The Minoura Live Roll R720 Rollers are extendable to take bikes from 24” wheel up to 700c (950 to 1,080 mm wheelbase). They use a very thick 105mm roller to give a light and smooth pedalling feel. To help you maintain a straight line the R720 rollers come with a silicon ring to act as a position indicator.
Using rollers is the traditional way to do winter training. As well as letting you keep the pedals turning on dark winter evenings they are also great for improving your balance, bike control and pedalling actions as you need to balance yourself and keep a smooth and consistent pedalling motion to stay on them.