Convert your old 10 speed into a modern bike easy!!!! Your old ten speed 27 inch bike has 630mm wheels. A modern bike has 622mm wheels -- YOU CAN CHANGE THEM  (it is only 8mm difference, 1/3 inch) -- Going to a new wheel (622) will allow you access to hundreds of tires. If you choose to stay with your old 27" bike wheels, getting tires in the future will be harder. We have made this section so it will be easy to get what you need to to convert your bike. Just get new wheels, you may not even have to move the brake pads. The products we have chosen most closely resemble the types of tires, rims and wheels common to the older 27 inch bicycles. You cannot install 700c tires on 27" wheels, you need 700c wheels. Use this page to find your new 700c wheels and rims 27 x 3/4 = 700 x 20 27 x 1 = 700 x 25 27 x 1 1/8 = 700 x 28 27 x 1 3/8 = 700 x 32