TT Fit

gloomyandy

Have been reading the thread about raising TT bars with interest and thought I would ask a more general question.

I'm thinking of getting a TT bike to do more events next year. I've used TT bars on my road bike this year, but I really didn't want to mess around with moving my saddle etc, so I'm sure I wasn't in a very good position. I spent a lot of time getting my road bike fit sorted out including a couple of bike fits (one of which did not really help, but anyway), and can happily ride my road bikes for many hours. So I was wondering how do people come up with a good TT fit? After all the position can be pretty different to a road bike so I assume it will feel very odd to begin with. Are there any general starting points (like the infamous KOPS), for getting an initial saddle position etc? Are bike fitters any good for this, especially for someone that has not actually got a bike, or tried riding in that position for any length of time? Do people find that their position changes over say a first season as they get more used to it (or can put up with the pain)?

Any tips for choosing a TT bike, it seems a bit chicken and egg without knowing what sort of position I will be riding. I'm pretty short (5'6") so will be on a smallish frame which often seems to cause problems with bike fit (short head tubes and a not very flexible back). I know exactly how to setup a road bike for me, but I suspect those measurements will not carry over very well.

napoleond

Good starting point is measure the centre of BB - middle of saddle height of your road bike, then on the TT bike shove the saddle all the way forward then set to the same BB-centre of saddle height as your road bike and work from there.

Grill

Sizing a TT bike with no past reference of the needed stack and reach is difficult. Typically the best thing to do in this case is to get a TT frame that is of similar size to your road bike (S to S, M to M, etc.) with an adjustable stem and bars that are quite adaptable (PDQ's come to mind). From there you can properly dial in a fit.

I don't recommend seeing a fitter for two reasons. First is that the best they can do is give you a starting point. No matter how good the fitter your position will change on the road. In my case it was so drastic I can't for the life of justify the expenditure, and this was with a fitter that supposedly specialises in TT/Tri fits. Second is that once you're comfy, you're far better off tweaking your position to lower your Cda. This can be done either in a tunnel or with someone who specialises (Aero-coach). I look at clubmates who are a lot stronger than me and chuckle at how I'm faster due to a far more aero position.

There are a lot of resources online to help with a baseline position. From there you can post photos for advice here, on TTF or Slowtwitch. That's the budget approach anyway.

BeaconRuth

gloomyandy wrote:

So I was wondering how do people come up with a good TT fit?

Erm, there's often a lot of trial and error involved!

Joking aside though it's pretty true to say that it's rare to come across a time triallist who doesn't tinker with their position more or less constantly. There's a reason for that though: it's incredibly important and makes a massive difference to performance.

Are there any general starting points (like the infamous KOPS), for getting an initial saddle position etc?

You'll probably need your saddle further forward than on your road bike, and hence a little higher because bringing it forward shortens the distance to the BB.

Are bike fitters any good for this, especially for someone that has not actually got a bike, or tried riding in that position for any length of time?

I'm with Grill in that it's rare for a bike fitter to come up with a perfect position just like that but they may be able to get you most of the way there if you really don't want to have a go for yourself.

Do people find that their position changes over say a first season as they get more used to it (or can put up with the pain)?

There doesn't need to be pain involved - but see my first comment with regard to changes over the first (or any) season.

Any tips for choosing a TT bike, it seems a bit chicken and egg without knowing what sort of position I will be riding. I'm pretty short (5'6") so will be on a smallish frame which often seems to cause problems with bike fit (short head tubes and a not very flexible back). I know exactly how to setup a road bike for me, but I suspect those measurements will not carry over very well.

Different makes will have different dimensions - some will suit those with a short torso, others will suit those with a long torso. You could do worse than go round anyone in your club who has a similar build to you (especially if they seem to have a good racing position) and ask if you can sit on their bike, look at its dimensions etc and then go looking for something similar.

Ruth

gloomyandy

Ruth/Grill/Nap,
thanks a lot for the comments all makes lots of sense. I'm currently looking at a couple of bikes the Planet-X stealth (small) and a 2013 Cannondale Slice (51). The stealth seems to be slightly longer (about 1cm) but other than that seem similar. Any thoughts on these or similarly priced bikes as a starting point?

Grill

Either will be fine. Sure top end frames are faster, but as your body is responsible for the vast majority of drag, position is paramount.