Wide rims versus wide tires?

[mhespenheide]

Forgive me if this has been discussed before -- if so, can you point me towards the appropriate thread(s)?

Has anyone ridden an A/B comparison of similar width comparisons between different sizes of tires and rims that ended up having the same final width? I'm wondering about something like comparing a 25mm tire on a wide rim versus the same tire in 28mm on a standard rim. To put it another way, is there something more to the ride of a wide rim than just the additional width of tire that it provides?

Second question: if there really is a benefit to the wide rim (beyond the extra width of the tire), as is talked about with the "bread-loaf" shape better than the "light-bulb" shape, do those benefits go away if a wide tire is used? Say, a 28mm (nominal) tire on a wide rim -- doesn't that get back to a "light-bulb" shape? If those benefits do go away, should we be looking at even wider rims? Should we be lacing up some 29'er rims for the road to go with 28mm or 30-35mm tires?

Thanks for any thoughts/input -- particularly on that hypothetical A/B comparison.

[Bruce K]

Some manufacturers already make 25mm rims (HED Plus).

Yes a 28 tire on a 23 rim just makes a larger "old" profile

BK

[Ralph]

Not everyone (me included) buys into the lastest fad of wide tires on wide rims. Especially for all uses, all riders, all body weights, all roads, etc. Agree the tire needs to fit the rim properly, and there are plenty of good uses for a wider tire. I even use a 700X25 on my daily rider. But my fastest wheels overall still have 700X23's. I might add I only weigh 155 and I ride on smooth roads.

[tigoat]

I have used ENVE 45 (traditional narrow rims) rims with 28c tires and ENVE 29XC rims (modern wider rims) with 25c tires. They do not feel the same way. The ENVE 29XC wheels feel much more smoother and faster and resemble more of a tubular feel. I have also used HED C2+ rims, which are probably widest road rims available right now. The HED C2+ wheels perform very similarly to the ENVE 29XC wheels. Bottom line is that don't fool yourself into slapping on some traditional narrow rims with wider tires and think they perform the same as modern wider rims do, as they are not the same.

[Mark McM]

I would expect that it to be not unlike comparing different profile automobile tires. On the one hand,a bigger tire (both wider and taller) will give a more compliant ride, at the cost of some lateral stability. On the other hand, lowering the profile (shorter sidewall height) for a given tire width will be less compliant, both vertically and horizontally. If this works the same on bicycle tires, than mounting a fat tire on a narrow rim (lightbulb shape) will provide much more vertical compliance, at the cost of less lateral stability. Widening the rim, but keeping the tire width the same (bread loaf shape), will improve lateral stability at the cost of some of the veritcal compliance - but it will still have more vertical compliance than the narrower tire.

[Charles M]

there's a formula for net tire size... It's a mix and match thing and it's just math... I think wheelfanatyk.com have a little measuring device.

[mhespenheide]

I have used ENVE 45 (traditional narrow rims) rims with 28c tires and ENVE 29XC rims (modern wider rims) with 25c tires. They do not feel the same way. The ENVE 29XC wheels feel much more smoother and faster and resemble more of a tubular feel.

Thanks for that, tigoat. Guess I'll have to at least sip some of the kool-aid and try out some wide rims... My budget may have to wait until more people are selling them used, but I guess they're starting to show up.

[RobJ]

Tigoat and Mark McM nailed it and my testing combos falls in line with Tigoat. The ride quality of the wide/wide combo vs. narrow rim/wider tire is very noticeable. Running latex tubes has also contributed to a nice improvement. One other point not discussed, but important too is the aero properties of the various combinations. Most of the wider rims paired with a 23mm tire are topping the charts for aero and rolling resistance. Obviously mostly a concern if time trialing or triathlon etc.

[professerr]

***

[jamesutiopia]

Shifting from 23 to 25mm tires was a big improvement for me (190lbs, 63cm frame size). 28s have been even nicer, even on beautiful California roads. I've ridden 28s on Belgium+ rims, but not on narrow rims. They are nice for sure-footed descending.

I can see why this would be a less tangible benefit for more ideal-size riders.

[eippo1]

So to take this a bit further, I would like to fit a wider tire on my bike, but the limiter is the front brake having only 3mm clearance at the top with Conti 25's (that actually measure closer to a 28). If I went with a wider rim on this bike, would the tire, being less of a lightbulb, come down lower vertically since it is more spread out?

[zachateseveryth]

I would expect that it to be not unlike comparing different profile automobile tires. On the one hand,a bigger tire (both wider and taller) will give a more compliant ride, at the cost of some lateral stability. On the other hand, lowering the profile (shorter sidewall height) for a given tire width will be less compliant, both vertically and horizontally. If this works the same on bicycle tires, than mounting a fat tire on a narrow rim (lightbulb shape) will provide much more vertical compliance, at the cost of less lateral stability. Widening the rim, but keeping the tire width the same (bread loaf shape), will improve lateral stability at the cost of some of the veritcal compliance - but it will still have more vertical compliance than the narrower tire.

A wider rim will result in a better ride for any tire. You're increasing the air cavity volume so you can run a lower pressure without having to worry about pinch flats.

[druptight]

So to take this a bit further, I would like to fit a wider tire on my bike, but the limiter is the front brake having only 3mm clearance at the top with Conti 25's (that actually measure closer to a 28). If I went with a wider rim on this bike, would the tire, being less of a lightbulb, come down lower vertically since it is more spread out?

That depends. See the first post here: http://forums.mtbr.com/wheels-tires/tire-height-vs-rim-width-756818.html

[Mark McM]

A wider rim will result in a better ride for any tire. You're increasing the air cavity volume so you can run a lower pressure without having to worry about pinch flats.

The question wasn't about mounting the same tire on a wider rim, it was about comparing a wide tire on a narrow rim vs. a narrow tire on a wide rim (such that the final width was the same).

Also, air cavity volume by itself isn't what affects ride compliance (since there is virtually no compression of the air as the tire is loaded), but instead it is about the change in cross-sectional shape as the tire is compressed. For the same final tire width, the tire on the wider rim will actually be less compliant, since it takes less vertical compression to flatten the tire under load.

[ergott]

Not everyone (me included) buys into the lastest fad of wide tires on wide rims. Especially for all uses, all riders, all body weights, all roads, etc. Agree the tire needs to fit the rim properly, and there are plenty of good uses for a wider tire. I even use a 700X25 on my daily rider. But my fastest wheels overall still have 700X23's. I might add I only weigh 155 and I ride on smooth roads.

Seeing how you are from Florida I would agree. You won't see the same benefits that I do. Up here where the roads suck I love 23+mm rims and 28mm tires. I notice no loss of speed and my riding mates are jealous of how I glide over everything as they bounce around. I think slowly but surely I'm convincing some of them.

[marciero]

+1 on 28 tires. These seem to be sweet spot for me (160 lbs) for relatively nice roads. Currently with Open Pro rims, which are narrow. I also have Dyad (24mm) and Belgium+ (25 mm). Those are shod with 32 tires though. I have used 28's on the Dyads often enough but never really did an A/B with those (or the Belgium+) and the Open Pro and 28, and the difference did not jump out at me.

[gospastic]

I'm currently using some 32mm tires on standard rims - 19mm width or so. The difference is very pronounced when compared to the same tires on some 23mm width rims. Out of the saddle efforts feel weird. I can almost feel the tire folding over on itself. Cornering is also not as confidence inspiring.

[marciero]

My only caveat to that conclusion is that there are big differences in the construction of the Ardennes and C24s that, for all I know, might outweigh the differences in rim widths.


I think there may be something to the difference in construction of rims. The Belgium+ seemed to me to ride noticeably better than the Dyad, more than just the 1 mm difference would seem to explain. And I only had it in the front. But I could not say it wasn't all in my head. I experienced the same thing when I built up a 650b Pacenti SL 23 (24 mm) to replace the Velocity A23, again only on the front.

[Neil]

I'm a convert to the new generation of wider rims, coming from tubs.

I've got HED Belgium rims on the CSi with 25c Corsa's, it's hugely sure-footed and very comfortable.

I've got FLO30's with 25c Conti GP4000-S II's, same thing - and they alternate with 25c Ultremo's on HED Stinger 4's.

[nbl78s]

I was thinking of joining the wider movement but I am running Dura Ace 7700 (just because I just really love the looks of it). Will I run into fit issues using A23's and 25mm tires with the older 7700 brakes?

[Davist]

I went from 19mm to Archetypes, been using 28mm tires for years. To me, the difference was subtle, though definitely faster and more comfortable overall. Ran too low a pressure (oops! in the 60's at 190lbs) got some pinch flats until I figured out that ~85 front/90 back works for me. Side benefit is the width of the rims, I wanted to build my own wheels, lighter and better than factory wheels I could afford.

[Climb01742]

Seeing how you are from Florida I would agree. You won't see the same benefits that I do. Up here where the roads suck I love 23+mm rims and 28mm tires. I notice no loss of speed and my riding mates are jealous of how I glide over everything as they bounce around. I think slowly but surely I'm convincing some of them.

Eric, do you have a favorite 23+mm rim/28mm tire combo? Thanks!

[ergott]

Eric, do you have a favorite 23+mm rim/28mm tire combo? Thanks!

Hed and SL23 are both excellent rims. The SL23 does cost a little less and leaves nothing to want.

I have Hutchinson Secteurs set up tubeless on 2 different bikes. The ride is amazing especially on less than ideal roads. I'm only running 50-55lbs in them, no detectable loss in speed. I'd even take the bikes on fireroads and hard pack trails if the desire hits me.

Every time I'm out on my road bikes with bigger tires my desire for all the cool pro bikes fades and I realize my bikes are far better suited for what I do. I still have the Ottrott with skinnys to kick around on if need be.

http://ergottwheels.smugmug.com/Cycling/The-bikes/i-h8W44pk/0/XL/CoffeegrinderSpooky-1-XL.jpg

[oldpotatoe]

Hed and SL23 are both excellent rims. The SL23 does cost a little less and leaves nothing to want.

I have Hutchinson Secteurs set up tubeless on 2 different bikes. The ride is amazing especially on less than ideal roads. I'm only running 50-55lbs in them, no detectable loss in speed. I'd even take the bikes on fireroads and hard pack trails if the desire hits me.

Every time I'm out on my road bikes with bigger tires my desire for all the cool pro bikes fades and I realize my bikes are far better suited for what I do. I still have the Ottrott with skinnys to kick around on if need be.

http://ergottwheels.smugmug.com/Cycling/The-bikes/i-h8W44pk/0/XL/CoffeegrinderSpooky-1-XL.jpg

Wow, some truth there. I ride with 20mm rims, tubie one, DT585 other, 25c tires on my racer wanna be frames(MXLeader, Moots Vamoots) and I wish for nothing else, bike or wheel/tire-wise.

[Roadguy]

I would most likely train on tubulars if that was remotely practical for me but last year was my first year moving to a wide rim and I was sold purely on comfort. Rolling resistance, cornering etc. aside ... the jarring difference when running through holes in the rode was amazing comfort wise.

Nothing against my 19mm dura ace clinchers but they simply aren't nearly as comfy as my wide wheels.

[exapkib]

I was thinking of joining the wider movement but I am running Dura Ace 7700 (just because I just really love the looks of it). Will I run into fit issues using A23's and 25mm tires with the older 7700 brakes?

No troubles here. I've been riding a 7700 equipped bike with 25mm Conti 4000s on Pacenti SL23 rims for a while now without any trouble.

It does require some adjustment of the brake calipers, but I found that I have plenty of room to work with.

[nbl78s]

No troubles here. I've been riding a 7700 equipped bike with 25mm Conti 4000s on Pacenti SL23 rims for a while now without any trouble.

It does require some adjustment of the brake calipers, but I found that I have plenty of room to work with.

Thanks for the response... Much appreciated

[mhespenheide]

I've been out camping and away from the internet, but I just wanted to say thanks for the continued interest and contributions.

I'm in the midst of a long-term juggling of road bikes as I experiment with different options and toy with the idea of getting a custom frame. But one of the bikes I'm riding right now is a Lemond Poprad with wide rims and 28mm tires. It rides really nicely.

[dieonthishill]

I like wide rims and wide tires :) But then again, I am a MTBr...

[zachateseveryth]

The question wasn't about mounting the same tire on a wider rim, it was about comparing a wide tire on a narrow rim vs. a narrow tire on a wide rim (such that the final width was the same).

Also, air cavity volume by itself isn't what affects ride compliance (since there is virtually no compression of the air as the tire is loaded), but instead it is about the change in cross-sectional shape as the tire is compressed. For the same final tire width, the tire on the wider rim will actually be less compliant, since it takes less vertical compression to flatten the tire under load.

Changing two variables at once (tire width and rim width) will always result in an answer of "it depends." I was just correcting your mistaken belief that increasing rim width will somehow result in an increase in vertical stiffness. It won't. Specifically, it won't increase the vertical stiffness because the additional cavity volume and change to tire ply line allow you to run a lower pressure without worrying about pinch flats. taking 5-10 psi out of the tire trumps anything else related to ride.

[Mark McM]

I was just correcting your mistaken belief that increasing rim width will somehow result in an increase in vertical stiffness. It won't. Specifically, it won't increase the vertical stiffness because the additional cavity volume.

I don't think you understand how a tire works. Cavity volume has no direct affect on vertical stiffness - a tire is not an air spring, because there is no appreciable change in total volume/pressure under load (to prove this to yourself, attach a pressure gauge to a tire, apply a load to the wheel, and observe the pressure change - there will be little to none).

A tire supports a load by a change in shape, not by a change in volume/pressure. For the same inflated tire width, a wider rim will use a narrower tire casing. So for the wider rim, there will a shorter tire sidewall, which will result in a smaller vertical deflection under a given load (at the same inflation pressure). Thus, for the same inflated tire width, the tire on the wider rim will be vertically stiffer.

[jerrym]

My experience doesn't exactly address your A/B question, but when I switched from 19 mm rims to Industry Nine i25 23.2 mm rims, I noticed a big difference in comfort right away. I was using 25mm tires, switching from Easton EA90 slx to the I9's. Speed is a harder thing to measure, but I can't imagine I'm going any slower. I'm sold on the wider rims.