Bicycle Mechanics - rim identification

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still treken
07-22-08, 05:08 PM
i have a 94 trek 930, i recently bought some new tires (cheap ones) from dicks s.g. they are 26 x2.1 which is the size i need, however the tire package said not recomended for straight rims.not sure what they mean. the sides of my rims are as straight as they can be, you could put a level on them...do i have the straight rims they are describing

still treken
07-22-08, 05:36 PM
p.s. the rims are Matrix SingleTrack Comp, 36-hole, so are these considered straight rims ???
Sturmcrow
07-22-08, 05:58 PM
By "straight rims" they are referring to the bead seat inside the rim. Unless your bike is over 20 years old, I wouldn't worry about it. Modern rims are referred to as "hooked" and if you feel inside the rim wall you can see and feel where the "hook" is.

HillRider
07-22-08, 06:04 PM
The "hook" is a ridge of metal inside the rim at the top of the sidewall and helps to retain the tire bead under pressure. Just about every road and MTB rim made since about 1980 has hooked bead rims so you are fine.
still treken
07-22-08, 06:07 PM
thank you
Sturmcrow
07-22-08, 06:09 PM
Here is a picture of a hooked rim cross section. A straight wall rim wouldn't have the little hooks on the upper left and right.
http://www.tagwheels.com/Images/Content/composite_rim_advantages_1.jpg