Can a grown man suddenly sprout two inches ... or is there something wrong with my bike seat?

I've recently been having a little nag in the back of my head which has been telling me that my bike seat's too low. But this can't be as I haven't touched it for years. And as far as I know, I've passed the legal age of growing. But there it is again - a feeling of the old knees sticking up too much, of my weight being too damn ... low.

So, at a pit-stop to buy a new gear cable (mine keep snapping with monotonous regularity), I took the opportunity to raise the seat by a couple of inches and ... what an amazing difference! I felt preposterously high above the cars (purely psychological, of course) and ludicrously distant from the road. I worried about whether my feet would actually reach to the ground when I stopped, but mercifully I was still in contact. But good grief - the extra cycling power! I suddenly felt like I could go like the wind - admittedly not that sensible while negotiating the T-Junction which takes you into Marylebone High Street. It must be said though that it's not all joys - I also felt much more knackered more quickly.

But my suspicion is that by raising your seat a tiny bit, you could make a substantial impact on speed and efficiency.

Karma rating: ****

By the way - just found a good post on bike seat height at Bike Radar - and it confirms the idea that a too-low saddle can have a serious impact on energy efficiency. So there you go.

Couple of odd observations from this morning's ride ... bird noises and invisibility

A bird-bike

There is a bird which produces exactly the same noise as my bike makes when it's a bit unhappy about changing gears. Kind of grinding, whirring, whining, rasping, shrilling, scraping. I noticed a bird making the identical sound. In Notting Hill Gate somewhere. Spooky.

Assume invisibility

Thought it would be worth writing a longer piece ("Oh God", I hear you cry, "No") about how to start cycling in London and keep safe. My first rule would be to assume that you're wearing a kind of Harry Potter Invisibility Cloak. Assume no-one can see you, even if you're wearing two dozen lights, a full body suit of luminous lycra and you're sounding every horn and bell at once. It's safer that way. I wonder if anyone else has a "top rule" which I could shamelessly steal and add to this blog?

My derailleur has become a pain in my derriere

Yup - I went over some nasty bumps as I walked the bike along by the house-boats in Little Venice - and when I got back on my trusty steed, there were the tell-tale signs. My chain was "whirring" whenever I pedalled. I couldn't get into my third set of gears. And the clearest sign of all? I was rapidly losing my temper and therefore my karma. To cap it all, when I stopped and then re-started, sometimes my pedal would be "loose" and I'll whack my nether regions into the saddle. Pain.

Anyway - I've tried shoving the wretched thing across, but to no avail. I now need some advice on how to bring it back to a more workable state. Anyone an expert on derailleurs? Otherwise I'd better do some investigations.

Karma rating: poor.