Singlespeed & Fixed Gear - threadon freewheel mod

Hi

I'm new to this list...

Have just begun modifying a 20yr old MTB to single speed. Could never stand up on the peddles and get off the seat with the original configuration so decided to pull the bike apart. Have learned a lot in the past month - mainly from Sheldon.

What I've done is remove the smallest sprocket from the freewheeling Shimano thread on and discarded the bigger sprockets. I've then put the smallest sprocket back on but reversed it so that it gives me an extra 5 millimetres toward the centre of the frame. This seems to give the chainline a straight pull from the chainwheel to the rear sprocket. I haven't used a chain tensioner as things just seemed to fall into place. Emboldend by this first success, I have done a similar job on a step through frame for my partner (lady friend).

The dropouts are not vertical but are inclined forward. I've used a big spanner to tighten the axle bolts and that works fine; but I haven't really pushed things. For example I haven't risen from the seat going up a steep hill. (When I was eight years old I dropped on the front bar and haven't forgotten the experience.)

Anybody know of an way of locking the back axle in position?? I'm interested in do it yourself fixes.

Cheers

Greg

Originally posted by winterflood

Anybody know of an way of locking the back axle in position?? I'm interested in do it yourself fixes.

Cheers

Greg If you've got a bolt on axle (sounds like it) just tighten up and you'll be fine. I've got a fixed gear that has the same type drop outs and the thing doesn't budge, even mashing up the steep hills around here.

I would recommend getting some track nuts with built in washers so you don't tear up the drop outs and you can tighten things up better. Sheldon has them for around $10.

crown/serrated washers do the trick for me, and i use QR's too

You should be ok,but beware of using QR on a fixie,thats asking for trouble.Tensioner isnt mandatory on singlespeeds provided you can get chain tight enough stay on,what is does do is limit your gearing options.

Thanks for the help. Dropped into the LBS here in Alice Springs yesterday to find that they have several devices for sale which, in effect, pull the axle back by locking onto the rounded rear end of the frame behind the dropout. Hadn't seen those before, but given the advice above I probably don't need them.

Greg

Ya those are modified versions of the axle/chain tension adjusters found on BMX and SS mtb's.They work quite well.

Thanks. I'll give it a go without them...and wait until the chain drops off!! Then I'll investigate.

Greg