# Does anyone run a mix of wheel depths?



## TricrossRich (Mar 26, 2014)

I'm currently running 50mm deep wheels on my Venge. I am about to start building up an Allez to use for crit racing and at first I was going to buy 60mm wheels, but then last night I realized i could get a 38mm front and 60mm back.. I would then run the 50 front/ 60 rear on the Venge and the 38 front/50 rear on the Allez. Is there any advantage to doing something like this? Do people do this? Several friends of mine have both Zipp 303's and 404's and occasionally they run a 303 front, 404 rear and call it a 304.

The only obvious advantages I can see is that running a smaller front would save some weight, compared to a front of the same depth as the rear. It would also be less susceptible to wind gusts. The downside being that the front wheel is slightly less aerodynamic. Any effects on handling I should be aware of? Thoughts.


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## NealH (May 2, 2004)

I think the main thing is that in a crit race there may be more disadvantages to using deep dish carbon wheels than advantages. As you mentioned, handling suffers with wind gusts. In close quarters racing, I would think the less susceptible the better. In addition, carbon wheel braking becomes flaky when wet. Maybe crit races are stopped when it starts raining but if not, then that may be a good reason for not putting carbon wheels on the bike. Deep dish carbon wheels are typically a little heavier than quality metal rim wheels like the Dura Ace C24. An argument could be made that the lighter clincher box rim will accelerate better thus providing a slight advantage due to all the dynamics involved in a crit race. However, the better aero properties may trump the weight penalty. I think the wet braking would be my biggest concern, and the wind sheer effects are the second concern. Otherwise, they should work well, or at least as good as a C24 wheel set.


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## SwiftSolo (Jun 7, 2008)

The 3.4 in Enve 3.4 stands for a 35mm front and a 45mm rear deep wheels. The narrower front does seem to me to reduce the torsional steering force that occurs in puffy cross winds as compared to my zipp 303's


TricrossRich said:


> I'm currently running 50mm deep wheels on my Venge. I am about to start building up an Allez to use for crit racing and at first I was going to buy 60mm wheels, but then last night I realized i could get a 38mm front and 60mm back.. I would then run the 50 front/ 60 rear on the Venge and the 38 front/50 rear on the Allez. Is there any advantage to doing something like this? Do people do this? Several friends of mine have both Zipp 303's and 404's and occasionally they run a 303 front, 404 rear and call it a 304.
> 
> The only obvious advantages I can see is that running a smaller front would save some weight, compared to a front of the same depth as the rear. It would also be less susceptible to wind gusts. The downside being that the front wheel is slightly less aerodynamic. Any effects on handling I should be aware of? Thoughts.


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## TricrossRich (Mar 26, 2014)

NealH said:


> I think the main thing is that in a crit race there may be more disadvantages to using deep dish carbon wheels than advantages. As you mentioned, handling suffers with wind gusts. In close quarters racing, I would think the less susceptible the better. In addition, carbon wheel braking becomes flaky when wet. Maybe crit races are stopped when it starts raining but if not, then that may be a good reason for not putting carbon wheels on the bike. Deep dish carbon wheels are typically a little heavier than quality metal rim wheels like the Dura Ace C24. An argument could be made that the lighter clincher box rim will accelerate better thus providing a slight advantage due to all the dynamics involved in a crit race. However, the better aero properties may trump the weight penalty. I think the wet braking would be my biggest concern, and the wind sheer effects are the second concern. Otherwise, they should work well, or at least as good as a C24 wheel set.


I'm not too concerned with the wet braking properties.. I have aluminum rims I can run in the wet... IME, a good carbon wheel even deep depth is still lighter than a "light" aluminum option.


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## TricrossRich (Mar 26, 2014)

SwiftSolo said:


> The 3.4 in Enve 3.4 stands for a 35mm front and a 45mm rear deep wheels. The narrower front does seem to me to reduce the torsional steering force that occurs in puffy cross winds as compared to my zipp 303's


Swift... hmmm. I didn't realize that was how Enve named their wheels, but sure enough you're right. and I see that the 6.7's are a 60mm front, 70mm rear. very interesting. I did a little research and see that Reynolds also has some mixed sets as well, so i think I made up my mind. It gives me more options. Thanks guys...


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## craiger_ny (Jun 24, 2014)

TricrossRich said:


> i think I made up my mom


lol .


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## SauronHimself (Nov 21, 2012)

NealH said:


> I think the main thing is that in a crit race there may be more disadvantages to using *deep dish* carbon wheels than advantages.












Mastering Wheel Dishing - Wheel Fanatyk


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## 195cranky (Jun 25, 2013)

Have Flo Cycling 30's, 60's, 90's, and rear disc for TT. Can swap front and rears as needed. Can run 30/30, 30/60, 60/60, on TT 60/90, 90/90, 60/disc, or 90/disc. A whole quiver for much less than costs of some Zippy pricey wheely fleet. Great to have choices and to match up to any riding or wind conditions.


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## crit_boy (Aug 6, 2013)

Discussion (and tests) of same front/back and the mullet (no flock of seagulls) on November cycles. Here. Interesting stuff.


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## TricrossRich (Mar 26, 2014)

crit_boy said:


> Discussion (and tests) of same front/back and the mullet (no flock of seagulls) on November cycles. Here. Interesting stuff.


hmmm... interesting.


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## cxwrench (Nov 9, 2004)

SwiftSolo said:


> The 3.4 in Enve 3.4 stands for a 35mm front and a 45mm rear deep wheels. The narrower front does seem to me to reduce the torsional steering force that occurs in puffy cross winds as compared to my zipp 303's


It's _shallower or deeper_, not _wider or narrower_. The front rim on Enve's Smart system wheels is actually _wider_ than the rear, it is also _shallower in cross section_. 

Proper terminology is important these days.


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## SwiftSolo (Jun 7, 2008)

You are correct. On the other hand, I doubt the op was confused by my last sentence referring to the impact of cross wind on a narrower (profile) rim--especially in view of the first sentence.


cxwrench said:


> It's _shallower or deeper_, not _wider or narrower_. The front rim on Enve's Smart system wheels is actually _wider_ than the rear, it is also _shallower in cross section_.
> 
> Proper terminology is important these days.


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## froze (Sep 15, 2002)

It's funny thing those deep wheels, what's so funny you scream? Funny in that the front wheel catches all the wind and rear is being protected and getting garbage wind by the bike frame and the person on the bike so put the most aero rim on the rear where the advantage is almost negated? Of course a 60mm rim in the front could present a problem in strong cross winds depending on how it's made, but it's not a disk so it won't be impossible to handle, but for the most aero advantage the 60 should be in the front.


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## CrankyCarbon (Dec 17, 2014)

I side wind will cause havoc to a TT run with a rear disc even if the front is very shallow. I've been blown around before with a rear disc, so it's not just the front. But I've been blown around from the front in the case when I used to use Spinergy Rev-X's. I haven't had a major issue with my Mavic Cosmic Carbones. So it may depend upon your total setup and where the wind is coming from and how much it's blowing.

It'll be interesting with the wind when I try the TriSpoke/Disc combo in the spring.


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## TricrossRich (Mar 26, 2014)

SwiftSolo said:


> You are correct. On the other hand, I doubt the op was confused by my last sentence referring to the impact of cross wind on a narrower (profile) rim--especially in view of the first sentence.


Yes, I understood the point you were trying to make.



froze said:


> It's funny thing those deep wheels, what's so funny you scream? Funny in that the front wheel catches all the wind and rear is being protected and getting garbage wind by the bike frame and the person on the bike so put the most aero rim on the rear where the advantage is almost negated? Of course a 60mm rim in the front could present a problem in strong cross winds depending on how it's made, but it's not a disk so it won't be impossible to handle, but for the most aero advantage the 60 should be in the front.


Yes, from a strictly aerodynamic point of view, you're probably right, but we've got to think about all of the pluses and minuses.


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## froze (Sep 15, 2002)

TricrossRich said:


> Yes, I understood the point you were trying to make.
> 
> 
> 
> Yes, from a strictly aerodynamic point of view, you're probably right, but we've got to think about all of the pluses and minuses.


I don't think the plus and minuses are as much as you think, here are a couple sites that discuss this rational; see: road bike - 38mm Front 60mm Rear Clinchers Pros and Cons - Bicycles Stack Exchange
aero wheel wisdom - Bike Hugger


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## SwiftSolo (Jun 7, 2008)

I think the thing to remember is that wind tunnel testing on bikes is as much about marketing as it is about science. Testing aerodynamics of bikes or components without a rider on board pedaling is purely about marketing hype.

Anecdotal experience seems to support the idea that the impact of the severe crosswind gusts that sometimes occur when roads cross mountain side canyons are more problematic on wide profile front wheels. It's my experience that even heavy, somewhat steady crosswinds are far less frightening on those wheels.

I suspect that the common wheel width differential is driven more by this factor than by simple drag considerations.


froze said:


> I don't think the plus and minuses are as much as you think, here are a couple sites that discuss this rational; see: road bike - 38mm Front 60mm Rear Clinchers Pros and Cons - Bicycles Stack Exchange
> aero wheel wisdom - Bike Hugger


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## bikerector (Oct 31, 2012)

A lot of people run a deeper rear than the front. The front is more affected by cross winds and thus the shallower rim to reduce the effects of having handling issues. The rear wheel, while getting a lot of the same side force as the front (if the rim depths were identical), the rear doesn't pivot around an axis, the fork, and approximately 70% of your weight is in the rear wheel. 

There's also the fact that if the rear slides, blows, is misdirected some, it's generally far easier to control than if the front wheel gets misdirected. This is why many mtb'ers will run a faster tread on the rear and higher traction front tread.

Deeper rims also tend to be stronger/more durable and since the rear wheel gets more abuse than the front, there's that benefit as well. I know some sprinters that like a deep rear wheel for that fact. I'm not sure how much this matter as most carbon wheels are pretty stiff if they have a reasonable number of spokes.


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## froze (Sep 15, 2002)

I don't race so all this is really IS NOT (edit, key words left out) important to me personally, but I find when I see people riding with deep dish rims that it looks ugly to see two different rim profiles on a bike, but that's just in the looks department. If I was racing I would probably settle for a compromise with a 50mm instead of a 60 on the front and a 30 on the rear. It the rim profile is built rounded instead of V shaped at the top where the spokes come out the cross wind factor is severely reduced according to what I've read.

Zip has a PDF on this rounded vs V business, see:www.zipp.com/_media/pdfs/technology/rimshape.pdf


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## TricrossRich (Mar 26, 2014)

SwiftSolo said:


> You are correct. On the other hand, I doubt the op was confused by my last sentence referring to the impact of cross wind on a narrower (profile) rim--especially in view of the first sentence.





froze said:


> I don't race so all this is really important to me personally, but I find when I see people riding with deep dish rims that it looks ugly to see two different rim profiles on a bike, but that's just in the looks department. If I was racing I would probably settle for a compromise with a 50mm instead of a 60 on the front and a 30 on the rear. It the rim profile is built rounded instead of V shaped at the top where the spokes come out the cross wind factor is severely reduced according to what I've read.
> 
> Zip has a PDF on this rounded vs V business, see:www.zipp.com/_media/pdfs/technology/rimshape.pdf


Yes, totally understand the effects of shape on aerodynamics and the wheels I'll be running are rounded, not v shaped.


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## November Dave (Dec 7, 2011)

SwiftSolo said:


> I think the thing to remember is that wind tunnel testing on bikes is as much about marketing as it is about science. Testing aerodynamics of bikes or components without a rider on board pedaling is purely about marketing hype.


I understand your thinking on this, and there are cases where it may be true, but it's not even close to universally true. A rider introduces a lot of noise into the equation - while I rode in the wind tunnel as part of the above cited study, the error bars went from basically nothing for bike with no rider to quite significant for rider on bike. Which means that you'd have to run a serious number of tests to get meaningful data, which introduces a cost factor into it ($500+/hour just for the tunnel time, disregarding the other substantial costs of getting and being there) which would make such a study unfeasible. 

In the case of our test, it was purely a cost we bore to be able to give an informed answer to a significant question that a lot of people ask. Same as with the "how much do disc brakes slow you down" question - people can stand there and throw guesses at it for years and years, but until you know, you don't know. Now we know. 

Thank you


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## 4slomo (Feb 11, 2008)

ENVE sells their SES wheels which use a lower depth wider rim on the front and a greater depth narrower rim on the rear, based on their wind tunnel testing results.



TricrossRich said:


> I'm currently running 50mm deep wheels on my Venge. I am about to start building up an Allez to use for crit racing and at first I was going to buy 60mm wheels, but then last night I realized i could get a 38mm front and 60mm back.. I would then run the 50 front/ 60 rear on the Venge and the 38 front/50 rear on the Allez. Is there any advantage to doing something like this? Do people do this? Several friends of mine have both Zipp 303's and 404's and occasionally they run a 303 front, 404 rear and call it a 304.
> 
> The only obvious advantages I can see is that running a smaller front would save some weight, compared to a front of the same depth as the rear. It would also be less susceptible to wind gusts. The downside being that the front wheel is slightly less aerodynamic. Any effects on handling I should be aware of? Thoughts.


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## SwiftSolo (Jun 7, 2008)

I agree that anyone looking for a fast riderless bike should be interested in riderless bike wind tunnel testing. Those looking for a fast bike with a pedaling rider on board should pretty much disregard that testing. 

Prior to 2000, countless wind tunnel test were completed to determine the fastest (least drag) masts for high performance sailboat racing. The masts were tested without sails /sailcloth since that material was downwind and thought to be substantially irrelevant.

Testing for the 2000 A/C found that previous assumption to be simply wrong and that sections showing minimal drag (all known previous testing) using that metric were far from the fastest in the real world. 

The point is that reducing the drag of a riderless bike does not equate to reducing the drag of a bike with a rider. In some instances, the two can be inversely related.


November Dave said:


> I understand your thinking on this, and there are cases where it may be true, but it's not even close to universally true. A rider introduces a lot of noise into the equation - while I rode in the wind tunnel as part of the above cited study, the error bars went from basically nothing for bike with no rider to quite significant for rider on bike. Which means that you'd have to run a serious number of tests to get meaningful data, which introduces a cost factor into it ($500+/hour just for the tunnel time, disregarding the other substantial costs of getting and being there) which would make such a study unfeasible.
> 
> In the case of our test, it was purely a cost we bore to be able to give an informed answer to a significant question that a lot of people ask. Same as with the "how much do disc brakes slow you down" question - people can stand there and throw guesses at it for years and years, but until you know, you don't know. Now we know.
> 
> Thank you


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## November Dave (Dec 7, 2011)

I wondered if your screen name was related to the boat. I'm a fairly experienced sailor - won't bore you with credentials but I know some of the people who would have done a lot of the testing you reference. 

Unlike in the mast without sail/with sail testing, wheel performance alone -> in a bike with no rider -> in a bike with rider have proven to be closely related. People who've tested themselves with one rear wheel versus a disc, say, have shown testing similarities to what we've gotten. 

The bigger point I was addressing, however, was the dismissal of our effort as "marketing hype." What dog have we got in the fight? You spoke as though we had some ulterior motive. Would you rather we had not tested and just thrown out an opinion, as is too often done? I have a lot of trouble understanding that accusation.

If you feel that our results inaccurately represent the actual truth, it would be easy enough to test that hypothesis. It just takes money. Our investment was in getting a good answer, which we think we've done.


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## SwiftSolo (Jun 7, 2008)

My apologies. My comments were not intended to be directed at you but rather at the idea of basing purchasing decisions on wind tunnel testing of riderless bikes and components.


November Dave said:


> I wondered if your screen name was related to the boat. I'm a fairly experienced sailor - won't bore you with credentials but I know some of the people who would have done a lot of the testing you reference.
> 
> Unlike in the mast without sail/with sail testing, wheel performance alone -> in a bike with no rider -> in a bike with rider have proven to be closely related. People who've tested themselves with one rear wheel versus a disc, say, have shown testing similarities to what we've gotten.
> 
> ...


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## TricrossRich (Mar 26, 2014)

Hey guys... thank you all for chiming in and giving advice and pieces of information to look at. I researched here, as well as some other places, including internet searches and contacting some other people in the bike industry. One of the places I contacted was SBCU, Specialized Bicycle Components University.... They're the guys at Specialized that do the win tunnel videos. Mark Cote, head of Aero R&D at Specialized contacted me and he said:

"from our testing in the Win Tunnel, 60/60 or 40/40 works very well for their specific pruposes. 

In a low crosswind scenario, like the crit you're mentioning, the 60 rear will not benefit you aerodynamically. And similarly when others have run deeper rear wheels than front, they'd have to go a bit deeper to get any benefit - otherwise it's just fashion.

Actually, while it'd look a bit weird, it'd make more sense to go deeper on the front - clean, faster air hitting the front of the bike and the 60 is more aero than the 40. Run the 40 in the rear and you have less rotational inertia so you'd be able to accelerate out of corners better. 

If you want the real speed setup and are open to looking different, run a CLX40 rear with a Turbo 26 and a CLX60 front with a Turbo 24. The larger rear tire helps with traction, lower rolling resistance and there's no aero loss. The front tire matters for both rolling and aero, so it needs to be a bit narrower than the rear.

When I did the math, it turned out that running the 38/50 combo would save me about 40G over a straight 50/50 combo. When I told Mark this, his response was.

"I don't have data to back this up, but on the scale we're talking about aero is likely > rotating mass on the order of 75g"

I ultimately decided to go with a straight matched set of 50mm wheels.


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## froze (Sep 15, 2002)

^^ This agrees with what I said earlier and that was to put a more aero rim on the front and a less aero one on the rear. 

I looked into all of this a while back and decided when I get another set of wheels was to get 50 on the front and either buy another 30 or leave the 30 I have on the rear, being a tightwad I'll probably leave the 30 on the rear...BUT then again I will probably buy another wheel since they won't match.


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## November Dave (Dec 7, 2011)

The info from Specialized seems to match ours nearly exactly, which isn't at all surprising.


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## Keoki (Feb 13, 2012)

TricrossRich said:


> Hey guys... thank you all for chiming in and giving advice and pieces of information to look at. I researched here, as well as some other places, including internet searches and contacting some other people in the bike industry. One of the places I contacted was SBCU, Specialized Bicycle Components University.... They're the guys at Specialized that do the win tunnel videos. Mark Cote, head of Aero R&D at Specialized contacted me and he said:
> 
> "from our testing in the Win Tunnel, 60/60 or 40/40 works very well for their specific pruposes.
> 
> ...


I called Zipp and asked the same question couple years ago and their response was exactly the same as Mark's.


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## thalo (Jul 17, 2011)

there was a guy that won a crit race a few weeks back with about a 85mm front and 35mm rear set up. won by about 300-450m (not good with judging distances like that). So, yes some do.


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## fedrusion (Jul 26, 2010)

This sounds like about how my bike/bikes look. I have a set of 38mm tubs and 50mm tubs. Its hit or miss what my combo looks like mostly driven by what front/rear is in the best shape for racing and if there is even a tire glued onto a specific wheel. Usually I will try to run a matched pair if I have the option. Though one of my best races was with a 50 up front and a loaner shallow section clincher in the rear after flatting just before the start of a race.


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