bocian

Hello everyone!
Recently I tried to "urbanise" my Trek 1000 (2004) a little bit, so I switched 23 mm tires for Continetal Contact Speed 28 mm. You might sense where is this going - they don't fit, but it's the height that is the problem. Front looks OK, but rear one is very slightly rubbing against either brake calliper or part of the frame calliper is mounted to. It's touching it in intervals, not constantly (probably the wheel is not completely straight). I would post a photo, but I'm new.

I would like to get your opinion on idea, that wider rim (internal width) will cause the tire to sit lower on the wheel, therefore descreasing its height. Any experience with this? Currently I have 15 mm internal width rim, so there's possibility of going wider, but I'm not sure if it's worth trying.

Thank you!

Crankycrank

Can't advise you on getting new rims. That would depend on whether you're willing to spend the money. Or you could try putting a spacer on your rear brake mount bolt between the brake and brake stay which usually positions your calipers away from the tire. Also try checking other brand/models of tires here. https://www.bicyclerollingresistance.com/ It takes a little digging but you can compare their listed actual tire heights to other tires and find one that is a few millimeters lower. Any tire you select from this site will have the actual measurements down the page a bit listed as "Size and Weight Measurements" not to be confused with the "Manufacturer Specs",

ThermionicScott 

I've read that the opposite happens, that wider rims can allow a tire to grow taller:


If you're willing to shell out for new wider rims, I'd stick with 25mm tires, which would probably puff out to 28mm anyway.

bocian

Actually the spacer is an interesting idea, the closest part really is the mounting bolt. Now I've lowered the pressure to 70 psi (102 is maximum, had it on 90) and the rubbing noise disappeared, but you can imagine that the gap is still incredibly small. If I managed to move the break calliper somehow, what would you consider to be the safe gap? I suppose that during ride all the vibration can still cause the tire to hit the frame or calliper.

Thank you for recommendation, that website is doing theriffic job! Eventually I will be forced to get different tires, but I would love to ride these, as they seem to me as good combination for a city, cobbles, curbs and gravely bike roads. If the rim width effect was strong enough to give me let's say 2 mm and let me fit tires more suitable for my commuting purposes, then I would consider giving it a shot, depending on the cost obviously.

Crankycrank

I would say 7 mm is about the thickest spacer I would attempt to use but you can usually get away with thinner thicknesses. Try stacking some washers you have laying around first to determine what thickness spacer you need or if it will even work for your situation.

Spoonrobot 

The tire will be shorter because the relative pressure is lower as the overall volume of the tire increases with wider rims. What this means in practice is you get a shorter tire at the same PSI but it's not very much - maybe 3-7% change. Could be enough to make a difference but using spacers or a reverse drop bolt makes more sense.

Jicafold

Just thinking, you could take a Dremel to your dropouts to free up a few millimeters. That would be free.

Andrew R Stewart 

I have recently gone through this very issue with my new bike. The 700c x 28 Gatorskin has only about 2mm of clearance under the rear caliper. The rims are the current Mavic Open Pros, which are a bit wider then the older versions. I have the previous version of the Open Pros with the same tires (and from the same "batch") for comparison. The old rim version is about 3mm narrower then the current one and the tires are about 2mm smaller in height.

So the wider rim also increases the tire's height as TS said. One measurement is worth a thousand assumptions

I designed the frame around the old rim so soon I will have a few new versions that I won't be using having sourced the old version to lace to the hubs.

BTW I found the ride feel with the current rim version, at the same tire pressure, to be harsher then the old version. Not at all what I wanted too. One more reason for me to not go wider in the rims, my 63 year old 150 lb. body likes the smoother feel of a more round tire section. Andy

smashndash

I think that has more to do with the fact that the tire is effectively bigger now. If you had a 28 before, you have a 30-31 now. Tire pressure needs to go down with tire volume.

Andrew R Stewart 

I believe that is what I said in a different way. To add numbers. The old version of my Open Pros with the 700 x 28 Gatorskins measure (note that I didn't reference the tire with "28mm") 27mm at riding pressures. The new rim version with the same tire measure a touch over 29mm wide.

Of course with a wider/taller tire one can run lower pressures and have the same road to rim dimension (or suspension travel in a manor of speaking). I still found the new version of the rims to be stiffer then I like. Because I can swap them to what I know I like I will do so. Andy (who's glad he lives in a country with so many choices and the freedom to pick more then one)

HillRider

Since the bike has vertical dropouts that would change things in the wrong direction by making the wheel sit higher in the frame. The OP would have to add shims to the dropouts above the axle to make the wheel sit lower.

Jicafold

That's only true if he lengthens the dropouts in the vertical direction. I was thinking he could create extra space backwards in the horizontal plane.

Marcus_Ti

Which one? Mavic now sells 6x different OpenPro rims.

Funny thing...even the new OpenPro (UST) is low spoke tension like its predecessor IIRC. I think Mavic recc'y only 900N on it? Granted the OP line is now hilarious, they sell the alloy OP UST for $99/each at 430g, but also offer a carbon fiber OP UST for $600USD at a staggeringly lighter 425g. Most expensive 5 gram weight loss in history right there.

Andrew R Stewart 

The "new" version I don't like is the UST model, Al 435gm. I chose this because I wanted a 28 ft and 32 rear spoke count and the Open Pro C wasn't available in a 28 hole (any longer as in previous years it was made in 28*).

I suspect the spoke tension limit spec reflects the reputation that Mavic gained for cracking at the spoke holes. The easiest way to address a problem is to change the published limits Even still I really like the Mavic rims and build them up as I always have, to a tension that seems right IME. Andy