Can I convert?

[Batfink]

Hi
Great wee forum and thanks for the info and links so far. Riding a
fixie has been something I have been thinking about for some time. I
currently commute in 09 central via a ferry ride from the Shore. My
current velocipede is a GT Zum 3.0. basically an MTB (quality frame)
set up for the urban environment. But I hate all the clutter and I
just love pure riding. I have just returned from 5 months living in
Ireland where I was able to commute a 14km round trip via city centre
and river bank - brilliant. I have come home and cant wait to ride
again but I want to strip the ZUM back to its bare bones.
So here are my questions.....
Can I convert an MTB frame to a fixie?
What would be the best gear ratio for a beginner?
Am I mad?

[martinv]

Hi Batfink,

Sure you can convert a mountain bike frame to fixed gear. Perhaps the
biggest challenge will be getting the chain-line right. See the late
Sheldon Brown's website for details on that.

One thing worth considering though is does the frame have near
horizontal dropouts at the rear? If it does then there is much more
scope for adjusting tension on the chain (good). If instead it has
vertical dropouts, then you'll have less adjustment - possibly none,
making your choice of sprockets and chain rings critical. I converted
a Vitus frame with vertical dropouts to fixed gear (see the article on
building a rear wheel on this website), but as the chain wears there
will be no way to take up the slack as the rear wheel cannot be moved
forward/back.

Somewhere between 65"-75" for a gear size seems popular for use on the
flat. I don't know what size tires, sprockets and chain-rings you
have, but if you look at the First Gear software I wrote (trials of
the software are free), you will be able to play till your heart's
content finding out what combination of all these will lead you to the
right sized gear, and which will fit well on your frame (allowing as
much adjustment as possible as the chain wears).

Regards,

-Martin