Bike Fit

It’s common that those of us from a mountainbike background are less likely to have ever had a bike-fit, certainly in my case that is 100% true.
With questions arising over whether I can make lurch into a mile muncher, what does the inter-web offer as advice.

From VulpineCC

  • Bike fit importance increases exponentially as the distance increases
  • With distance comes repetition and you are ‘locked’ onto a bike in the same position for hours, often. Each tiny misjudgement in position becomes ever more exaggerated with time. A tiny niggle in your knee can become excruciating pretty quickly.
  • Anyone, everyone, undertaking any sort of mileage or time in the saddle must treat getting their position right with the utmost seriousness.
  • Knee over pedal (KOPS) always mentioned as directly over the axle for best position (see below)
  • Hub position in relation to Bars – best if obscured. Can this really relate to a longer relaxed MTB fork?

The legendary Sheldon Browns archives have comments from Keith Bontrager, who as a MTB designer makes me sit up and take note. His Myth busting article on KOPS

The KOPS rule seems sensible enough; it puts the knee in line with the pedal at maximum pedaling force, which must help, right? Wrong. The KOPS rule of thumb has no biomechanical basis at all. It is, at best, a coincidental relationship that puts the rider somewhere near his or her correct position

Seat tube angle becomes an important issue in Bontragers bike fit analysis, In my case the Lurcher is 73 Degs, also the angle commonly used on Cyclo-X bikes and Road bikes in my 56cm size. So that dosen’t really help as we can’t change that.

From another site:

Listed below is a quick guide as too some normative standards relative to our preferred standard of (knee forward of foot, where knee = Tibial Tuberosity and Foot = Fifth Metatarsal) for different types of bikes.

  • Road Bike            (0 mm to -10 mm)
  • TT Bike                 (+50 mm to +100 mm)
  • Tri Bike                (+50 mm to +100 mm)
  • MTB Bike             (-20mm to -10 mm)

As I understand that our TT friends like to be in a more forward position and over the Bottom bracket this implies that for MTB its normal for KOPS to be behind the pedal. Now of all the time I have measured myself with the basic plumbob my KOPS position is 15 to 20mm forward of the pedal. All very confusing so I’m giving up on that as a valid ideal of a bikes “comfort” for mile eating. If it doesn’t cause pain don’t mess with it.

Another site has some good real world advice for long distance comfort. PeterWhiteCycles

I particularly like:  “If a bicycle had the saddle directly over the cranks, you wouldn’t be able to lean your body forward without supporting the weight of your torso with your arms. Because the saddle on a typical bicycle is behind the cranks, your seat is positioned behind your feet and your body can be in balance. Try this test. You’ll need a friend to hold the bike up, or set it on a wind trainer. Sit on your bike with your hands on the handlebars and the crank arms horizontal. If you have a drop bar, hold the bar out on the brake hoods. Try taking your hands off the bar without moving your torso. If it’s a strain to hold your torso in that same position, that’s an indication of the work your arms are doing to hold you up”

As hand pain and nerve damage is a big concern for me over distance that’s a good indicator that I will be checking out for different bike setups.

So I think it’s just a case of convincing myself on fit, hamstring stretches, play around as I have been and putting in some good long rides and see the effects (Injury check list). See I told you us mountainbikers don’t go in for Bike-Fits!


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