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TRIATHLETE'S BLOG

  • Matt Fisher

A bike fit with a difference

I must have had five or six Retul bike fits over the years, including fittings on previous road and time trial bikes with Garth Kruger at Vankru Performance Cycling near Southampton. So when I booked myself in for a fit on the new 2018 Giant TCR, I thought I knew what I was getting into.


But this was a bike fit with a difference.


Arriving at Vankru’s studio, I met Mark who would be my ‘fitter’ for the day. As Mark set up my TCR on the turbo, he handed me what looked like a pair of cycling shorts to put on (together with some highly sexy disposable undies, but the least said about those the better!).


Mark explained that the Myontec Mbody shorts had sensors embedded in the material to detect how each of the main muscle groups in the upper legs (quads and hamstrings on each leg) were firing through the pedal stroke. The idea is to use the results to guide the fitter, rather than adhering to a strict set of measurements and angles as you would with systems like Retul.


Mark had me ride in different hand positions (hoods, drops etc.) and at different intensities (top tip: take your Garmin if you normally ride to power!), noting what the shorts were reporting on a mobile app (screenshot below).


App readout of the mbody shorts

The initial results were quite stark.


My hamstrings were doing the lion’s share of the work (especially on the right when riding on the hoods), leaving the quads relatively under-recruited. This set alarm bells ringing for Mark, as he said that over-reliance on the hamstrings can lead to greater fatigue on longer rides and then real problems on the run.


We could also see that, while the Garmin Vector 3 pedals were reporting roughly equal left/right power, my muscles on the left weren't working as hard as those on the right.


BEFORE the tweaks

So he set about altering the bike position not based on laser measurements, but instead on his understanding of my physiology (we had done a fairly thorough assessment of joint mobility and had also discovered a 3mm leg length discrepancy earlier) and what he wanted the muscle recruitment to look like.


Essentially, the main changes were to bring the saddle forward and upwards slightly, encouraging more use of the quads through the pedal cycle. Mark also altered the handlebar angle (and reset the position of the hoods) to provide both a slightly more aggressive (on the hoods and forward drops) and relaxed (on the back of the drops) position options. He also altered the angle of the seat slightly to provide a better contact patch between it and my backside (important to lower the pressure on my over-worked back).



AFTER the changes

I mentioned above my small leg length discrepancy. This wasn’t new to me, but previous fitters had thought the difference too small to be worth taking any action on. Mark disagreed and fitted a 3mm ‘wedge’ between the shoe and cleat on each of the two pairs of cycling shoes that I had taken along (more at home still to be done, including my tri shoes).


Out on the road


Mark did warn me that it takes a couple of weeks post-changes for the body to adapt. So flying to Mallorca the very next day wasn’t the best plan. And so it was perhaps no great surprise that my legs felt a bit more tired than normal through the week, specifically my right quad (which was now having to do it’s ‘fair share’ of the work, I guess!) and the inside of my upper left leg.


That seems to have largely settled now and since the change I have set both a new 25-mile time trial PB (albeit on my time trial bike) and a new PB up a local climb. Even on a different bike, you have to wonder whether the changes made to the TCR are helping the quads play a greater role through the pedal cycle.


Next up – the time trial bike


We only had enough time to fit on the TCR, so I’m going to have to go back to get fitted on the Trinity. And this is causing me some concern.


Why? Well, because I’ve set several PBs on the Trinity already (since switching over from the S-Works Shiv) without any kind of bike fit. So obviously, it can’t be all bad. I don’t want to risk making a change that actually slows me down. Of course, it could be that my position on the Trinity is awful (I doubt it, but let’s play along) and that the guys at Vankru could find yet more PBs through some position tweaks. It feels a bit of a gamble, but one I guess I’m going to have to take eventually.


In the meantime, I’m going to continue adapting to the new TCR position (if nothing else, the bike looks super-aggressive now!). Thanks to Mark and Garth at Vankru for the fit and advice so far.