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When is a tire fit and chainstay clearance too tight?

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When is a tire fit and chainstay clearance too tight?

Old 10-18-16, 06:28 PM
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Barrettscv 
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When is a tire fit and chainstay clearance too tight?

I'm considering a 700x38 tire that measures 37.5mm wide. The frame will not allow a 700x40 that I use on another bike (it measures 40.5mm). I tried this size and the shoulder knobs gently scrub the chainstays.

I've calculated that each side of the 700x38 tire will have about 2.5 to 3mm clearance. The widest part of the tire of the 38 is a slightly smaller radius than a larger diameter tire and the chainstays spread out as they move back.

Well, any opinions? Is 2.5 to 3mm clearance on each side enough?

.
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Last edited by Barrettscv; 10-21-16 at 09:25 AM.
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Old 10-18-16, 06:36 PM
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It's enough for no muddy conditions but get anything caked in that tread and you run outta room pretty quick.
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Old 10-18-16, 06:43 PM
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Yes, this tire and bike combination would only see dry conditions (except for the random pool of water that might linger a few days after wet weather). I have another bike for knobby tires, but I avoid soggy weather as much as possible.
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Old 10-18-16, 07:47 PM
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Originally Posted by Barrettscv View Post
I'm considering a 700x38 tire that measures 37.5mm wide. The frame will not allow a 700x40 that I use on another bike (it measures 40.5mm). I tried this size and the shoulder knobs gently scrub the chainstays.

I've calculated that each side of the 700x38 tire will have about 2.5 to 3mm clearance on each side. Since the widest part of the tire of the 38 is a slightly smaller radius and the chainstays spread out as they move back.

Well, any opinions? Is 2.5 to 3mm clearance on each side enough?

.

Michael

Its fine if your back wheel has very little wobble (lack of being true). However, if you are looking at a gravel bike they do suffer a lot of abuse, and it is not unusual that during a ride you can hit something and your tire be knocked out of true by 2 MM. I personally would give yourself more room between the stays and the tire than that. Another option is get a slightly smaller tire and just run them at lower pressure. You end up with more patch on the ground and that's what your after, increasing the surface area that is in ground contact. I know quite a few folks that run their tires down to 30-40 LBS on gravel bikes. This is especially not an issue if you are going to go with a tubeless set up like you indicated. Especially if you go with the Schwalbe G ones as they are very supple.
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Old 10-19-16, 07:02 AM
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When very little Mud keeps the wheel from turning ..
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Old 10-19-16, 11:56 AM
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Originally Posted by Jackmen View Post
Michael

Its fine if your back wheel has very little wobble (lack of being true). However, if you are looking at a gravel bike they do suffer a lot of abuse, and it is not unusual that during a ride you can hit something and your tire be knocked out of true by 2 MM. I personally would give yourself more room between the stays and the tire than that. Another option is get a slightly smaller tire and just run them at lower pressure. You end up with more patch on the ground and that's what your after, increasing the surface area that is in ground contact. I know quite a few folks that run their tires down to 30-40 LBS on gravel bikes. This is especially not an issue if you are going to go with a tubeless set up like you indicated. Especially if you go with the Schwalbe G ones as they are very supple.
Hi Jack,


Yes, the 700x38 tire could create some unintended consequences. Running a 700x35 tubeless tire, like the Schwalbe G-One, should minimize the risk of flats.
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Old 10-20-16, 02:23 PM
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Originally Posted by Barrettscv View Post
Well, any opinions? Is 2.5 to 3mm clearance on each side enough?
As long as you trust your wheels to stay straight, you shouldn't have any problems. A multi tool with a spoke wrench is good insurance too.

I like to cram large tires into my cross frame during the off season.
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