"Road" chainset on a MTB

bliarout
bliarout Posts: 153
edited June 2010 in Workshop
I'm sure it's been covered many times but I haven't found it yet :)

I want to fit a road chainset on my Claud Butler Cape Wrath D24 MTB and the Shimano Ultegra 6603 OEM seems to fit the bill. It has the ratios I want (52/39/30) and will replace my creaking BB with a better item at the same time.

I was talking with the guy in the LBS and he said no way as it would foul the frame. Is he talking out of his doodah? I know I may need to replace the shifter as well but I can do that if I can't get it working.

Also, £110 seems a little privey, are there more cost effective ways to replace my BB and get the gearing I want at the same time?

Cheers,

Rob

Comments

  • softlad
    softlad Posts: 3,513
    it's possible it might foul the r/h chainstay - but the only way to be sure is to line it up and see. Why not just fit a compact double 50/34..?
  • bliarout
    bliarout Posts: 153
    Mainly because I'd like to retain some of the hill climbing ability of the lower ratios if it's possible. If I go for a 52/39/30 my lowest ratio will be 30/23 (I've already replaced the cassette). I need something bigger on the front but I doubt 48 will be high enough)

    My question is more about the physical fit than the ratios although I'm always open to a different viewpoint.
  • softlad
    softlad Posts: 3,513
    23 on the back is not that small - why did you not go for a cassette that gives you a 25 or 27 or 30..? that would make more sense...
  • AidanR
    AidanR Posts: 1,142
    The guys in the LBS are almost certainly correct. I wouldn't put a road compact on there either as you still risk fouling the frame as the spindle will be shorter and you'd ideally want to change the front derailleur and shifter too.

    It sounds like you want a bike for on the road. Sell the MTB and get a second hand road bike.
    Bike lover and part-time cyclist.
  • bliarout
    bliarout Posts: 153
    Roadie isn't an option, I ride four miles across what feels like the bottom of a volcano most days. And no, a CX isn't necessarily the answer either :)

    I love my bike, I just want a higher top gear. I prefer the ratios of a 12/23 cassette as the change per gear is about 8% as opposed to 18% with an 11/30 which suits me just fine.

    I also drive a TVR, taking things apart and modifying them to suit is second nature :D
  • AidanR
    AidanR Posts: 1,142
    Fair enough. You can try the road triple but there's a good chance it won't work. Other than that I'm out of ideas.

    Of course, a good question may be why do you need a gear higher than 44-11? At 90rpm that's 27.1mph, so unless you are wanting to power down a big hill it may be that your cadence is very low and you should be thinking about changing your pedalling style rather than your gearing.
    Bike lover and part-time cyclist.
  • Buckled_Rims
    Buckled_Rims Posts: 1,648
    Can any "normal" human pedal a (52/39/30) x 12/23 gearing on an MTB? Even a CX Spesh Tricross has 50/39/30 x 11/30 gearing on bigger wheels just you help out.

    But, if that's what you want....I'm sure I've read somewhere others have put roadie gearing on a MTB.
    CAAD9
    Kona Jake the Snake
    Merlin Malt 4
  • maddog 2
    maddog 2 Posts: 8,114
    it's possible, but it does depend on the frame design and chainstay thickness. Some frames are quite narrow, others are wider.

    The only way to know is to try it.

    Having said that, you could go to a bigger MTB c/set... there are a few makers of 28/38/48 sets (FSA, Shimano etc.). Not quite a road triple but better than you currently have.

    http://www.chainreactioncycles.com/Mode ... elID=44147

    http://www.chainreactioncycles.com/Mode ... elID=40496

    http://www.chainreactioncycles.com/Mode ... elID=23102

    Plus they should be okay with a MTB front mech, whereas a road triple really needs a road triple front mech to work well, and they aren't compatible with MTB shifters.
    Facts are meaningless, you can use facts to prove anything that's remotely true! - Homer
  • bliarout
    bliarout Posts: 153
    I do have a low cadence thanks to old motorbike injuries, I think the *sensible* option is to go for a 48T Deore which gives me a better BB and slightly higher gearing than standard. If I want to go any higher with my gearing I can fit 700 wheels.

    Oh, and I cycle in the fens near all the wind farms, if you have a tail wind you can do 20 without ever pedalling!
  • bliarout
    bliarout Posts: 153
    I do have a low cadence thanks to old motorbike injuries, I think the *sensible* option is to go for a 48T Deore which gives me a better BB and slightly higher gearing than standard. If I want to go any higher with my gearing I can fit 700 wheels.

    Oh, and I cycle in the fens near all the wind farms, if you have a tail wind you can do 20 without ever pedalling!
  • softlad
    softlad Posts: 3,513
    BliarOut wrote:
    If I want to go any higher with my gearing I can fit 700 wheels.

    you sure about that..?
  • bliarout
    bliarout Posts: 153
    Nope... lol. The Sheldon Brown ratio calculator does seem to point to that though. If I knew the answers to my questions I wouldn't need to ask them :D
  • maddog 2
    maddog 2 Posts: 8,114
    if you run discs then a 700c disc wheelset will slot onto a MTB frame. You just need a rear hub that is 135mm OLN.

    If you run rim brakes it's not as straightforward but doable, depending on the frame
    Facts are meaningless, you can use facts to prove anything that's remotely true! - Homer
  • AidanR
    AidanR Posts: 1,142
    Switching to 700c wheels may not give you the gearing change you're after - it depends on the size of tyre you're currently running. If it's a narrowish slick, say 1.35", then a 700c wheel and tyre would have an effect, but bear in mind that a 2" tyre on a 26" rim has roughly the same circumference as a 23c tyre on a 700c rim. You could run fatter tyres on the 700c rim but you'd probably run into clearance issues.

    So, if you've got a narrow tyre, get a fatter one rather than change wheels - after all it's only a £500 bike so changing wheels doesn't seem particularly economical.
    Bike lover and part-time cyclist.