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700c vs 27" wheel questions(5 posts)

700c vs 27" wheel questionsShad
May 13, 2002 11:44 AM
I'm just wondering how I can tell if an old frame uses 27" wheels or 700c wheels. Also, is there an easy way to tell if a wheel is 27" or 700c? (Diameter measurement?) Can I use a 700c front wheel and a 27" rear wheel on the same frame if they both fit in the dropouts? I was given a couple old frames and some misc wheels.

Thanks for any info you can provide! Shad
If you're lucky...retro
May 13, 2002 2:10 PM
...you can use them interchangeably. My Trek tourer has cantilever brakes, and I can change back and forth with just a brake adjustment. Good thing, because 27-inch wheels and tires are getting really hard to find.
You CAN tell by the diameter, but I can't remember the numbers. Easiest way would be to find somebody with a bike, borrow a wheel of known size for a second and see if it fits. 27s are a little bigger. Just because the wheel goes into the frame doesn't mean it fits--you have to be sure the brakes line up properly. Assuming they do, I don't see any problem with running one size in front and another in the rear--they're very close in size, and tubes (but not tires) are interchangeable.
Thanks Retro! NMShad
May 13, 2002 2:16 PM
re: 700c vs 27" wheel questionsAkirasho
May 13, 2002 3:58 PM
http://www.sheldonbrown.com/tire_sizing.html

In general, 700C wheels require a drop bolt (but not always) or some other mod to the brake arms to allow proper rim/brakepad interface.

http://www.sheldonbrown.com/home-drop.html

There are still sources for 27" rims...

http://www.sheldonbrown.com/harris/new.html

We abide.

Remain In Light.
How to tell:Alexx
May 14, 2002 3:39 AM
Somewhere on the rim, the diameter will be embossed. For 700c rims, that diameter is 622mm. for 27" rims, the diameter is 630mm.
Mixing wheel diameters will affect heatube angle, and trail, too. Handling will likely suffer. If the stuff is junk, though, it probably doesn't matter.