Originally Posted by
Marco
If you want to see how fast you can go downhill, if you spin a gear of 52 x 13 up to 180rpm, (which is considered to be as fast as you can possibly pedal), on 700c x 25mm tyres you will reach around 57mph. Around 35 years ago, sadly before accurate speed measuring equipment was available, I achieved something similar on the A52 Ashbourne - Derby road riding one metre behind an Irish fish van (which looked more like a removal van) with a very bad gearbox. It was great until the road went upwards and I lost the tow and got hit by the turbulence you would expect from 3 metres behind something of that size going over 50mph. Not recommended
In short, stick to 52 x 13 or 48 x 12 and spin your legs, (which will help your downhill fellrunning technique), and save your pennies