MTB cranks

dannydc
dannydc Posts: 14
edited October 2014 in MTB workshop & tech
Hi

I've got a Trek 5200 with slicks that I use for commuting and have just changed the rear cassette and chain. Now I need to change the cranks as it's slipping (I know you should change them together - I was hoping the chainrings weren't worn but obviously are). The chainrings are riveted on (cheap Suntour), but the bottom bracket seems fine.

Can anyone recommend decent and cheap triple (8-speed) square taper cranks? It's currently got a 42-?-24, but I never use lowest gears and regularly run out of steam at the top end so a 48t (or bigger?) would be better.

Thanks,
Danny

Comments

  • njee20
    njee20 Posts: 9,613
    5200 was always a road bike, notably the cheapest OCLV carbon one, you sure that's what it is?

    Don't mess around with square taper, just get a Deore trekking chainset - if you change chainset you'll likely need a new BB anyway, that avoids the middle step!
  • Good spot - it's a 4300! And the cranks say SR Suntour.

    I'll have a look at the Deore trekking tomorrow - thanks!
  • njee20
    njee20 Posts: 9,613
    This is what you want, available with 26/36/48 rings.
  • Ouija
    Ouija Posts: 1,386
    njee20 wrote:
    This is what you want, available with 26/36/48 rings.

    +1

    It's what i use and much lighter than the Suntour stuff. It's a 8/9 speed crankset but works better with a 9 speed chain (even if your using 8 speed cassettes and shifters) as the slightly wider 8 speed chain can rub against the shift ramps when in the middle ring and smallest rear sprocket.

    Also future proofs you as it will allow you to go 9 speed at a later date, if you want to (i did, eventually). And replaceable rings so you won't have to keep buying new cranks when the old rings wear out.
  • The Rookie
    The Rookie Posts: 27,812
    If you go to trekking ratios you should need to fit a longer chain.......unless the current one is too long.

    Running out of puff on a 42:11 ratio is somewhere over 30mph, are you sure you really are and that it's not you thinking it?
    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.
  • I can get to around 30 but I'd rather do it a bit more relaxed. My commute in is a long steady slight downhill so I end up rolling parts of our when is rather be pushing on.

    I've got some spare chain links so I can extend it a bit for the bigger chainring.

    D
  • Not the best idea to mix chain ages. A whole new 114 link can be had for about £8 anyway.
  • The chain is new- I've used it twice with the new cassette so it's just the chainrings that are old. Having said that, to remove a few links from the new chain I bought a cheap chain tool which I wouldn't normally do, and obviously it broke on first use so I'll have to get a decent one to add the links back.
  • dannydc
    dannydc Posts: 14
    Just wanted to say that I made the plunge and got the Deore M590 cranks with the 48 ring and got the frame faced, plus a 9-speed SRAM chain and the difference is amazing. The changes are quick and accurate (little bit more tuning needed at the back or a new mech maybe!) and the top gear is loads better on the ride in.

    Thanks for the help!

    Danny