Wednesday, 6 October 2010

What makes a cyclist go faster?

I had an odd experience on the canal a couple of days ago. (I know, this sounds like the beginning of a dodgy story possibly involving unsavoury characters, a heron, and a canoe). But read on, it's cycling related, I promise.

This is not the Regent's Canal! Source
OK, so in the very quiet bit just West of London Zoo, I see a long stretch of empty towpath. It's dry and I can go as fast or slow as I want. I decide to experiment with speed. (No, this is not, I tell you, a dingy tale of class A drugs and depravity). I'm on a hybrid Giant Zero, as regular readers will know. To you and me, that means it's a "normal" looking bike with straight handlebars. I think to myself - what if I kind of pretend I'm on a road bike/racer, and kind of squat down like they do on the Tour de France or this fellow in the picture going down a mountain?

A new feeling on the bike

It's interesting doing it because as soon as I lean forwards, I realise that I have to loosen up my shoulders, which I'd been holding very tight. I lean so my head is nearly on the handlebars, and all of a sudden it's a completely new feeling with my legs pushing in a different way. I look at the speedometer thingie, and see that I've suddenly increased my speed by about 4kph, and I still feel I've got more in me.

Position or wind resistance?

Clearly my bike's not designed for me to bike like that and I'm sure that if I kept it up for a long time it would get mighty uncomfortable. But then I start doing a bit research about speed. These seem to be the key ingredients for going faster:

What are the factors that make you faster or slower?

  • Fitness and practice. Clearly you need these just to get started on faster biking
  • Drag or resistance from tyres. This seems to be why some people swear by thinner tyres, pumped up to astonishing levels of pressure. It reduces the resistance on the road. But there seems to be some dispute about whether the actual width of the tyre really makes that much difference. The consensus from what I can tell is that pumping up your tyres high every day will make quite a difference
  • Resistance created by rider. This is where my experiment seems to come in - if you're bent down, there's less body for the wind to push against. This is apparently called a "racing tuck".
Just like me, he's got his head right down. Similarity ends there. Source

  • Weight of bike/rider. Again there's disputing how much of a factor this is, but clearly you're going to have to work harder to go faster if you're carrying around half a tonne of bricks in your panniers
  • Gears, pedals, "rotor rings" and suchlike. There's quite a lot of anecdotal evidence that upgrading your pedals, getting a more efficient set of gears and changing to "rotor rings" (don't worry, I'd never heard of them before either) might improve your speed
  • Wind drag on the bike itself. From what I can tell, the effect of this is pretty negligable
  • The type of bike you have. Mountain, Road, Hybrid, reclining, other. Some cyclists claim that there's about a 15MPH difference between when they ride their MTB and when they ride their road bike!
Take it easy though

I guess it should also be said that you're not going to be going very fast in the city if:

1) you're battling against a headwind
2) you're in a monsoon-like downpour
3) you're weaving between several bendy buses on Oxford Street

But these seem like an interesting start in terms of speed, and I'd be interested to hear whether others have views ... when you do want to go fast, how should you do it?

Further reading and links:

- Good archive thread with quite a lot detail in bikeforums
- Good review of what rotor rings look like and are on Bike Radar
- Long but reasonably interesting video about aerodynamics etc on Wonderhowto site


girlandsteed said...

Yep, that helps! Will also experiment. On some empty roads...

KarmaCycle said...

I enjoyed the twitter that also pointed out that going down a hill can alter your speed ...

John the Monkey said...

Of course, the changes you make to go faster can also be used to go the same speed with less effort :-)

(On my tired days, that's definitely the preferred option...)

billy said...

My recumbents are both faster than my folders, and more comfy, but the folders are generally more useful.

KarmaCycle said...

Ah John - thanks for this post - sorry I didn't catch it earlier. Yes, there's something in that. Tune it all up nicely, then go at a leisurely rate, and still get there quicker! Nice thinking.

And Billy - yes, those recumbents can sure shift! I was amazed to find one whizzing past me when I thought I was going at a pretty respectable clip. Guess a recumbent's not the most practical thing to tuck under your legs on the train!

Dreich said...

When it comes to weight you have to remember that muscle weighs more than fat so if you have more muscle you should make the bike go faster. Ofc this only covers straights anyone who watches any road cycling knows that going fast uphill means weighing very little.

You can also do a very fast short burst of speed by going over the handle bars.

Alternatively make motor bike noises whilst you go along and you can get a much better feeling of speed. This however may be due to people going away from you faster in the opposite direction.