Singlespeed & Fixed Gear - moutain bike track frame crankset size inquiry

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skinnyboy
07-29-08, 10:46 PM
Do mountain track frames usually run 110mm bcd crankset, rather than 130mm bcd?
How big of a chainring I can use? Is it usually smaller for rear triangle clearance?
just curious. thanks.

FlatFender
07-30-08, 12:13 AM
Do mountain track frames usually run 110mm bcd crankset, rather than 130mm bcd?
How big of a chainring I can use? Is it usually smaller for rear triangle clearance?
just curious. thanks.

MTBs use a few different BCDs. 104 is pretty popular.
They usually run a 42t large ring. you could probably go a little large though, on the outside.
skinnyboy
07-30-08, 12:41 AM
actually does it really matter wheter it is 104 or 110 or 130? I think as long as there is clearance
between the chainring and the seatstay, it should be fine. That means the BB spindle length needs to
be longer to accomodate bigger ring.

Saddle Up
07-30-08, 08:58 AM
Mountain track frame??
robcycle
08-03-08, 04:02 PM
They usually run a 42t large ring.
44.

On a geared mtb (where a 44t ring would be run), the big ring is run on the outside space on the spider. This would not make for a good chainline, unless you were going to respace the axle or use a cassette wheel with spacers. A 44t (or larger) ring might fit in the middle position and allow a conventional chainline, but it would depend on the chainstays. A single-speed mtb would typically run a ratio near 2:1, generally 32/16. This allows them to climb big hills. Clearance isn't always planned in.

-Rob.