Specialized Stumperjumper Carbon Pro

Ian_H
Ian_H Posts: 12
edited April 2016 in Your mountain bikes
Hi everyone ... I'm new to the forum ... been riding for a few years around the Chilterns area (I'm in Amersham)

Got this bike recently (for a good deal I think) from a fellow watch forum member over on TZ-UK.

Here it is ... Specialized Stumpjumper Carbon Pro - came with quite a few extra carbon bits and had been converted to 1x10.
SRAM XX Cassette, Hope Pro Wheels, Hope Braided Brakeset,

I added a Hope Extender 40t cog and a 16t cog - some steep hills remain a challenge : -)

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Comments

  • jimothy78
    jimothy78 Posts: 1,407
    Ian_H wrote:
    I added a Hope Extender 40t cog and a 16t cog - some steep hills remain a challenge : -)

    Hardly surprising, with what looks like a 38T chainring on a 29er.

    Not sure how small you can go with that crankset, but I THINK it's 120mm BCD, which you should be able to reduce down to 36T, or you could pick up a crankset with a smaller BCD to get a bigger reduction.
  • Ian_H
    Ian_H Posts: 12
    jimothy78 wrote:
    Ian_H wrote:
    I added a Hope Extender 40t cog and a 16t cog - some steep hills remain a challenge : -)

    Hardly surprising, with what looks like a 38T chainring on a 29er.

    Not sure how small you can go with that crankset, but I THINK it's 120mm BCD, which you should be able to reduce down to 36T, or you could pick up a crankset with a smaller BCD to get a bigger reduction.

    Hi - thanks for the reply ... been away ... hence late comment from me...
    I only need to get on my feet once or twice on a ride ... so need to think if changing the setup is worth it.

    I'm googling now to work out what BCD means and now realise this dictates the size of chainring I can mount.

    Other option is to swap 40t to 42t which I think is available - but would need a new chain.
  • jimothy78
    jimothy78 Posts: 1,407
    Ian_H wrote:
    I only need to get on my feet once or twice on a ride ... so need to think if changing the setup is worth it.
    For shorter rides that sounds OK, but you might find on longer ones that the ability to just sit and spin is valuable for conserving your strength.
    I'm googling now to work out what BCD means and now realise this dictates the size of chainring I can mount.
    Yes, like I said before, a 120mmm BCD means that you can't go below 36T for the chainring - most MTB cranks these days use a (more-or-less universal) 104mm BCD, which means you can go down to 32T (and even 30T with a little tweak to chainring design).
    Other option is to swap 40t to 42t which I think is available - but would need a new chain.
    Unless you reduced the chainring to 36T at the same time, which would mean your existing chain would still fit. :wink:
  • Ian_H
    Ian_H Posts: 12
    jimothy78 wrote:
    Unless you reduced the chainring to 36T at the same time, which would mean your existing chain would still fit. :wink:

    I've got visions of my feet going round like the clappers trying to get any speed downhill ....
    But thanks again for reply ...
  • jimothy78
    jimothy78 Posts: 1,407
    Ian_H wrote:
    jimothy78 wrote:
    Unless you reduced the chainring to 36T at the same time, which would mean your existing chain would still fit. :wink:

    I've got visions of my feet going round like the clappers trying to get any speed downhill ....
    But thanks again for reply ...

    Like I said before, a lot of people manage just fine with a 32T ring. The fact is, that unless you're riding down very boring stuff (like long, straight fireroads), you simply don't go that fast on a mountainbike (at least, not for very long). Even on downhill runs you're unlikely to be in top gear that much, because you're regularly braking for corners and then you want to be able to accelerate out of them.

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