Deep dish rims-do they really make a difference?

Schneiderguy · Aug 30, 2007

I have Rolf Vigor wheels- 34 mm, factory claim weight of 1470 gr, & low spoke count. I think these are about as good, in terms of performance, as I will find in terms of aero, weight for an traditional clincher rim. Disclaimer: I'm not saying these are "better" wheels than some other brand or make.

The deep dish lust has struck. I do a few road races, a few ralley rides as though they were races and fast race team training rides several times a week. I'm no longer serious about racing, but like to hang with good riders as long as I can. The routes are flat to rolling. A typical Saturday 55 mile ride in the "hills" will have 1800-2400 ft of climbing. Nothing really long or steep. When riding in excess of 20 mph (last Thursday I lost a lung going 35.5 on the flats with no significant tail wind that I was aware of) would 50 mm CF rims make any noticeable difference in performance over the Rolfs? I guess I'm asking would I be able to ride the same speed (20+) and produce less watts at a leve I would be aware of? The wheels I'm thinking about are inexpensive (thanks to our friends in the far east) CF clinchers without Al braking rim and weigh 1630 grams.

Mark McM · Aug 30, 2007

Deep wheel advantage

Before I answer the question, a quick rant -

There is no such thing as a "deep dish" wheel! The dish of a wheel is due to the aligning the rim off-center from the flanges on a rear wheel (to correct the assymmetry of the flanges due to making room for the cassette on the drive side)! A "deep dish" is a style of pie, not a wheel!

Your question really has two parts:

Q: Will deep rims make a difference?
A: Yes, deep rims can decrease drag, slightly increasing speed a given power, or reducing power at a given speed.

Q: Will the difference be noticeable?
A: Probably not. Speed increases/power reduction is quite small, so if often requires a stop watch to actually measure the difference. Compared a traditional wheel with a shallow rim and 32 spokes, the very best aerowheels will increase speed/reduce power by only a few percent. Given all the other variables involved in cycling (terrain, wind, pavement condition, or just how the rider is feeling that day) the improvements with the aerowheels can get lost in the noise.

You're Rolf Vigor wheels already have a fairly deep rim and a reduced number of spokes, so going to any even more aerodynamic wheel is likely to result in an even smaller, less noticeable difference.

If you want to ride faster (or ride at the same speed with less effort), a more cost effective way (i.e. more improvement per dollar) is to hire a coach to maximize the performance of your engine.

kyler2001 · Aug 30, 2007

Mark McM said:
If you want to ride faster (or ride at the same speed with less effort), a more cost effective way (i.e. more improvement per dollar) is to hire a coach to maximize the performance of your engine.

Well said...:thumbsup:

Schneiderguy · Aug 31, 2007

thanks. That's what I suspected. But I would look so much faster

Think I'll save the money and train harder.

Dizzy812 · Aug 31, 2007

Of course the 'just get fitter/lighter' advice is valid.

However, this assumes riders are completely insensitive to technological improvement.

Your max speed will increase. Your average speed will increase. You may set a new speedrecord on your favorite 'rollout'. Certainly you'll be thrilled with improved acceleration at higher speeds.

Areo rules and so does speed you can buy.

rger8 · Sep 4, 2007

Don't kid yourself, looking fast is a great mental upper!

( I have a great imagination! ) I just got my new Easton Vista SL Aero's and I feel way faster, although I'm probably not!

Did notice side wind effects though, not so good. I can really feel the wind push the rim. Really, it was a great upgrade from what I had and glad I spent the money. I noticed the smoothness of the hub more than anything. Upgraded from Alex 290 wheels.

Pablo · Sep 4, 2007

rger8 said:
Don't kid yourself, looking fast is a great mental upper! ( I have a great imagination! )

It sort of cuts both ways. Few things make you feel like more of a bad-a$$ than passing someone on a bike that's nicer than yours.

I am skeptical of the physical advantages of big rims. However, nice wheels with quality hubs and bearings are significant.

asgelle · Sep 4, 2007

Pablo said:
I am skeptical of the physical advantages of big rims.

What are your feelings on this gravity thing?

den bakker · Sep 4, 2007

asgelle said:
What are your feelings on this gravity thing?

It's a downer

Pablo · Sep 4, 2007

asgelle said:
What are your feelings on this gravity thing?

I understand that big ol' rims and high tech wheels offer advantages, e.g. rotational weight blah, blah. However, I am skeptical about the significance of such advantages.

asgelle · Sep 4, 2007

Pablo said:
I understand that big ol' rims and high tech wheels offer advantages, e.g. rotational weight blah, blah. However, I am skeptical about the SIGNIFICANCE of such advantages.

Really?

Pablo said:
I am skeptical of the PHYSICAL advantages of big rims.

Pablo · Sep 4, 2007

Geez, what is this, cross examination? I'm skeptical about the significance of the physical advantages of these rims. I used the word "physical" to distinguish from the mental and psycological benefits discussed by rger8 in post #6. What can I say, I'm a skeptical guy.

den bakker · Sep 4, 2007

Pablo said:
Geez, what is this, cross examination? I'm skeptical about the significance of the physical advantages of these rims. I used the word "physical" to distinguish from the mental and psycological benefits discussed by rger8 in post #6. What can I say, I'm a skeptical guy.

well, as long as we don't know what you mean by significant, the discussion is kinda moot.

Pablo · Sep 4, 2007

den bakker said:
well, as long as we don't know what you mean by significant, the discussion is kinda moot.

It seems like for the vast majority of riders, including most competitive riders and racers, the advantage gained in speed from deep rims is minimal. This advantage seems very small and thereby would seem to be an insignificant factor in how fast a bike can be ridden and in accompanying competitive results.

From what I understand, and my understanding is certainly not perfect in this area, deep rims decrease air restsience and rotational weight to a rather small degree that translates into very little extra velocity resulting from the different rim. So, it seems like if you had two riders, assuming all other things equal, which of course would never happen in real life, the guy with deep rims would only go a touch faster. In reality, it seems like you could make up this slight loss in speed through other means.

Further, at least to me, and I understand that everyone has difference economic means and would do their own cost-benefit calculation, this benefit seems minor compared to the additional monetary cost.

Of course, it's all subjective: my insignificance is others' significance.

I guess that's sort of what I mean by "significant" in this context.

TurboTurtle · Sep 4, 2007

den bakker said:
well, as long as we don't know what you mean by significant, the discussion is kinda moot.

Well, what I would mean as significant in (agreement with Pablo) is that the riders that drop me now would still drop me no matter what wheels I'm riding. - TF

den bakker · Sep 4, 2007

TurboTurtle said:
Well, what I would mean as significant in (agreement with Pablo) is that the riders that drop me now would still drop me no matter what wheels I'm riding. - TF

well, the same is true no matter what hub or bearing you used but Pablo claims that is an important factor in a wheelset.

Pablo · Sep 4, 2007

I was always under the impression that bearings make a bigger difference than rims. I may be wrong.

den bakker · Sep 4, 2007

Pablo said:
I was always under the impression that bearings make a bigger difference than rims. I may be wrong.

at around 15mph, wind resistance becomes the dominant source of resistance.

Pablo · Sep 4, 2007

But wouldn't bad bearings still slow you down no matter how fast you're going, like when you're going uphill, or in all conditions, like when there's a cross or tail wind?

den bakker · Sep 4, 2007

Pablo said:
But wouldn't bad bearings still slow you down no matter how fast you're going, like when you're going uphill, or in all conditions, like when there's a cross or tail wind?

yes but the term will still only be a linear fuction of speed, unlike drag which goes as the speed square.

Deep dish rims-do they really make a difference?

Schneiderguy

Mark McM

kyler2001

Schneiderguy

Dizzy812

rger8

Pablo

asgelle

den bakker

Pablo

asgelle

Pablo

den bakker

Pablo

TurboTurtle

den bakker

Pablo

den bakker

Pablo

den bakker

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