The Greatest Single Speed Mech Bodge

[Krisboats]

This bodge will leave you with an easily adjustable and robust method of getting your rear mech in exactly the place you want it. It provides a more reliable and easy to use way of adjusting the mech alignment and allows greater alignment than the traditional cable/spoke clamping bodge.

Right then, first off you'll need your rear mech, a drill (with 5mm drill bit), a small screwdriver, M5 bolt (5mm allen stem bolt will be adequate) and a 5mm allen key.

The theory: Basically all that happens is your putting a bigger bolt in to allow for a greater adjustment where the high/low adjustment screws are. The bolt will press against the small triangular tab effectively holding your mech in place. Note where the triangular tab is and be sure to keep it out of the way when drilling it later.

Firstly we'll need to remove the high and low adjustment screws, so get the screwdriver and start undoing them.

Then you need to remove the little black piece of plastic that surrounds them, again using the screwdriver, just pry the plastic out like so.

Now this is out of the way you'll have a clear area to start the drill going into. Get your drill and 5mm drill bit and try and align it up fairly straight. You're going to need to drill all the way through the existing hole to allow you to cut a bigger thread into it with the bolt. MAKE SURE YOU DON'T DRILL THROUGH THE TRIANGULAR TAB OR THE SPRING!

Right now we've got the hole the right size its time to cut a thread into it. If you have a thread cutter then you can use that but its easy enough to cut a thread into it using the bolt itself. You'll have to get some real force pressing onto the bolt though for the initial few threads. After the first few threads have been cut into the mech you wont have to press so hard, but the twisting will get increasingly harder. To ease this, back the bolt out and put a drop of oil into the hole and continue with the thread cutting, eventually you'll get the bolt all the way through. Its also sometimes easier if you make the entrance of the hole slightly bigger... this can be done by either using a 5.5/6mm drill bit and just drilling the entrance a bit wider, or by using the 5mm drill bit and wiggling it around in the hole a bit.

Once the bolt is fully in spend a few minutes winding it in and loosening it off, dropping some oil in there every now and again to smoothen the threads off. After a few minutes the bolt will be fully twistable by hand should you need to adjust it mid-ride.

And there you have it, you're left with an effective and highly adjustable single speed tensioner that looks alright and will have enough strength to properly tension your chain.

Further Bodging

Now if your skilled with an angle grinder you can grind off the tabs that used to be needed to make the mech slightly lighter and to make it look more streamlined. If you also remove the tensioning spring from the breakaway bolt area (known as locking the mech out) you can position the mech closer to the frame, removing the need for the first jockey wheel, with this jockey wheel gone it also allows you to run a wider chain, which is great for single speed users.

[downhill_rob2@hotmail.com]

Horazontal (sp?) drop outs

[Ashley Smith]

just to add, for an m5 bolt (cap head) you would use a 4.2mm drill bit, as 5mm would be too big really and the thrwad would strip quite easily

good bodge though

thats the same as i have done to mine

ash

[Dan-Walker]

I done a mech bodge today with a mate down my local bikeshop, turned out pretty well infact, works really well. Cut loads of metal off that i did not need, here is a pic........

Edited August 17, 2006 by identitijudge05

[Netherking]

I done a mech bodge today with a mate down my local bikeshop, turned out pretty well infact, works really well. Cut loads of metal off that i did not need, here is a pic........

brilliant, spent agers looking for this

[Krisboats]

What?! Almost exactly a year ago that i did that bodge... and its still going strong today

Though i am now building a new tensioner :$

[Tomm]

I never saw your bodge a year ago... But you can just replace the existing limit screws with longer ones of the same thread size. Much simpler than your method? Unless I missed something?

[BIG Drew]

Yeah, that is what I did until the threads stripped and the bolt just slid back out. Now I just have a cable tie holding it in position and it is working fine. It is just as east to adjust as well:)

[Krisboats]

I never saw your bodge a year ago... But you can just replace the existing limit screws with longer ones of the same thread size. Much simpler than your method? Unless I missed something?

I wanted a big fat screw that was 5mm same as all my other allen key bolts

[Muel]

If you swap all the bolts on your bike for ones with a 5mm head, you only have to carry one allen key.