Is my bike too small?

Discussion in 'Mountain Biking, Trials and BMX' started by gmtfd, 27 Feb 2018.

  1. gmtfd

    gmtfd Senior Member

    My MTB is a B'Twin Rockrider 8.1 which I've had for years and absolutely love. However, recently I've been riding more and have noticed that I'm often perched right on the back of the saddle, which is as far back as it will go on the rails (even beyond the 'max' marker). Does this mean the bike is actually too small for me? I'm 5' 11" and the bike is a large size, so theoretically it's the right size for me.

    Are there any adjustments I could make to stop my bum constantly hanging off the back of the saddle? The stem is 100mm so I would guess fitting a longer stem is not an option? Wider bars maybe? Tilting the bars up?
  2. Spiderweb

    Spiderweb Veteran

    North Yorkshire
    If my parents were taller and I’d reached the lofty heights of 5ft 11” then I would have thought the size Large Rockrider would be perfect for me.
    On an MTB you do move around on the saddle, I often ride in the position you describe, it’s whatever suits. You could try a longer stem or some bar ends so you can extend your reach.
    If you feel uncomfortable on the bike then make some changes but you don’t describe any discomfort so I would leave as is and enjoy.
    Last edited: 27 Feb 2018
    Heltor Chasca likes this.
  3. Threevok

    Threevok Carpe Rotam

    South Wales
    Another thing to check is your seat height - your knee should be slightly bent at the point where your pedal is furthest away.

    I wouldn't worry about it too much though. the saddles are shifted back to the max on both my MTB's. The Virtue running a 90mm stem with bars uncut at 800mm, and the Inbred running a 110mm with the bars cut shorter 740mm (both 18" frames)

    I am comfortable with both bikes
  4. Try using a seatpost with more set back.
    meta lon, Spiderweb and Heltor Chasca like this.
  5. ianrauk

    ianrauk Tattooed Beat Messiah

    Atop a Ti
    Put up a pic of you sat on the bike.
    Drago, raleighnut and Spiderweb like this.
  6. ChrisEyles

    ChrisEyles Veteran

    +1 for trying a longer stem if you need to be well back on the saddle, unless the seatpost you're currently using doesn't have much set back.
  7. KneesUp

    KneesUp Veteran

    Fit rather depends on your proportions - I have relatively short legs for my height which means I tend to have the saddle back on the rails also. If it's right for your leg length then as others have suggested you can adjust for torso length by changing the seatpost and / or stem.
    Threevok likes this.
  8. meta lon

    meta lon Guru

    This would be a good start, then the bars.
  9. Nigeyy

    Nigeyy Guru

    Massachusetts, USA
    I'm not sure a longer stem is necessarily a good idea (does the rider want to be more forward or is hanging off the back more indicative of needing to be in a more rearward position? There's a difference relative to how you can use your leg muscles on a downstroke). It depends on how much setback you currently have (bike geometries vary with seatpost angle) and whether you even have a setback on your seatpost. Obviously you can put your saddle as far back on the rails as you can as well. It's hard to tell since we haven't seen a pic (and even then individual preferences can play a part).

    Since you seem to hanging off the back mostly, I'd recommend trying to move your body back rather than bring it forward with a longer stem -.e.g. saddle back on the rails, or a more setback seat post first. Having said all that, it's not unusual to be hanging off the back mtbing, so it could be just entirely normal :smile:
  10. meta lon

    meta lon Guru

    Most MTB bikes have a straight post.
    And most droppers are straight .

    I think they tend to be a straight post design?
    Though a set back post works ok, I don't like the angle in relation to crank but that's just me.

    Helps with stand over tho
  11. Nigeyy

    Nigeyy Guru

    Massachusetts, USA
    To be clear, when I mentioned setback on a seatpost, I was referring to where the saddle rails join the seatpost, not the seatpost tube itself. Thompson is a good example of a manufacturer that has no setback on some of its seatposts at all. But again, this also depends on the angle of your seatpost tube with frame geometry as well. Fit is such an individual thing!

  12. ColinJ

    ColinJ A big clot!

    Try a longer stem - 100 mm is fairly short! I have 4 bikes and the stems are 110, 120, 120 and 130 mm in length.

    Tilting the bars up would effectively bring them closer to you, which is the opposite of what you are trying to achieve.
  13. I like Skol

    I like Skol I'm adamant I haven't got any PPI....

    You need to be able to hang your ass off the back of an MTB so you can get your weight back when riding down steps and impossibly steep slopes! :okay:
  14. ColinJ

    ColinJ A big clot!

    But only a complete nutter would do something like that! :whistle:

    Pat "5mph" and Threevok like this.
  15. OP

    gmtfd Senior Member

    Many thanks for the advice everyone. I hadn't even considered the seatpost! Mine definitely has some setback but I'm not sure how much. I will measure it tomorrow and then see if I can find one which offers more. Failing that I will try a longer stem, but it definitely makes more intuitive sense to tinker with the seatpost first.
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