Help replacing parts

CSMR
CSMR Posts: 13
edited November 2017 in Workshop
My bike shop tells me my bike is in bad condition and I need the following components replaced:
Casette, Chain, Chain ring

The overall cost of service would be more than half the used value of the bike so I would like to source the components and just get the shop to attach them.

The bike is a Trek 1.1. According to http://www.bikeradar.com/gear/category/bikes/road/product/review-trek-bikes-1-1-11-42493/ the specs are:

Casette: Sun Race CSR86 12-25, 8 speed (although I counted 26 as the larger number)
Cranks: FSA Tempo, 50/34

Questions:
  • Does the casette need to have exactly the same number of teeth? The shifters are Shimano so perhaps any 8 speed Shimano casette will work?
  • If I get a casette together with a chain, will the combination just work together with the other components? I can see a listing for "Shimano 8 Speed chain (CN-HG40) 116L and cassette (CS-HG50-8) 13-26T".
  • Can I get any chain ring with the right number of notches?

Thanks for any help!

Comments

  • sungod
    sungod Posts: 16,551
    assuming they're correct, which is not guaranteed...

    1 - whether you go for the same ratio on the cassette or not depends on whether you're running out of low gears on climbs, probably not with a compact, but worth considering, most 8 speed shimano/compatible will be ok
    2 - yep, if you stick to shimano 8-speed bits they work
    3- chain rings will be 110bcd, 5 bolt, non-hidden bolt, any generic 50/34 110bcd rings are likely to be ok

    easiest is to id specific parts and post back to ask people if they are ok

    for the cost of hex keys, a cassette lockring tool, chainwhip, and chaintool, you could diy, it's not complicated, even getting the tools could be cheaper than what lbs will charge you, then you're more self-sufficient
    my bike - faster than god's and twice as shiny
  • CSMR
    CSMR Posts: 13
    Great, thanks! I live in a flat area and rarely need to change gears, so what I need will be in the range of any casette. I guess if they are closer together then I may use more of them and they will wear out less fast.

    My last bike was a Peugeot, reached an old age without problems. I suppose bikes are more sophisticated and brittle now.
  • keef66
    keef66 Posts: 13,123
    CSMR wrote:
    Great, thanks! I live in a flat area and rarely need to change gears, so what I need will be in the range of any casette. I guess if they are closer together then I may use more of them and they will wear out less fast.

    My last bike was a Peugeot, reached an old age without problems. I suppose bikes are more sophisticated and brittle now.

    12-25 cassette is a good choice for flattish terrain. Today's sprockets are thinner and have lower profile teeth than they used to back in the day; good for slick shifting, but they seem to wear out faster. Chainrings ditto, plus they are frequently aluminium alloy which isn't nearly as tough as steel.

    Get the tools and DIY, then next time you need a new chain and cassette you can do it for a tenner!

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