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MTB chainset on a ROAD bike ?

MaK-71MaK-71 Posts: 38
edited September 2012 in Workshop
Mornin :?:

Its winter bike time of year and I have been doing some pondering.
I have got an old school steel 531c racer from back in the day and I am going to turn it into my new winter hack but need to change the gearing.
Currently its 42-52 with a 6 speed cassette 12-23! (How I ever turned that as a school boy is beyond me!)
I am looking at either buying a compact 34-50 road chainset or possibly going even smaller to a MTB chainset and taking off the small 22 ring, it would then be something like a 32-44 for maximum winter leg twiddle factor. Its running a square taper BB so was hoping to go square taper as not bothered about the weight factor.
Has anyone ever had any experience doing this?
:?
Cheers Makka

Posts

  • Yeah, I converted a knackered old steel road double to an MTB triple once. It was great for about two months, then some b*strd stole it. It was that good!

    First problem, 6-speed chain is wider than 8, 9, and 10 speed, it may ghost shift and jam if you run it on a modern crankset - I have no experience.

    Second problem: an MTB triple is wider than a road double, so you could end up with a bad chainline on the big ring. A shorter BB axle may get you back to the original chainline, but you can only do this if you have clearance with the drive-side chainstay. Another option could be to use the two inner rings of a road triple?

    Third problem: shifting. If you just move the existing front derailleur down a bit, it will probably work but it will need constant trimming. 50t to 46t was ok for me, but 52 to 44 is a big jump. So you may be looking at a new MTB front derailleur.

    You do plan to stay with your old-skool friction shifters, right?
  • drlodgedrlodge Posts: 4,825
    I don't think you'll have a problem really, if you go with a compact 34-50. You can use an 8 speed chain OK on 6/7 speed cassette. A shimano 2300 chainset, or cheaper FSA square taper will fit, but you will need to lower the front derailleur and set it up carefully.

    You might also be able to swap the rear cassette, what kind of cassette and fitting is it...Shimano splined freehub?
    WyndyMilla Massive Attack | Rourke 953 | Condor Italia 531 Pro | Boardman CX Pro | DT Swiss RR440 Tubeless Wheels
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  • keef66keef66 Posts: 13,123
    You sure it's a cassette and not a freewheel??
  • Thanks for the replies guys,
    It looks like I might have to go down the road compact chainset route.
    I thought about changing the rear cassette ratios but its an early Shimano 600 uniglide (pre Hyperglide).
    The freewheel could possibly be changed or modified but I recon a cheap sq taper compact chainset with a narrower chain might be the way to go.

    Cheers Makka :wink:
  • keef66keef66 Posts: 13,123
    If you needed an extra twiddle factor without messing with the back you can often pick up cyclo-cross chainsets cheaply. 46 / 36 type of thing?

    Might struggle to find a square taper one though
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