Frame Clearance and Tyre Widths

harringtonp

I'm running 25mm Schwalbe Pro Ones in a 2013 Rose Xeon CW 3000 frame and the pinch point (literally) is the chainstay. Measurements as shown in attached images are precise (using a calipers) and you can see that the tyre measures at a little over 28 and the minimum frame width a little over 31.

The effect of these is that I have to be really careful to try and get the wheel positioned correctly, it needs to be pushed to one side while the skewer is made very tight and then tested under load. This process often takes a couple of goes to get it just right but so far it has not been my undoing in any races this year (I'm waiting for it though...)

It seems to be getting harder of late to position correctly and I'm not sure whether this is due to play in the hub (which I can't detect), slight buckle (though it still looks tru) or the tyre having got a bit wider as it aged. Any opinions guys ?

BTW if you know your frame width of your road bike in relation to tyre widths please post back here with details. I'm wondering is the rose xeon particularly narrow or typical of race bikes around that time.

ED E

Probably a stupid question: same PSI with a decent pump throughout? On a prior frame with 28s I got away with 90ish but at 105psi there was contact.

harringtonp

ED E wrote: »

Probably a stupid question: same PSI with a decent pump throughout? On a prior frame with 28s I got away with 90ish but at 105psi there was contact.

Different pump but usually never go above 80 PSI (according to the pump). I could try running them lower as they are tubeless.

Wonder would a very slight bend in one of the chain/seat stays result in this too ? The tyre is only prone to rubbing on one side so I have to press the wheel to the other when locking the skewer.

Bambaata

Ive a Cannondale Supersix Himod and max conti 4000's i can it are 23s on the rear. Id an issue recently and noticed theres a slight bit of play in the dropout on drive side which kicks it ever so slightly to one side. Have you checked that theres no play in the dropouts? I tiled bike onto handlbars/seat and could see the play when quick release loose. I put a wedge off card into the area to take the play out and worked a treat, going to have to get something done though as i wont have this luxury in a race!

cdaly_

harringtonp wrote: »

The effect of these is that I have to be really careful to try and get the wheel positioned correctly, it needs to be pushed to one side while the skewer is made very tight and then tested under load. This process often takes a couple of goes to get it just right but so far it has not been my undoing in any races this year (I'm waiting for it though...)

Put the wheel backwards in the dropouts and see is it offset the other way. If so, the wheel dish is off and can be corrected by adjusting spokes...

harringtonp

Bambaata wrote: »

Ive a Cannondale Supersix Himod and max conti 4000's i can it are 23s on the rear. Id an issue recently and noticed theres a slight bit of play in the dropout on drive side which kicks it ever so slightly to one side. Have you checked that theres no play in the dropouts? I tiled bike onto handlbars/seat and could see the play when quick release loose. I put a wedge off card into the area to take the play out and worked a treat, going to have to get something done though as i wont have this luxury in a race!

Did as you did Bambaata, turned bike upside down and started looking at it carefully. Dropouts on both sides are very slightly bigger than hub ends. I would imagine this is the case on most bikes as otherwise it would be too tight for quick wheel changes. In order for the wheel to be dead center the hub end on the drive side needs to be pushed to the back and on the other side the hub end pushed forward. This results in an even but tiny spacing between the tyre and the chainstay. The problem is that to keep it in that position when riding, the skewer needs to be very tight.

Perhaps as suggested by cdaly the wheel dishing is off but the amounts are tiny and I think the problem is more down to the tyre been too wide for the frame. When upside down I spun the wheel and at the point where the tyre was touching, the calipers measured a tyre width of 28.6 mm. As you see from an image in a previous post the calipers showed a frame width of 31.1mm at the point where there was rub marks on the chainstay from the tyre. And the calipers could only measure near the edges of the chainstay, its possible that in the center it is even less than 31.1. However running with 31.1 and subtracting 28.6 leaves 1.5mm. Divide this be 2 and you get 0.8mm clearance on each side. Its not a lot is it ? Which is why for my next bike I will look at this closely...

Bambaata

when you see theres only 0.8mm clearance i think you have your answer! Thats no tolerance at all, any sprint or power down and your tyre will push out a little. time for 23's ;-)

harringtonp

Bambaata wrote: »

when you see theres only 0.8mm clearance i think you have your answer! Thats no tolerance at all, any sprint or power down and your tyre will push out a little. time for 23's ;-)

Yes, I have a newer Pro One 23mm on a Velocity A23 rim (which I use on the winter bike which has greater clearance) and thinking of swapping them around. Email first to the wheelbuilder to see if he knows how well his wheels take 23's

harringtonp

Just googling and there is no information out there from manufacturers on frame clearances. Most show geometry diagrams of frames but nothing about width around wheels.

You'd nearly think it's not important until you see the amount of discussion in forums. You would think that any manufacturer who gave consideration to width when designing frames would be keen to illustrate that in the best way possible. Does anybody have links to examples where this is done ?

Apart from visually viewing bikes and measuring it yourself on other bikes I'm not sure if there is a way of determining this.

ED E

Problem there is the wheels/tyres. One 25 might be 26 odd while the next is actually 28 fully inflated. Buying off the spec sheet there going to lead to pain.

harringtonp

ED E wrote: »

Problem there is the wheels/tyres. One 25 might be 26 odd while the next is actually 28 fully inflated. Buying off the spec sheet there going to lead to pain.

I'm talking about bike specs. It would be useful to know for example if the internal chainstay width is 30mm or 35mm. If it is 35mm you know a 28mm tyre wouldn't rub at that point no matter what the pressure in it is.

Bambaata

Gone are the days that narrower was better. All about the wide wheels/tyres now!

harringtonp

Bambaata wrote: »

Gone are the days that narrower was better. All about the wide wheels/tyres now!

Yes and guys like me are upgrading wheels, putting wider tyres on them and running into problems. Which is why definite information on clearances for prospective new bikes would be useful.

CrowdedHouse

A related annoyance I have is clearance on the brake shoes. My Canyon bike came with DT Swiss RR21 and Conti GP4000 25mm. They're awkward to get out of the frame and to re-fit the rear cleanly I have to deflate the tyre.(And yes I am using the brake QR!)

harringtonp

Just measured the chainstay width on my 2009 Planet X SL Pro carbon frame and it comes in at 34.66 mm. That's a lot more than the 31.1mm on the Rose and was before wide wheels

Weepsie

Need to do the same to my old Trek SL 1000 that's sitting unused. In the offchance I can fit 28s on it, I'd keep it. If not, I think it goes.

Lumen

It's mad that tyre manufacturers are selling a 25mm tyre that's 29mm wide at 80psi.

I guess in this case it's so that people think there's some magic ride quality from tubeless, when it's just more air.

ford2600

harringtonp wrote: »

I'm talking about bike specs. It would be useful to know for example if the internal chainstay width is 30mm or 35mm. If it is 35mm you know a 28mm tyre wouldn't rub at that point no matter what the pressure in it is.

A 28mm GP4000 can measure up to 31mm wide on 19mm internal rims ime; that would leave you 2mm clearance each side. Which might not be enough under acceleration, cornerning or if wheel goes out of true/pops a spoke.

On low spoke count wheels you'll probably be in bother if you pop a spoke.

https://janheine.wordpress.com/2013/03/12/how-wide-a-tire-can-i-run/

harringtonp

Lumen wrote: »

It's mad that tyre manufacturers are selling a 25mm tyre that's 29mm wide at 80psi.

I guess in this case it's so that people think there's some magic ride quality from tubeless, when it's just more air.

I suppose a tyre's width can never be an exact science. They're supple (bit like a balloon) and the width at the widest point will be dependent on the rim width. Having said that they all seem to underestimate by quite a bit.

rodneyTrotter.

Any race bike without discs that can take a continental GP4000 28mm is a keeper in my mind. In reality you’re running a 30/31mm tyre.
Running 28mm Schwalbe ones on a caad 12 but I think that’s the limit .