SLX crank differences

The secret rider
The secret rider Posts: 812
edited March 2014 in MTB buying advice
Afternoon

Now I have decided not to use BB30

I've decided on the best bang for buck price vs weight vs strong for me is SLX

I don't need any rings as I have a 104 BCD race face NW ring.

Can anyone tell me what the diffrence is between the m660 m675 etc etc they look different but seem to weigh the same ?

Also if it helps I've decided at 5,10 to go with 170mm versions

Comments

  • benpinnick
    benpinnick Posts: 4,148
    most of the 67x variants denote different chainring combos. Cranks arms are usually the same.
    A Flock of Birds
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  • nicklouse
    nicklouse Posts: 50,675
    http://bike.shimano.com/publish/content ... ntain.html

    http://bike.shimano.com/publish/content ... type-.html

    Number of rings.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
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  • Cqc
    Cqc Posts: 951
    I'm 5'9" with short legs and 175mm is fine and gives you more power
  • rockmonkeysc
    rockmonkeysc Posts: 14,774
    If you want double and a bash guard then you will need a triple chainset.
    Transition Patrol - viewtopic.php?f=10017&t=13070235
  • Chunkers1980
    Chunkers1980 Posts: 8,035
    RockmonkeySC wrote:
    If you want double and a bash guard then you will need a triple chainset.

    There is a specific double with bash though
  • The secret rider
    The secret rider Posts: 812
    Thanks for the replies

    So basically if I only wan the arms and the axle I can up which ever are cheaper and look nicest. As the rings and bash will be coming off and being sold/binned as I am running 1 x 10

    In relation to 170mm this is the right size calculated from inside leg measurement
  • Cqc
    Cqc Posts: 951
    The secret rider wrote:

    In relation to 170mm this is the right size calculated from inside leg measurement
    Suit yourself
  • The secret rider
    The secret rider Posts: 812
    Cqc wrote:
    The secret rider wrote:

    In relation to 170mm this is the right size calculated from inside leg measurement
    Suit yourself

    I used this but ultimately I guess it's what feels right

    http://www.machinehead-software.co.uk/b ... lator.html
  • supersonic
    supersonic Posts: 82,708
    Why does the 175mm give you more power?
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  • stubs
    stubs Posts: 5,001
    The secret rider wrote:

    In relation to 170mm this is the right size calculated from inside leg measurement

    Those crank length calculators are for road bikes MTBs usually have cranks 5mm longer. Though to be honest I bought a bike once with 170mm cranks when I usually use 175mm. Didnt even notice till I changed the chain rings about 6 months later.
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  • The secret rider
    The secret rider Posts: 812
    stubs wrote:
    The secret rider wrote:

    In relation to 170mm this is the right size calculated from inside leg measurement

    Those crank length calculators are for road bikes MTBs usually have cranks 5mm longer. Though to be honest I bought a bike once with 170mm cranks when I usually use 175mm. Didnt even notice till I changed the chain rings about 6 months later.

    Ahh ok did not know this !

    Good to hear you did not notice the difference ! I guess it also allows for more ground clearance when peddling through trails
  • Cqc
    Cqc Posts: 951
    supersonic wrote:
    Why does the 175mm give you more power?
    More leverage
  • rockmonkeysc
    rockmonkeysc Posts: 14,774
    Cqc wrote:
    supersonic wrote:
    Why does the 175mm give you more power?
    More leverage

    What percentage extra leverage do they give?
    Transition Patrol - viewtopic.php?f=10017&t=13070235
  • stubs
    stubs Posts: 5,001
    The secret rider wrote:

    Good to hear you did not notice the difference ! I guess it also allows for more ground clearance when peddling through trails

    Theoretically yes I suppose though 5mm isnt much you could get 5mm of clearance by putting more air in your tyres or running a bit less sag on the suspension.
    Fig rolls: proof that god loves cyclists and that she wants us to do another lap
  • supersonic
    supersonic Posts: 82,708
    Leverage is not power.
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  • Cqc
    Cqc Posts: 951
    Moment= force x distance
  • supersonic
    supersonic Posts: 82,708
    But power is the rate you use energy, not work done. So depends on cadence and torque applied, and whether your dimensions can make use of the ergonomics to supply those factors.

    Of course a longer crank gives you more torque for a given applied force - but can you keep the cadence the same? Or pedal in a smooth circle to give an even application of torque?
    GT ZASKAR CARBON TEAM

    VOODOO CANZO

    Come and see me at https://www.facebook.com/biketyke/
  • benpinnick
    benpinnick Posts: 4,148
    supersonic wrote:
    But power is the rate you use energy, not work done. So depends on cadence and torque applied, and whether your dimensions can make use of the ergonomics to supply those factors.

    Of course a longer crank gives you more torque for a given applied force - but can you keep the cadence the same? Or pedal in a smooth circle to give an even application of torque?

    ^This. The notion that longer cranks = more 'power' is totally bunk. For a single 1/3 stroke its entirely true, but over the course of a whole ride the amount of energy you expend hoiking your leg up and over on a disproportionately longer crank will outweigh the power benefits if its not the right size. What matters is what FITs you, and what stops you coming to a halt abruptly when you smash a rock (something more common with ever lower BBs).
    A Flock of Birds
    + some other bikes.

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