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  1. #1
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    wide rims: hype or improvement?

    Are wide rims just a bunch of hype, or do they make for more aero wheels and/or less rolling resistance?

    Are the benefits the same with tubulars vs clinchers?

  2. #2
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    No hype, IMHO. At least with regard to ride and handling improvement.

    I don't own a wind tunnel so I can't speak to the aero. Same with the rolling resistance. AndI only run clinchers.

    But I've switched to wider rims on two of my bikes (so far). Using the very same tires, just moving them from 19mm rims to 23mm rims, on both bikes I immediately felt an improvement in ride. Handling improvement is subtle, but it's there. It's hard to articulate the difference in the feel, but it's very nice and confidence-inspiring.

  3. #3
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    At first, I will admit that I was a skeptic of hopping on the hype train for wide rims. It didn't seem like it would make that big of a difference to me. However, after talking to a few of our customers who had them, I started to second guess myself. So eventually I decided to hop on a pair to see what all the fuss was about.
    Now, I will admit that in a straight line, wide rims feel almost exactly the same as any narrow rim. However, where I noticed a considerable difference was in the cornering. When leaning the bike over, a wider rim really does feel more consistent, predictable, and stable than some of the < 20mm wide counterparts.
    All in all, I would say absolutely go for a wider rim. The clinchular style really does have the ride quality of tubys, with the convenience of a clincher.

  4. #4
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    I haven't noticed any significant difference in rolling resistance or aero improvements at high speed or when it's windy. There aren't too many places for me to test high speed cornering where I ride (damn stop signs) but I think I am a little more confident leaning the bike over farther and cornering at higher speed. The main benefit for me is ride quality on rough pavement and the ability to run lower tire pressure. I can easily run 80 psi without excessive tire sidewall bulge and no pinch flats. I'm happy to move away from the jarring ride of 100psi and narrow rims or the bouncier and more isolated feel of wider tires.

  5. #5
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    Switched to Hed Ardennes rims and love the feel of the wider rim. It definitely has a more composed ride. I have a number of sets of very nice wheels that I bought before I built up the Hed rims, and I will occasionally put a set of them on to ride for a week or so. I am always suprised at the difference when I go back to the Hed rims. It is a noticeable improvement.
    As far as the aero advantage, I have seen testing results that show an advantage. My thoughts are that in aeronautics when the airplane speed is lower a thicker wing is more efficient. That is the reason that planes use slats(front of the wing) and flaps(rear of the wing) to alter the shape of the wing when landing and taking off.
    The rolling resistance test that convinced me was Continental in Germany. I don't remember if it was Hed or Stans that sent them their wider rims and asked them to test rolling resistance with Continental tires. The engineers did not expect to see a measureable difference, but their was noticeably less rolling resistance with the wider rim.

  6. #6
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    I don't know nuthin' from nuthin' on these, as I don't yet have a pair - but looking to build some up soon. I did want to make a note about the aero theory about these:

    The key thing: They aren't significantly wider then a standard set, as a wheel-tire unit. What they are is smoother: Rather than shaping like a lightbulb, the rim becomes tangent (or nearly so) to the widest part of the tire. In theory, that lets the air flow over the tire and rim more smoothly.

    That's likely a fairly small point on low profile rims like the Belgiums or A23s, which aren't very aero anyway. Not much sense in bothering to avoid the separation that's going to occur quickly enough anyway. It probably has some benefit, but I won't speculate how much or at which angles, etc. For deeper rims like Jets, it's relatively more impactful, since they do have a better opportunity to keep the airflow together.
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  7. #7
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    I had some wheels built for my commuter/touring bike with Velocity Dyad rims, which are the same width as A23s. I noticed no improvement in ride quality, handling or aerodynamics but this bike is used primarily for commuting with a large seat bag.

    The Dyads are heavier than A23s and mine have 36 spokes, so they are noticeably heavier than my other wheels, which all have Open Pros. I recently bought another set of Open Pros to put back on my commuter bike because the extra weight was not worth any perceived benefit from the Dyads. The biggest disadvantage to the Dyads (or A23s) is that you can't simply swap wheels with other road bikes unless they also have wider rims because the brakes will be out of adjustment. The first time I swapped wheels I forgot this simple fact and almost killed myself. Headed down my driveway (which is on a hill), reached for my brakes to slow down at the street, and my bike kept going like I had no brakes at all. Fortunately there wasn't a car coming or I would have been run over.

  8. #8
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    I don't notice any difference in aero or rolling resistance.
    Not that I think I would be able to accurately detect any aero or rolling resistance difference even if it was there.

  9. #9
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    How much wider do these rims make the wheel (tire) at it's widest point? With 20mm Mavic rims and 25mm Krylions, I only have about 1/16" clearance at the left chain stay on my Felt Z. I am considering A23s (with 25mm tires), but fear they would rub.
    Joe
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  10. #10
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    Quote Originally Posted by ericm979 View Post
    Are wide rims just a bunch of hype, or do they make for more aero wheels and/or less rolling resistance?
    Nothing wrong with them. There is no rolling resistance benefit (measured) and no aero benefit unless it is a deep+wide rim. I think the handling thing is placebo. How many people test their cornering limits on a regular basis? I haven't noticed that a high pressure tire on a narrow rim suffers from handling issues.

    Plus... if matching the tire and rim width is so magical, then you should feel the same magic by putting 20mm tires on your 20mm rims...

  11. #11
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    i politely disagree.

    have ridden mtb tubeless, low pressure, wider rims and obviously the results speak for themselves at the international level; anyone who wants to be even remotely competitive is on to this idea.

    now, roadies are very traditional and slow to change, but things are all slowly moving in that direction with data to back up the ideas.

    Zipp, HED and others are moving to wider rims which change the profile of the tire on the rim from a narrow one.

    one benefit is going to be traction, and how the tires follows the terrain instead of moving in the vertical plane.
    this means better handling, don't know about you but on a steep descents with many turns I would take the widest tire i could find and disc brakes and say see you at the bottom, while others hold on for dear life to their skinny and marginal grip on their existence..lol

    now aero, dont know, but unless riding in tt who cares...
    Last edited by a_avery007; 09-09-2011 at 05:05 PM.

  12. #12
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    Quote Originally Posted by a_avery007 View Post
    have ridden mtb tubesless, low pressure, wider rims and obviously the results speak for themselves at the international level; anyone who wants to be even remotely competitive is on to this idea.
    There is no comparison. On an MTB, you are on a soft and rough surface... where fat tires, low pressure, pinch flat resistance... and a wide rim to accommodate the low pressure... make sense. Besides that, the tire is still *much* wider than the rim.

    Road bikes have a completely different set of requirements.

  13. #13
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    I think it is a marketing gimick to sell wheelsets that cost more.
    Both A23 and C2 rims are significantly more expensive than conventional rims.
    Just thinking about it, for a given tire size a wider rim would LOWER the tire profile possibly resulting in more pinch flats and a rougher ride. Might make some sense with 25mm tires but certainly not 23mm

  14. #14
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    I switched and ride HED Ardennes as well as A23s (laced to White Indust hubs). Definitely better cornering and handling over rough roads due to wider profile and lower tire pressure. The HED C2 rims are bit expensive but the Velocity A23s are less expensive than a Mavic Open Pro.
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  15. #15
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    With clinchers I do like the Ardennes as it allows the tire to be a bit rounder, and more tubular like in handling and feel. Not a huge difference, but noticeable. As far as aero I switched from the old 404's, to the FC's (both tubular) mid season, and there was no real change in speed at a given power on my usual training route. Not really scientific, but I can neither feel any difference, nor detect it with my power meter in terms of forward speed. I touch more stable in sidewinds maybe, but I'm used to riding with deep wheels so it's never been something I've paid attention to anyways.

  16. #16
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    where I live and ride all those characteristics still apply to road bikes.

    yes, i ride on road tubeless too for those exact same reasons.

    this trend is not going away anytime soon and will only expand further into the road market.

    whether you want to have a better riding experience is up to you, i prefer safer, faster and more comfortable all in a single riding experience.

  17. #17
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    Quote Originally Posted by jnbrown View Post
    I think it is a marketing gimick to sell wheelsets that cost more.
    Both A23 and C2 rims are significantly more expensive than conventional rims.
    Just thinking about it, for a given tire size a wider rim would LOWER the tire profile possibly resulting in more pinch flats and a rougher ride. Might make some sense with 25mm tires but certainly not 23mm
    I have to disagree. You can get A23s for as little as $53.00. While It is counterintuitive, the profile is not lowered (at least not by any appreciable amount) and the greater volume provided by the wider rim protects from pinch flats even at reduced pressures. While some of the benefits may be overstated, there is no question that wider rims improve the quality of the ride.

  18. #18
    Fuel-sippin' fool
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    Quote Originally Posted by jnbrown View Post
    Just thinking about it, for a given tire size a wider rim would LOWER the tire profile possibly resulting in more pinch flats and a rougher ride...
    Sorry, but you're wrong across the board in your assumptions.
    1) the tire build height would only decrease by a meaningful measure if the tire were already spread out to the full width of the rim (picture a low-profile car tire), and they you put them on an even wider rim. You can stretch out the bottom edges of the "light bulb" profile of a mounted, 23mm tire from 14mm to 18mm (the inner dimensions of 19mm & 23mm rims) without perceptibly changing the build height.
    2) The geometry is pretty simple: you've got a larger overall cross-section and thus more air volume inside the larger combined chamber formed by the wider rim/tire unit. That greater volume of air = greater cushion to absorb hits, which is why you can drop pressure.
    3) to get a pinch-flat, the tire has to bulge out over the outer edge of the rim wall. The less it does this, the less there is to pinch in the case of a big hit. Remove the tube from the wide-rim equation (tubeless anyone?) and your chance of pinch flatting goes from lower to zero ...

    I'm as suspicious of industry hype as the next guy, but the move to wide rims makes a lot of sense.
    I'd really love to see some quantitative data on "ride quality," but rather than waiting around for that, I'm going to go out and replace the 19mm Velocity rims I just cracked on our crappy, potholed, chipsealed local roads with something nice & fat, and go out & do some field testing myself.
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  19. #19
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    Quote Originally Posted by BergMann View Post
    You can stretch out the bottom edges of the "light bulb" profile of a mounted, 23mm tire from 14mm to 18mm (the inner dimensions of 19mm & 23mm rims) without perceptibly changing the build height.
    That greater volume of air = greater cushion to absorb hits, which is why you can drop pressure.
    However imperceptible that height difference is, the volume difference will be even less. Just run a 25mm tire and you've increased volume a lot more than if you switched to a wide rim.

    to get a pinch-flat, the tire has to bulge out over the outer edge of the rim wall. The less it does this, the less there is to pinch in the case of a big hit.
    It doesn't matter how *much* tire is bulging out... only *if* it does... and they all do. If the tire sidewall gets pinched between the rim and the ground, then the tube will also.

  20. #20
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    I wonder why anyone would argue against it. Rims got narrower before because tires got narrower. Now that we know ultra narrow tires don't benefit a road bike ride, wider tires are getting common. It only makes sense to have rims to match. You also get more air volume inside the tire, which will allow it to conform better to the road surface and add additional cushioning to the ride. Some may easily notice the difference, while others may not. But, the benefit will definitely be there.
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  21. #21
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    [QUOTE=roadriderR5;3544754] My thoughts are that in aeronautics when the airplane speed is lower a thicker wing is more efficient. That is the reason that planes use slats(front of the wing) and flaps(rear of the wing) to alter the shape of the wing when landing and taking off.
    [QUOTE]

    I am not sure that correlates to lower wind drag that is desired in a bicycle wheel. The point of an airplane wing is not to minimize drag, but to create a pressure differential on one side of the wing vs the other, aka lift. The slats and flaps help alter the wing's lift characteristics, but do not reduce drag. (which is what you desire in a bicycle wheel). Reducing frontal area and turbulence are two of the big factors in making vehicles "aerodynamically efficient".

  22. #22
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    Quote Originally Posted by dakota View Post
    I have to disagree. You can get A23s for as little as $53.00. While It is counterintuitive, the profile is not lowered (at least not by any appreciable amount) and the greater volume provided by the wider rim protects from pinch flats even at reduced pressures. While some of the benefits may be overstated, there is no question that wider rims improve the quality of the ride.
    Correct, a bicycle tire cross section, with the rim is bascially round. By adding rim width, you are increasing the circumference and thus the diameter (both vertically and horizontally. Now if you go way overboard and put such a wide rim on that you create an oval, you have another story.

    Many people have more experience with car tires. When thinking of a car tire, the tire can be thought of as much more of a rectangular section with a flat tread and vertical sidewalls (yes, they buldge). In that case when the rim is wider than the tread, you turn the rectangle in to a trapizoid and he profile height indeed becomes lower. Again, that holds true more for a car, not a bike.

  23. #23
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    Quote Originally Posted by rruff View Post
    However imperceptible that height difference is, the volume difference will be even less. Just run a 25mm tire and you've increased volume a lot more than if you switched to a wide rim.
    It doesn't matter how *much* tire is bulging out... only *if* it does... and they all do. If the tire sidewall gets pinched between the rim and the ground, then the tube will also.
    Glad to hear you're jumping on the increased volume bandwagon. Heck, we could run 32mm cross tires and have even more.

    You're still missing a central point here: key to not just the aerodynamic, but also cornering & flat-resistance principle is replacing the "light bulb" profile of a 23mm tire on a 19mm rim with something that looks more like the U profile of a car tire.

    The "light bulb" profile leads to tire flop in corners, period. You can get a tire with a stiffer casing to reduce this flop, or you can widen the rim.
    As for pinch flats, same story: running higher pressure and/or having a stiffer sidewall better resists tire compression.
    Widening the rim to allow sidewalls to run closer to perpendicular would add yet further structural resistance to compression. The amount of bulge *does* matter - not so much for whether there will be some overlapping tube to pinch (there will), but because a perpendicular sidewall section is going to resist compression better than a curved sidewall section.

    What I don't get about some of the retro-grouching against the industry shift to wider rims, is why argue against technology that optimizes the performance of the 23mm, 200-220g clinchers most road riders are already riding?
    I get grouchy too whenever I smell the industry trying to sell yet more useless BS (integrated bar/stem combos anyone?), but tire technology has been improving in leaps & bounds in recent years, and as a rider who has been at this sport for almost 3 decades now, for the first time, I'm starting to get the sense that recent developments in wheel technology are finally starting to be relevant to someone other than Fabian Cancellara.
    If replacing my recently-deceased 19mm wheelset with a 21-23mm wide rim will make my amazing 23mm Conti 4000s perform even better while cornering, then frankly, I don't care whether or not there are added aero, rolling resistance, or flat-resistance benefits.

    Besides, be honest now, when was the last time you had a pinch flat on a properly-inflated 23mm road tire? I ride on *abysmal* road surfaces at irresponsible speeds, and run 105psi front, 110psi rear, and haven't pinch flatted in at least a decade.
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  24. #24
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    Quote Originally Posted by joe4702 View Post
    How much wider do these rims make the wheel (tire) at it's widest point? With 20mm Mavic rims and 25mm Krylions, I only have about 1/16" clearance at the left chain stay on my Felt Z. I am considering A23s (with 25mm tires), but fear they would rub.
    The Michelins (Krylion,Pro2Race, and some Pro3Race, Optimum Pro) in size 700x25c have always been 27mm wide and 26mm tall; at least on a rim of 15mm inner width (e.g Mavic Equipe, Fulcrum Racing 5).

    A Michelin Krylion in size 700x23c has always been (width x height) 24.5mm x 23mm.

    Since they shifted production to the Far East tyres in size 700x23c run more to spec now. I fitted a brand new pair of Michelin Krylion Carbons and they are way smaller than all the Krylions I had in the past.

    The new bead-to-bead measure is only 60mm. All my other Krylions had 65mm. However, I am not sure if it stretches to 65mm after a few rides.

    By comparison a Vittoria Open Pave in size 700x24c has a bead-to-bead size of 65mm (as large as the older Michelins 700x23c).

    A 700x25c Michelin always measured 70mm bead-to-bead (e.g Krylion 700x25c).

    The new Michelin series Pro4Race (there will be 4 versions re-branding and replacing the Krylion, Pro3Race, Pro3Grip and Pro3 Light under the same main name) will also run to spec, so I have been told by Michelin UK custommer service. Although they said the 25mm will always run much larger. The German Tour magazine tested the Pro4Race Light 700x23c and it only measured 22mm wide and 21mm tall.

    Why not just fit a 23mm Michelin if you have got problems with tyre clearance?

  25. #25
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    Quote Originally Posted by BergMann View Post
    The "light bulb" profile leads to tire flop in corners, period. You can get a tire with a stiffer casing to reduce this flop, or you can widen the rim.
    Anybody who regularly races down switchback descents (like I do) would know about this. My narrow rims do not result in any "tire flop" that I notice. A narrow high-pressure bicycle tire just doesn't have a lot of room to flop around. A 50+mm MTB tire inflated to 25 psi with a 22mm rim... sure, I bet you could feel a difference going to a 28mm rim. Totally different story. But note that the rim is still way narrower than the tire.

    As for pinch flats, same story: running higher pressure and/or having a stiffer sidewall better resists tire compression. Widening the rim to allow sidewalls to run closer to perpendicular would add yet further structural resistance to compression.
    If they have higher resistance to compression, then they *must* have less compliance. You can't have it both ways, but the manufacturers claim you do.

    What I don't get about some of the retro-grouching against the industry shift to wider rims, is why argue against technology that optimizes the performance of the 23mm, 200-220g clinchers most road riders are already riding?
    What I don't like about it, is that it's 99% marketing BS... plain and simple. Bill Hicks on Marketing - YouTube

    A wider rim isn't going to particularly *hurt* anything (weight being the only clear negative), and frankly I think 21mm is the sweet spot for 23mm tires. But it isn't going to make a beneficial difference either, to ride comfort or aerodynamics or handling that anyone can notice... except that bicycle stuff is so placebo and belief driven that everyone claims they notice it! We had ceramic bearings that were hyped to result in big speed increases, and now this... "lower resistance, more compliant, fewer pinch flats, more aerodynamic, better handling". Wow... sounds awesome! Unfortunately the only one that passes examination is the aero one... *if* it is a deep rim with a 23mm tire. And that isn't what we are talking about here.

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