i have two frames originally designed for 630mm rims. one has original 630mm araya 20a rims and gripfast 7/8 in. (about 20mm wide) tt tires. the other has 622mm kinlin rims with vitoria diamante 20mm tires. i can and have swapped them around and, handsfree ridingwise, one frame is stable and the other is not.

here they are: top is 79 trek 710 with the 622mm rims and below it is the 86 trek 310 elance with the 630's.





if forget to mention, the 710 is the unstable one. i blame it on the steep headtube angle. the 310 elance is very stable and my favorite ride.