Bike Fit

I’ve had the occasional bike fit in my time as a triathlete. Initially ahead of buying my first road bike when I had not real idea of what bike was appropriate. Since then I’ve had a more sophisticated fit for a made to measure road bike and a very unsophisticated fit for a traditional steel tourer. The latter involved the guy eyeing me up and taking two (possible three) measurements with a tape measure and then telling me to come back in 7 weeks for the bike. It was super comfortable and I still have that bike to this day.

When it comes to TT bike fit though I have to admit to being a little sceptical. The reason being is I’ve never felt you are fitting a TT bike for comfort. If comfort is what I wanted then it’s my touring bike every time (Interestingly my first Kona, and my best, was raced on this touring bike). For a TT bike I just took a look at the Pro’s TTing and decided that I needed to be as aero as that and I should get used to it. Perhaps I was naïve, I have certainly been lucky. I don’t appear to have any problems with bikes. I take the approach of all my bikes are slightly different set up on the basis that a slightly flexible branch is less likely to snap than a rigid one – so I want my body to be able to cope with slightly different positions. I’ve always found pretty tucked positions comfortable on my TT and road bikes.

For me for a bike fit to be truly worthwhile it would need all of the following: power meter, heart rate monitor and some method to accurately measure how much drag you’re creating (e.g. a wind tunnel). Despite this I know people that have done all that and ended up with a better position by trying to mimic pictures of the pros.

Yes I am a sceptic.

With this attitude I was happy to take the offer of a free bike fit from Helen at 10-Point Tri. She’s been absolutely fundamental in my return to running and was very keen to see if she could help me further by looking at my bike fit. Being sceptical doesn’t mean there isn’t value in a fit. It gives you more information, another viewpoint; the sceptic in me just means I won’t automatically do what the fit suggests.

The whole process was good fun and quite involved. Mirrors were cunningly non-existent and changes were made whilst I maintained a set power and how it felt drove the changes. It surprised me how small changes would feel quite different. Helen would approach favoured positions from different angles confirming that I was making a consistent choice.

One of the final things to change was the crank length. Instantly it felt terrible and I said so. More tweaks backward and forward and I consistently found the original length best and the others felt worse. Having given Helen my current bike details I’d assumed that I’d been using 175mm cranks on the set up. No, 175mm was the terrible setting that we switched to at the end. The length I like was a mere 165mm.

I like to think of myself as a critical thinker so it really gives me pleasure when something is highlighted where I didn’t do this. Why have all my bikes got 175mm cranks and have done for over 10 years? Simple, because the first guy that sold me a bike took one look at me and my height and said I needed that length.

It shows how convinced I was as days later I order 165mm cranks and am doing all my riding on them in preparation to racing Ironman Wales. With time what I’ve noticed is that the real improvement comes in the aero position (the whole fit was done like this) where the shorter cranks make me feel a lot less restricted. My knees aren’t coming quite so close to my chest when I’m aero. It also feels like my pedalling is smoother and certainly my cadence has increased a little. Doing a little ‘google’ing’ and I found that there is a lot of discussion out there about shorter cranks. It seems that long cranks for tall people is a case of the most obvious ‘logical’ explanation becoming common knowledge. However, it’s easy to give a logical explanation for the opposite – longer cranks means your knees rise higher at the top of the pedal stroke, this is more pronounced the taller the person and more restrictive in the aero position, thus shorter cranks are required. Don’t worry about the explanations, if you get the opportunity try it and see.

One other thing came out of the fit that had a big impact for me; my preferred seat angle – 81 deg. This didn’t surprise me given how I ride on the nose of the saddle when aero however, the only bike that could give me that position currently is a P5. This has started a thought process that could result in a future column…

This entry was posted in Bike Setup, Triathlete Europe and tagged . Bookmark the permalink.

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