Trek thing and as many other data points as possible.


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## Lelandjt (Sep 11, 2008)

I live on Maui and when it gets too windy to comfortably road ride I kiteboard so I'm pretty atuned to the wind. 15ish mph at ground level is about when that happens with 50mm V rims. With my 38mm bulgy rims 20mph is when I call it. 20 is pretty solid, really pushing you around when it bounces off cliff walls and allows me to use a pretty small kite. Oh yeah, that's another thing about riding in wind. On a plain where it's just a constant force from a stable direction it's much more managable than on the twisty roads with a rock wall on the inland side. You get buffetted so unpredictably that you have to slow below 15mph for safety. But really you should all come see for yourselves this winter. West Maui Cycles will rent you Dura-ace Tarmacs or Ultegra Roubaixs with shallow rims. If you get out early before the wind and sun get bad it's a cycling paradise.


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## DaveLeeNC (Jan 12, 2011)

November Dave, thanks for the link. Very interesting.

dave


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## November Dave (Dec 7, 2011)

Lelandjt - Thanks for that, and man I'm pretty jealous.

DaveLeeNC - You're welcome. I know that people are in general pretty guarded/skeptical about info coming from the industry and industry people, and generally with good reason. But if you look hard enough, there is some great info out there. Give Trek all the crap you want for whatever else, but their product development teams do nice work, they do a good job of showing their work, and we're not at all hesitant to learn from it and share it. It's like that old Sy Sims ad (for old people who live/lived around NY) - "educated consumers make the best customers." Their Aeolus D3 development paper is also quite good (and to me their shapes look quite good, which shouldn't be surprising when you look at a Rail). Make sure you read the footnotes and qualifiers on the wheels one, there are a bunch of them and they're important.


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## springs (Jun 26, 2011)

I remember Sy Syms! Maybe that's why I own a set of Rail 52s ;-)


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## threebikes (Feb 1, 2009)

Great posts and thanks for the links.


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## Moderate (Jan 9, 2016)

Jay Strongbow said:


> Or is "surface wind", which I believe if 10 meters up and what NOAA reports, really that different from ground level?


I think "surface wind" probably is very different. Consider the research here: lib.dr.iastate.edu/cgi/viewcontent.cgi?article=1655&context=abe_eng_pubs 

This would seem to indicate that, in an agricultural setting, wind speed at 1m is less than half of wind speed at 10m. Yet another reason to get an aerodynamic helmet before wheels: it sits higher off the ground!

Of course, you get into cities or mountains or forests or dense-ish suburbs and everything changes again.


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## DaveLeeNC (Jan 12, 2011)

Moderate said:


> I think "surface wind" probably is very different. Consider the research here: lib.dr.iastate.edu/cgi/viewcontent.cgi?article=1655&context=abe_eng_pubs
> 
> This would seem to indicate that, in an agricultural setting, wind speed at 1m is less than half of wind speed at 10m. Yet another reason to get an aerodynamic helmet before wheels: it sits higher off the ground!
> 
> Of course, you get into cities or mountains or forests or dense-ish suburbs and everything changes again.


Just for grins (if I get around to it) I think that I will build a (trivial) wind vane for my bike. This would be a pencil like stick that would be attached pointing straight up from somewhere forward of where turbulence from the bike begins (as best as can be done). This would probably be the stem. Then hang a very light piece of ribbon off it and as I ride (in theory) the ribbon would represent (in a crude and somewhat integrated form) the instantaneous yaw angle. 

Unless I really haven't gotten this thing out of the turbulence, which is what one of the links that November Dave so generously posted would indicate was Trek's experience. Maybe I could use a small dowel rod that would stick out to the left or right (would probably carry that so I could get it out of the way in traffic/etc). 

Just because I am curious about such things. 

dave


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## Marc (Jan 23, 2005)

Moderate said:


> I think "surface wind" probably is very different. Consider the research here: lib.dr.iastate.edu/cgi/viewcontent.cgi?article=1655&context=abe_eng_pubs
> 
> This would seem to indicate that, in an agricultural setting, wind speed at 1m is less than half of wind speed at 10m. Yet another reason to get an aerodynamic helmet before wheels: it sits higher off the ground!
> 
> Of course, you get into cities or mountains or forests or dense-ish suburbs and everything changes again.


Depends on where you are. There's farm country and then there's farm country.

Ride out in the Great Plains, where the road signs point out the nearest ranch and the elevation profile is mostly flat...and you get ridiculous surface winds that build over hundreds of miles of almost entirely empty land. Nothing for it but either not ride when the sun and wind are up for 6 months of the year, or HTFU. You can also have river valleys that act as wind tunnels making the obscene surface winds even worse.


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## Moderate (Jan 9, 2016)

Marc said:


> Depends on where you are. There's farm country and then there's farm country.
> 
> Ride out in the Great Plains, where the road signs point out the nearest ranch and the elevation profile is mostly flat...and you get ridiculous surface winds that build over hundreds of miles of almost entirely empty land. Nothing for it but either not ride when the sun and wind are up for 6 months of the year, or HTFU. You can also have river valleys that act as wind tunnels making the obscene surface winds even worse.


Absolutely, but I was making the point that the wind will be much lower near the ground (eg where the wheels are) than at 10 above ground.

And yes, the Great Plains have a lot of wind and presumably a lot fewer surface features to slow it down:









But even on the Great Plains I would expect the motion of air to be substantially slower at 1m than at 10m. The physics says that the air at ground level is moving with zero velocity and that it increases as you move away from the ground (up to the point where it is mostly unaffected by the ground). Of course, as the above map shows, you might be starting with a higher wind speed at 10m than in some places.


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## November Dave (Dec 7, 2011)

I've often thought of getting one of these, mounting it on the head tube, and pointing a GoPro down at it. That would be crude but easy, and give lots of real world info. Another option would be to take a masthead wind vane from a sailboat (I used to work for a company that made them - I'm not kidding when I say I've got a background in this stuff), and mount that. It might actually be possible at this point that there's a Bluetooth wireless masthead unit that could output a stream to a phone or Garmin, which you could then export into a usable file in order to make a plot. With what Trek went through in getting their data, they could have put together a much more elegant data collecting rig, but they got good info doing what they did. 

But all of that is going a long long way to find out what has already been found out for us.

Meters/second convert to mph at roughly 2.25 m/s to 1 mph. That's a great map/chart. If you overlay Strava heat maps on that, it's easy to see that where most people ride, it's really not that windy. And that map shows the wind at 30 meters elevation. That's high up, way windier up there than at ground level.


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## Marc (Jan 23, 2005)

Moderate said:


> Absolutely, but I was making the point that the wind will be much lower near the ground (eg where the wheels are) than at 10 above ground.
> 
> And yes, the Great Plains have a lot of wind and presumably a lot fewer surface features to slow it down:
> 
> ...



That is "average"...

During the summer, the rated windspeed here (measured at 10m) standard is 15-20 meters/second normally whereas during winter it tends to be dead still much of the time. The catch being the less obstructions there are, the less the wind breaks into layers so greatly where the wind at 10m is 20m/s and the ground level wind is 2 m/s and so the stratification model falls apart. You can see it on I-80 during summer, as the semi-trucks trailers fishtail due to wind. And if you pass a tractor trailer even in a compact, with the truck acting as a wind shadow, keeping control is very difficult Most people until they've ridden in it don't believe how bad the Great Plains winds are.


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## kjdhawkhill (Jan 29, 2011)

November Dave said:


> "Thanks, and good calcs
> 
> You can use this calculator
> 
> ...


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## kjdhawkhill (Jan 29, 2011)

If the average wind speed of a generic Midwestern town is 10 or 11 mph, I wouldn't describe a < 20% deviation as a rare occurrence. It may be "fairly windy," but that doesn't mean it's something one shouldn't account for if they plan on purchasing a $1800 wheelset.


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## November Dave (Dec 7, 2011)

To be clear, my original intent was to provide a counterweight to a lot of the claims that you hear from people that (to loosely paraphrase) "I ride X wheels in 20mph crosswinds all the time and it's no problem." Most places where most people ride simply don't have those kind of winds anything remotely close to "all the time." So I'm really advancing sort of the opposite viewpoint of the one I'm being credited with.

There are obviously places in the plains where winds are higher. However, if you overlay population density on the map shown, it would show that the vast majority of people live in areas with average wind speeds of under 10mph at 30 meters. A good (and conservatively high) estimate of ground winds is about 50% of that. If you overlay a Strava heat map on top of the wind speed map, you'd see that most cycling is done in light wind environments. And an overlay of our sales would certainly correspond with that as well (although we sell a ton of wheels in Texas).

So the big takeaway is that when someone tells you "I ride in crazy crosswinds all the time and deep wheels are no problem," that should be taken with an extra large grain of salt. 

Here's a video of a somewhat windier than typical summer day in Hood River. It smokes there during the summer. If you go there again, notice that almost every door that faces north or south is hinged on the west side - even up in town. That's so the doors don't get blown off the hinges when you open them. It's a REALLY REALLY windy place.


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## Mackers (Dec 29, 2009)

November Dave said:


> ...Meters/second convert to mph at roughly 2.25 m/s to 1 mph...


You mean 5mph, right?


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## November Dave (Dec 7, 2011)

Yeah, should have been 2.25 mph = 1 m/s. On the US wind speed chart, double the m/s values to get mph (which I'd been doing in my head throughout - disconnect from brain to fingers happens occasionally).


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## TmB123 (Feb 8, 2013)

November Dave said:


> So the big takeaway is that when someone tells you "I ride in crazy crosswinds all the time and deep wheels are no problem," that should be taken with an extra large grain of salt.


I've always assumed that most people that write reviews on deep wheels must ride with magic wind.


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## Lelandjt (Sep 11, 2008)

Some people seem more immune to it. Some of the top Iron Man racers use crazy deep wheels in gnarly wind and look stable enough, and they're fast. Plenty of other tri-racers try to copy them and get blown off into the lava fields.


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## TmB123 (Feb 8, 2013)

I think to some degree it depends on WHERE you use them, rolling along on a flattish wide-ish highway probably not so much of an issue being pushed around, bombing down a narrow winding hillside or ridgeline, sh1t gets serious! But yeah, some people do handle it better than others too.


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