Upgrade help please - old shimano vs SRAM

iandennis
iandennis Posts: 238
edited March 2011 in MTB workshop & tech
My commuter mountain bike is doing about 160 miles a month to work and back. Currently running shimano 7 speed with an acera groupset (i think). its a grip shifter. I'm getting problems with poor quality shifting, despite cleaning and tensioning cables. The chain and deraileurs are apparently IG specific ? - not really sure what that means ??

I have the following in my spare parts box:

Sram X4 shifters - with cables (inner and outer)
Sram X4 rear derailieur
8 speed cassette and 8 speed chain.

Is it worth swapping this over onto my commuter ?
Assume that the cranks can stay, just need to make the changes at the back ?
Will an 8 speed cassette fit on the hub ?
I know i will need to adjust chain lenght and reset cables.

Any problems likely ?
Thanks

Comments

  • nicklouse
    nicklouse Posts: 50,675
    just use the 7 speed block and miss on clicvk. the spacing is the same for the shifts on a 7 and 8spd set up.

    but the bodies are different so an 8 speed cassette will not fit.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • iandennis
    iandennis Posts: 238
    Thanks Nick,

    Would it be worth changing the body ?

    Trying to do this on the cheap as I already have the parts.
  • The Rookie
    The Rookie Posts: 27,812
    Realistically it's not worth changing the freehub (for most hubs it will mean a wheel rebuild AIUI), may as well source an 8-speed wheel and sell on the 7 (I picked up a perfectly useable 8-speed on ebay for a fiver for the doris bike).

    So why not fit the shifter and rear mech for now as nich says and keep an eye out for an 8 speed wheel (or get a 9 - it's the same freehub) and fit that when you get one.

    Simon
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • nicklouse
    nicklouse Posts: 50,675
    it would make the hub wider and the frame would need resetting and the wheel re dishing.

    Is is presuming that it is a 7 spd body and not an 8/9spd with a spacer and a 7spd cassette or a 7spd spin on freewheel.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • iandennis
    iandennis Posts: 238
    It an ancient Raleigh exodus frame (?) that I picked up for free last year. Doubt that its a 7speed plus spacer due to the age of the thing. Rigid frame and weighs a ton :)

    So best idea seems to fit shifters and rear deraileur but adjust to limit to 7 speeds ?

    Thanks
  • nicklouse
    nicklouse Posts: 50,675
    So best idea seems to fit shifters and rear deraileur but adjust to limit to 7 speeds ?

    yep.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown

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