Q factor: Shimano vs Suntour? vs M-ighty?

bigflangesmallsprocket
bigflangesmallsprocket Posts: 2,443
edited September 2010 in The workshop
I did post this subject in the mtb section, as the kit is mostly mtb based, but it seems mtb'ers care not a jot for Q factors. So I'm posting here. Roadies probably arent interested in Q factors for mtb kit!

I've just purchased a Carrera Subway Ltd Edition and even though it's the mens small (18"), it still has 175 cranks! Well I'm a skinny built shortarse so I'm not keen on the Q factor nor the length. I'm looking at budget 170mm replacements:

http://www.halfords.com/webapp/wcs/stor ... yId_165545

http://www.halfords.com/webapp/wcs/stor ... yId_165545

The above look look interesting as they look as if the arms don't flare out so much, so a smaller 'q' factor? Plus of course, both are sold by Halfords as replacements so should not void my warranty.

I've also seen these in 170's:

http://cgi.ebay.co.uk/SR-Suntour-XCM-V2 ... 335f6fe7ed

http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... K:MEWAX:IT

which aren't sold by Halfords, but do look interesting nevertheless. I'd be very grateful if anyone could compare Q factors for me!

Jam butties, officially endorsed by the Diddymen Olympic Squad

Comments

  • I'd be wary of how crank arms look, it is really best to trial-fit them.
    Also, you can squeeze 5mm from the position of your cleats.

    There should be a K-Factor for how far your knees stick out. I do enjoy lampooning newbies on road bikes whose knees stick out further than their elbows :D
    FCN16 - 1970 BSA Wayfarer

    FCN4 - Fixie Inc
  • I did pop into Halfords today to have a look. Youre right, it's pretty hard to compare chainsets just from a visual, especially if you don't know what bottom bracket is fitted on the example.

    For this bike I don't intend to use pedals that require cleats: I have slightly odd leg lengths and I've had to add a spacer under one cleat for use with my road bike. This means that when I'm walking I do a pretty good impersonation of having a noisy limp and it's not an especially comfortable experience.

    Reading up some, and looking at my own bike, theres a tendency toward wider than necessary chainlines on mtb sytle bikes, so simply getting a bottom bracket to reduce the chainline back down could be a good and relatively cheap start, though I still want shorter cranks really.

    Jam butties, officially endorsed by the Diddymen Olympic Squad
  • nicklouse
    nicklouse Posts: 50,675
    as it is Square taper cranks a change of BB axle length would be the easiest option, but watch out for rings fouling on the chain stays.

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