Bike Position Checkpoint 1

From what I’ve read of time trialling, it’s clear that the two most important determinants of how fast you will go are:

  1. How much power you can output for the duration of the trial
  2. How aerodynamic you are

These can be competing concerns – it might be possible to assume a very aerodynamic shape, but that could compromise power output.  There is a lot of information in Adam Topham’s book about how to reduce drag.  It can be quite technical, and I am not too knowledgeable on fluid dynamics.  Suffice to say that the key components of your ability to cut through the air are:

  1. How aerodynamic is your shape?
  2. What is your frontal area?

Obviously you want your shape to be as aerodynamic as possible, and your frontal area to be as small as possible (sigh, yes, yes…)  I’m not going to go into any more detail on this now, largely because that’s the limit of my understanding!

I’ve been training on my bike for a week or so, adjusting things here and there to try and make the shape as aerodynamic as possible, using my limited understanding of how to do that.  I haven’t ridden the bike on the road yet (apart from a short hop from London Bridge to Kings Cross), so I have no idea if the position I have adopted on the turbo works on the road (e.g. how stable is it?), but we all have to start somewhere.  The weather has not permitted an outdoor test, yet.  Every now and then I will post about how the position has evolved.  In order to demonstrate this, I plan to record videos of the changing position so I can compare it over time.  Hopefully they will form a useful record as I learn more about this subject.  You will notice that in the videos I am wearing a ludicrous helmet.  I realise that it makes me look like a right, er, helmet, but this piece of kit is an important part of the jigsaw and it’s necessary to make sure that it sits correctly in whatever position you adopt.

My initial thoughts are:

  • There is a big gap between my chin and forearms, bigger than you generally see.  This opens up what I believe is termed the ‘chest cavity’, which I don’t think is good.  The bars are currently in their lowest position.  I could move the bars forwards and up, and/or tilt the extensions upwards to address this.
  • My back is quite curved, rather than flat.  Perhaps raising the saddle might help, and/or moving it back.  I haven’t really adjusted the saddle height much so far.  I know my road bike saddle height, having had a bike fit done when it was first built, but I think the saddle height on a TT bike might need to be different, because you are stretched forward so much, which I suppose stretches the hamstrings.
  • There is quite a gap between my knee and elbow.  In an ideal world, I think this should be closed, to make the side-on shape as short as possible, to minimise the affect of sidewinds.
  • I think my chin is in a reasonable position, just behind the front hub.

I have just registered on www.timetriallingforum.co.uk.  I think I will ask advice on that forum.

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Posted on February 10, 2013, in Position and tagged , , , , . Bookmark the permalink. 4 Comments.

  1. Carl,
    Nice post. You have to keep fiddling with your position until you get it bang on. I guess there is no substitute for time on the road. Are oyu able to visit a velodrome to get some advice?
    From your car days you’ll know how the tiniest adjustment can be massively influential (either direction) to your comfort behind the wheel (it certainly did me anyway) so good luck with it.
    I found this vid taken of Lance at the Superfrog Triathlon. Might be worth taking a screenshot and comparing side to side for any pointers?

    Stu

    • Hi mate, yes I have been spending a lot of time looking at photos and videos of time triallists. You’re right, small changes can make a big difference, both good and bad. There are some basics you need to get right, but from there, positions vary a lot. You have to find a balance that works. But you can’t tell what works until you try it, so it’s a long, iterative process. Thanks for the comment 🙂

  2. I think a video just in speedos and lid next time Carl…….
    Seriously though, enjoyed your first post mate. And your right you can compare Wiggins, Armstrong, Cancellara and many more, they don’t all have the same shape.
    Comfort has to come into it as well, I was thinking of riding into headwinds, getting down really low is very uncomfortable (for an unhealthy chap like me) but makes a huge differencr to effort required.
    I guess it’s finding the right trade off points between everything.
    Look forward to your next update.

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