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32 mm tire on 20 mm rim?

Old 11-23-14, 09:43 PM
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32 mm tire on 20 mm rim?

I'm fixing a daily commute bike for a friend who has a very limited bike budget. His front rim is severely worn and probably won't make it through the winter. It is a 27" rim, fairly wide, in which he runs a 32 mm tire, and his tires are also worn out. His rear rim is also 27". In my pile of stuff I have a old 700C 36H wheelset that is in good shape, and plan to put that on his bike, assuming I can remove his freewheel without incident. The brakes reach fine.

Edit: weird, his existing freewheel is a five speed that has no discernible removal notches or splines. The inner ring (that is the bearing race) is the smallest diameter thing that I see - although admittedly the freewheel is so full of goopy filth that I can't see much, but feeling around in there with a pick doesn't reveal any splines. Well I happen to have another five speed freewheel here to use, if need be. His bike has indexed stem shifting that appears to be setup for five speed (?).

My question is, are these rims too narrow to run 32 mm tires? They are 20 mm wide, from brake track to brake track. Normally I'd put 23 to 28 mm tires on these rims. I don't have 700C 32 mm tires to try out and see - was going to buy him a pair of Pasela 700C x 32, if you guys think they will work.

He is one of these guys who rides everyday but has no interest in or aptitude for bike maintenance. Including regular tire inflation. So I think I need to keep him on 32 mm tires, that will be more forgiving of under inflation and perhaps more flat resistant than skinny tires would be. I'll also drill out the valve holes to accept Schraeder valves, since he doesn't know from Presta . . . I don't think he owns a bike pump, he inflates his tires at the gas station.

Last edited by jyl; 11-23-14 at 09:52 PM.
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Old 11-23-14, 10:02 PM
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Post a picture of the hub. When I hear "no removal notches" I wonder if it's a Shimano Uniglide or SunTour cassette hub.

32mm tires on a narrow rim are acceptable but not perfect. There's a chance that they'll feel "wiggly" since the tire is quite tall on that narrow rim.

I would find a tire with tougher sidewalls than the Pasela.
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Old 11-23-14, 10:03 PM
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You should be fine running a 32mm tire on that rim. If you scroll down, you'll find a chart with recommended tire widths. The chart is pretty conservative. I've run 32mm tires on rims that narrow before. Still I'd have a talk with your buddy about proper tire inflation.
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Old 11-23-14, 10:05 PM
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My touring bike has rims of that width and I've run tires ranging from 23mm up to 38mm on them without any problems.
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Old 11-23-14, 11:11 PM
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This is the freewheel on the hub. The hub looks just like any other old hub.

I will look for alternate tires. They do have to be inexpensive. I keep my friend's bike going with used parts from citybikes and parts from my pile, try to cost him less than $50/year.
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Old 11-23-14, 11:19 PM
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If the hub has a steel shell, it might be one of those "integrated" units with some characteristics of a cassette, but not one. The freewheel ratchet mechanism is half in the hub and half in the cassette. The sprockets are more like those on freewheels, and there's no interchangeability with anything else.

For all practical purposes, consider the hub and "freewheel" to be a single unit, and either use it as is or trash the wheel. If you want to service it, you can remove the axle from the left. You can also access the freewheel unit by removing the ring with a pin wrench (but I wouldn't).
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Old 11-23-14, 11:22 PM
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Originally Posted by jyl


This is the freewheel on the hub. The hub looks just like any other old hub.
It looks like there's splines inside the freewheel. It's probably a cheap China- or Malaysian made unit, which should use a standard Shimano tool.
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Old 11-23-14, 11:34 PM
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Originally Posted by Jeff Wills
It looks like there's splines inside the freewheel. It's probably a cheap China- or Malaysian made unit, which should use a standard Shimano tool.
Jeff has better eyes than I do, but I looked more closely and he appears to be right. However, the re are two freewheel spline patterns. The current one which uses a thin walled remover that fits into the gap between the axle spacers and f/w splines. And an old one with was a smaller diameter and needs the axle spacers removed before the freewheel can be pulled.

There's also the "Falcon" pattern which looks like Shimano, but is 'close but no cigar" and uses it's own remover.
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Old 11-23-14, 11:42 PM
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Well you both have better eyes than me because I have the thing on my bench and could not see anything.

Edit: I didn't mean to disagree (about there being splines). I mean it literally - I have terrible vision . . .

Okay, tomorrow I will go to town on this. My friend says he uses his lowest gear to climb mt tabor so the alternate freewheel I have will not be ideal.

Last edited by jyl; 11-24-14 at 07:50 AM.
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Old 11-23-14, 11:50 PM
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Originally Posted by jyl
Well you both have better eyes than me because I have the thing on my bench and could not see anything. Okay, tomorrow I will go to town on this. My friend says he uses his lowest gear to climb mt tabor so the alternate freewheel I have will not be ideal.
OK, so it either has splines or it doesn't. If it does it's a freewheel. If not, and if the hub is also steel, then my earlier post may be right.
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