Rear wheel rubbing on underside of rear brake

StillGoing

Can't figure what the problem is here. I have two road bikes, both 11 speed SRAM. One bike, all the wheels fit without a problem. The other, no matter which rear wheel is inserted, the tyre surface will rub on the UNDERSIDE of the rear brake calliper. I've checked the dropouts and they seem ok and have put a new rear hanger on just in case, but still get the same problem. The wheels used to fit perfectly well without problem, but suddenly this. The bike is a 2010 frame that hasn't had overly high mileage on it or any arduous treatment, so I can't see that the dropouts are going to be worn unless they were made of jelly?

Just to be clear, this was never about the width of the tyre. It is about increased height of a tyre.

munkster

Are you using wider tyres than before? A 2010 frame may not have foreseen the current trend towards 25mm+ tyres... Mine didn't and it's very tight under my Force 22 calipers with 25mm Schwalbe Ones :-(

StillGoing

That is a very good suggestion. Tyres have recently been changed to 25mm Conti tubs and clinchers on all 3 sets of wheels. Cheers.

lesfirth

I can not stop laughing.

You are winding us up are you not Philthy?

StillGoing

lesfirth wrote:

I can not stop laughing.

You are winding us up are you not Philthy?

No unfortunately not. I'd completely forgot I'd switched all my tyres to 25mm. The 2010 bike has spent the last year as my turbo bike with a 22mm turbo tyre on, so when I decided to take it out on the road after all this time, I forgot about the size change. Should have been obvious, but alas not. :oops: Although, are you assuming I meant side to side interference as that is not what I said and would have been quite obvious?

Bobbinogs

Easy mistake to make, I can imagine quite a few folks will be changing wheelsets like for like shortly only to find that this year's model has a marginally increased rim width of a couple of mm. Hardly noticeable to the naked eye but it is surprising how that 23mm tyre will flatten out a bit to 24/25 mm, or a 25 go out to 26/27mm... and any setup with a tight clearance suddenly becomes an issue.

StillGoing

Thing was width wise there isn't an issue, it's the increased profile of the tyre making the contact patch rub the underside of the calliper bang in the middle. To make it more confusing the front is fine.

fenix

Different clearances clearly.

I did hear that some teams were using ultegra calipers in P-R as they are higher than the DA calipers. So not all calipers are made equal....

StillGoing

This table shows that the 25mm has a bigger circumference and therefore height from the rim than a 23mm tyre.

http://www.cateye.com/data/resources/Ti ... rt_ENG.pdf

darkhairedlord

Fenix wrote:

Different clearances clearly.

I did hear that some teams were using ultegra calipers in P-R as they are higher than the DA calipers. So not all calipers are made equal....

I thought they were using 5800 brakes with the logo's blacked out?

StillGoing

I've just had the gauge on the 23mm and 25mm on the same depth rim and there's 3mm difference in height from the rim bed. Clearance from the 23mm to the underside of the calliper; 3mm.

drlodge

philthy3 wrote:

I've just had the gauge on the 23mm and 25mm on the same depth rim and there's 3mm difference in height from the rim bed. Clearance from the 23mm to the underside of the calliper; 3mm.

I've got about 2mm clearance in the Rourke with 23c tyres, 25c just won't fit.

fudgey

let some air out.
i had this the other week when i put new 25mm tyres on my nice wheels and decided to put the wheels on my carbon bike for a ride.
used it once and it was fine, then the next time i pumped up the rear tyre as it was 60psi to 100psi.

it was only once home that i noticed the wheel wouldnt turn as the tyre hit the rear brake bridge. let some air out till it span freely and all was good.

StillGoing

The difference in height is 3mm exactly and the available clearance with 23mm is 3mm. Running a 25mm deflated enough to give clearance would be virtually flat and with clinchers, risking pinch flats.

I've got 23mm tyres I can switch back to for this bike so no issue there. The post was because I hadn't remembered I'd switched all my wheels to 25mm and there was a difference in profile height from the rim bed.

munkster

How far away from the rims are your brake pads too? If they are far away from the rims then I found that the caliper arms sat "flatter" and therefore closer to the tyre. If you adjust them so they're not so far from the rim then this seemed to help a bit because the arms are made into more of a "v" shape. Hard to explain but in short if you run your brakes far from the rim I found that this can exacerbate the clearance issue...

StillGoing

Brake pads were fine. Any closer and the brake would have been on. I like instant brake pressure.

darkhairedlord

Some 25's are taller than others. for those with clinchers Check out http://www.bicyclerollingresistance.com as they have tyre measurements of height and width for all the tyres they have tested.

StillGoing

darkhairedlord wrote:

Some 25's are taller than others. for those with clinchers Check out http://www.bicyclerollingresistance.com as they have tyre measurements of height and width for all the tyres they have tested.

Useful table that for the next change in tyres although I'm nt sure about Pro 4s being 55mm in height?.

keezx

Conti's are known for being bigger then the model designation says.

trailflow

You could try adding another serated washer or 2, or 3,where the caliper attaches to the frame. That will effectively move the caliper away from the frame and further upwards giving you more clearance. Another experimental trick is to add some material to the drop outs. Like a 1 mm thick piece of rubber. That will move the wheel away from the brake but obviously you need to make sure the skewer still has enough material/area to clamp onto properly.