baby bearJoined: 23 Aug 2009Posts: 843Location: your mom
I want to convert the ladyfriend's bike from 27" to 700c tires. She doesn't have a lot of clearance on there, so we need the tires to be the same or smaller. I have read the Sheldon Brown article on tires and I think I get it, but I want to make sure.
Her tires presently say "32-630 (27 x 1&1/4)". In order to have the same clearance in 700c, she needs to run the are 700x32 or smaller, correct?
Thank you in advance for your patience with my ignorance.
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Old Crow
Posted: Sun Apr 08, 2012 10:15 pm
Helen Keller, WHAT?Joined: 30 Sep 2005Posts: 395Location: Ballard
Jon, your assumption is correct. Keep it at 32 or smaller and you should be just fine.
lantius
Posted: Sun Apr 08, 2012 10:42 pm
1337Joined: 22 Jul 2005Posts: 6705Location: right over
In order to have the same vertical clearance? 622mm tires are 8mm smaller in diameter than 630mm. So you should be able to go up to 35mm and be fine. Horizontal clearance is a different beast, and depends on the brakes and chainstay design, mostly.
jimmythefly
Posted: Mon Apr 09, 2012 9:30 am
Joined: 10 Jan 2007Posts: 1491
Jon, I've got a set of 700x32 tires mounted to some spare wheels, if you want to check clearance. Probably lots of other folks in the club also have 32s, 35s, etc.
Note that most tires' actual width is not consistent with their labeling (many are actually smaller than labelled).
daywalkerJoined: 09 Nov 2007Posts: 6108Location: Hatertown
Jon, your lady isn't boy sized. She's a small gal. Put her on 25 or 28 's and she's going to be happy as a clam.
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jsmg
Posted: Mon Apr 09, 2012 11:48 am
baby bearJoined: 23 Aug 2009Posts: 843Location: your mom
Yeah, I think Scott's got the right idea. I tried on a spare set of 28s last night and they had plenty of clearance, plus seemed just generally size appropriate for the bike. I think I'm going to let her test ride those. Thanks, everyone!
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Eric_s
Posted: Mon Apr 09, 2012 3:25 pm
Joined: 07 Mar 2007Posts: 1691Location: the dirty south
Just remember:
27" is 630mm in diameter, so the radius from the center of the wheel is 315mm
700c is 622mm diameter, so the radius from the center of the wheel is 311mm.
A 27" radius with an assumed tire thickness of 32 mm will have an outside radius of 347mm. A 700c with an assumed tire of 28mm will have an outside radius of 339mm, or 8mm less.
Going down in size will get you a lower bottom bracket, slightly decreased stand over, a slightly lighter wheel, and more clearance for things like fenders.
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baby bear
Joined: 23 Aug 2009
Posts: 843
Location: your mom
Helen Keller, WHAT?
Joined: 30 Sep 2005
Posts: 395
Location: Ballard
1337
Joined: 22 Jul 2005
Posts: 6705
Location: right over
Joined: 10 Jan 2007
Posts: 1491
daywalker
Joined: 09 Nov 2007
Posts: 6108
Location: Hatertown
Joined: 07 Mar 2007
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Location: the dirty south
