Wednesday, 25 June 2008

To SPD or Not To SPD... That is the Question

There is a bit of a debate I have had with various people over the years about the use of SPDs (or Shimano Pedalling Dynamics to give them their full name).

What are they? Well, SPDs are a means of attaching your shoes to your pedals. There is a cleat which you attach to the sole of your shoe which then clips into a special pedal. This essentially makes you one with your bike... so to speak.

Why use them? Well the theory is like this. When you use normal pedals the only time you exert a force on your pedals is on the down stroke. This, obviously, is transmitted through your gears to your back wheel causing your bike to move. Not exactly rocket science. Anyway, the problem with this is that you are only providing power for around half the time the crank rotates. The idea behind SPDs and other like systems is that by connecting yourself to your pedals you can also pedal on the upstroke as well thus increasing the efficiency. In essence, when you pedal using normal pedals only one leg is providing power. Using SPDs then both legs can provide power; the leading leg on the down stroke and the lagging leg on the upstroke. This is very handy when you have to tackle a lot of hills.

So why doesn't everyone use them? Well, I guess most people are comfortable using normal pedals. I must admit that it took me some time to get used to SPDs and not just because of the change in pedalling technique. The main thing I had to get used to was how to disconnect yourself from your pedals in an emergency. As you can well imagine, being attached to your bike... where you go, your bike will follow. There have been a couple of occasions when I have been cycling off road and gone over the handle bars. Of course, my bike followed me and flipped and hit me on the back of my head. Luckily I was wearing a helmet both times which saved me from injury. Okay, perhaps I'm not exactly endearing them to you because of that fact but once you learn to twist your legs if anything happens then you can disengage quickly.

On the road SPDs are excellent and well worth checking out. They do take some time getting used to but on long journeys they can help a lot. Hey, Tour de France participants use them and they should know what's best right? Off road, I do use them but then you have the problem of trying to clip and unclip yourself quickly when coming up to tight corners or whatever. In the end it's all to do with what you find comfortable and easiest to use.

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