Friday, February 3, 2012

A bike fit experience

Since this is something that is about as hard to find as an honest politician in this part of the world, I thought I'd share my tri bike fitting experience.

I've been trying to set up my tri bike in the Andamans, and have been playing around with bar height (using an adjustable stem), saddle position, crank length, saddle angle and aerobar positioning.   While moving to a 165mm crank, widening the aero extensions and raising the base bar made a big difference in my comfort, I really wasn't quite fully "there", when it came to comfort on the bike, especially for 3 hours or longer of riding.

So, about 10 days ago, I stopped over in Bangkok for a day en route to Phuket for another week of riding with the usual suspects, with the sole intention of getting a fit done.  The fit session was held at BikesZone.co.th, in Amari Plaza in Bangkok, and the fitter was Andrew Gerkin.

The fit session started with Andrew asking me questions about my riding history, riding goals, history of injuries, etc. and filling in a questionnaire as we spoke.

Then it was time to do a short spin on the trainer while he watched and asked questions about what worked and more importantly, what were the issues I was having with the bike.       He also took measurements of the bike at this stage, so that we would have a baseline to refer back to.

After that, the changes started.

The first step was checking the position of my cleats.   Now, my cleats were set-up for the road and in my preferred position - a little further back from the neutral "ball of feet" position.   This is more knee-friendly and also allows more torque, at the expenses of reduced ability to spin.   Andrew suggested moving the cleats back to around the ball of the foot - initially, I resisted this, as I am quite happy with the cleats where they are, and very comfy, pain-free, etc.   However, his point was that as I am sitting further forwards on a TT bike, it makes sense to bring the cleats up a little as well to balance things out.    That made sense, so we adjusted the cleats accordingly (this took a while as one of the screws in my shoe was stuck and took a lot of force to open up).

The next step was setting the saddle height and level.  I had the saddle, a Cobb V-Flow Plus, angled up slightly, as per John Cobb's set-up recommendation.   But I couldn't implement the second part of his recommendation - viz, turn it slightly to the left or right - due to the aero seatpost on the Planet X Stealth  bike.   Andrew leveled the saddle and used a goniometer to set my knee bend to a starting point of 150 degrees at max extension, which he then tweaked a little after watching me ride a bit.

After that, seat fore-aft was adjusted using the knee-over-pedal methodology.   KoP is on a bit of a downswing these days, as most bio-mechanic experts agree that there is nothing inherently special about being KoP neutral.    In this case, we didn't go for a KoP neutral position, but merely checked to see if things weren't too much out of whack.  Andrew felt that moving the seat a just a little further back would be a good thing, so we did that.

At this point, pedaling revealed that my right knee was not tracking straight - this is something I've been aware of as well:  my left knee tracks perfectly when I pedal, but the right one wobbles a little and tends to move left/right, as well as up-and-down.  This was diagnosed to inadequate arch support and I was prescribed inserts to correct this.

I did some out of saddle efforts and got back into the saddle, and each time, I was sitting pretty much where  fitted - implying that my saddle and pedal positions were on the mark.

After the pedal and seat contact points were set, it was time for some flexibility assessment.  I lay on my back and had each leg raised and pushed back, to measure the minimum hip angle I could tolerate.  

Then I got on the bike and Andrew measured my hip angle in the current set-up.   Surprisingly, it was more than my minimum hip angle above, which implied that I could go lower.   So go lower we did.   Swapping in a fixed (but riser) stem got the bars a couple of cm lower than I had them, and closed my hip angle pretty much to its minimum:  a point at which I still felt comfortable, but beyond which would cause me discomfort and loss of power.

At this point, he also had me pedal and lift myself from the TT bars, to see if I was pushing myself up or using my core - I was indeed using my core, so all ok on that front.

Now, the last thing to do was set the aerobars.

My bars didn't allow for a fore/aft adjustment of the pads, but as it turns out, the pads were pretty much where they needed to be, courtesy of the shorter length of the replacement stem.

For bar width, we ended up going as wide as possible.   Most tri/TT guys keep their hands very close together, but that closes the chest and makes it harder to breathe.  Since I am a little wide in the chest and shoulders, Andrew set my bars quite far apart.  For now, I am happy with it, but I think as I get used to riding the TT bike, I will try to slowly get them closer.

The last remaining item was my aerobar length and rotation.   The S-bends I have were too short, and holding them required me to either crunch my hands a little, or move my positioning on the pads to a less comfortable one.   Andrew put in ski bends - something I was initially opposed to (why?  cos s-bends look more aero!), but the comfort difference was immediate.  I could grab these puppies and really lever them if I needed to get off the saddle.     He also turned (angled) the aerobars inwards, so that my upper arm and forearm were better aligned.    What a world of difference this made!

This whole process took about 3 hours: at each stage of this process, there was a lot of A/B testing (make a change / see if it is better), followed by additional adjustments and retrying.   But in the end, what a world of difference it made!

Now keep in mind that this was a relatively "low-tech" fit (not that it is a bad thing, mind you) - fitting systems can get a lot more high-tech, using power meters, spin scan analysis, lasers, 2D/3D renditions, etc. But in all cases, the experience and knowledge of the fitter and time spent slowly dialing in the fit step by step is what makes a fit session successful.

By the time we were done, my bars were lower than I had them initially (although a little wider as well) and my seat a little further back.   If left to myself, I'd have gone in the opposite direction in each case, in an attempt to gain comfort by reducing the aggressiveness of the fit.   But as it turns out, I gained comfort and got lower on the bike as well.   It felt as though I was riding a completely different bike in Phuket.

I cannot recommend Andrew highly enough - if anyone wants to get fitted by him, drop me an email and I'll send you his contact info.

1 comment:

  1. hi
    I saw your posts and can say that you know a lot about cycles !!!
    I m planing of buying new cycle and i am confused with trek 3700 and adidas genius as my price range is 20K i ride it every day to college and do some stunts some time !!!
    so if you suggest me one it will help me a lot !!!

    ReplyDelete