Muddymoles mountain biking in the Surrey Hills and Mole Valley

Bike fitting shock

Posted by Tony | March 17, 2012 | 6 comments so far

Like many road cyclists I know, down to the half cm, my bike fitting measurements. Hence it came to me as a shock when I had to benchmark my MTB fitting against my road bike measurements this week.

Recently a few of us Muddymoles have been lead away to the perverse pleasures of road biking. Including some long training rides and culminating with four of us Moles riding the hilly Spring Onion sportive in respectable times of 3:30-3:40 for 67miles.

As a long time road cyclist and road racer (although not as long as MTBing) I get on very well with the road bike. I hop onto my road bikes, I feel confortable and feel like I have pedalling power. All is good.

So on Wednesday night, after a month or so off the MTB, it was a shock to get back on the dirt. It felt horrible! I could seem to get any power down and my back/hips hurt like hell after just 16miles.

Time for a re-think. Obviously something was wrong with my MTB position, and armed with my road bike position of years, I measured up my MTB position.

Obviously some parts of road bike measurement don’t apply. However as always the first thing to check was the saddle height, from the centre of the BB to the top of the saddle (76.5cm – burnt into my heart), with sag for the suspension drop taken into account. Next was plus reach to the bars. All seemed OK. Saddle level was slightly nose up, so I changed that to slightly nose down (as suspension sags the saddle moves back and the nose comes up slightly).

Then came the measurement of the offset vertical drop from the nose of the saddle to the BB. 7-8cm on my road bike. 12.5cm on my Trek Fuel! 4-5cm might not seem like alot but I can assure you that it is, plus this is made worse by me riding 172.5mm cranks on my road bike and 175cm cranks on my MTB.

So I moved my saddle forward 4cm and moved the cleats back in my shoes a 1cm.

Earlier this afternoon I took the MTB out for a spin. It was transformed from Wednesday. My legs were spinning. I felt like I had some power and my hips/back didn’t ache. Even in the mud (it actually rained today), without killing myself, I got my best Strava times on the climbs I rode.

Changing from a road bike to MTB always feels a little odd. However I’d certainly been making things hard for myself, so if you do ride road and MTB, check you position carefully!

Filed under Mutterings in March 2012


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  1. StevenD says:

    Tony, your changes to your riding position are similar to mine last year (also with a Trek Fuel Ex). I moved the seat forward and adjusted the cleats but also changed to a smaller stem (80mm laser from Superstar), maybe consider that as well ? In my case I am btw sizes with the Fuel; 15.5 being too small and 17.5 next up but I am now happy with my riding position.

  2. Matt says:

    Great to hear you’ve worked out some of the issues you’ve had with the MTB Tony, as we discussed on Wednesday night it turns out to be a problem with the hip in relation to the knee after all.

    You had me so worried about your Strava times I had to check to make sure! Fortunately the damp weather would have held you back a bit!

    Echo StevenD’s thoughts about needing to look at the stem as moving the saddle that much forward might bring the bars forward too much. Perhaps you need a 120mm stem to compensate? 🙂

    • DaveW says:

      Matt said

      “Perhaps you need a 120mm stem to compensate”

      and drops?! ;o)

      Seriously though, it does make so much difference and I’m sure sometimes seatposts and saddles just gradually move on their own. After reading this I got my tape measure out and moved my brompton saddle back 10mm and raised the saddle on my pompino by 15mm. (The pompino is hard to compare with my other bikes due to the brooks saddle having some sag, so I won’t know if I got this right until I’ve had a go).

  3. DaveW says:

    Just thinking about my statement

    “I’m sure sometimes seatposts and saddles just gradually move on their own”

    In the case of the Pompino, cartwheeling it into the road with a full panier on the back at 25mph might have helped the seatpost move ‘on its own’….

    • Tony says:

      Hi Dave. Well that’s one way to move a seatpost. Either that or fitting a Dropper post with a dodgy pin/internals (Gordon and D’Andy)!

      Not that I’m nerdy about this or anything but I had to stop out on the road ride yesterday evening to raise the seatpin on my old (newly rebuilt) steel frame 0.5cm. It felt great after that.

  4. Huey says:

    “with sag for the suspension drop taken into account.”
    Does suspension sag really change your saddle to b/bkt distance? Surely it’s fixed in that design of frame?
    I’d agree you don’t want such a full leg extension as on a road bike, but that’s just as the general ride quality is worse so it allows for a little slack in the system.

    “as suspension sags the saddle moves back and the nose comes up slightly”
    It sounds like your forks are set harder than the rear shock then as these should also sag the same so in effect your saddle would remain level.


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