Hi! I'm doing a 100-mile cycle (all in one go) on a single-speed bike (a bike with only one gear) - but I'm doing it for charity, not because I like pain!

That charity is Guide Dogs, a very worthy cause indeed. (Some of you will know I had my own eye problems). Any donations, no matter how big or small, will be most gratefully received.  

The 100-mile route starts in the Queen Elizabeth Olympic Park in East London, where I will follow a modified version of the road race route used in the 2012 Olympic Games. Rather worryingly, Leith Hill and Box Hill feature, both of them leg- and lungbusters, especially on a single-speed bike!

We cyclists will ride along closed roads through the capital, and then continue on to the country roads of the Surrey Hills before heading back into central London to cross the finish line in the Mall. I'll probably collapse a few centimetres after the finish line, but that's okay!