Converting to a single gear set-up is a great way to reduce maintenance, concentrate on your riding skills and build up your strength and leg speed over winter.
Whip out the wheel
As with most workshop tasks, ideally you should put the bike into your workstand. If you don’t have one then you can get away with the old favorite upside-down bike technique, but be prepared to do some scrabbling round on your knees. So first up, spin it over and remove the rear wheel.
Grab your chainlink tool and remove the chain. If you have a Shimano chain, then push the pin all the way through any others and make sure the pin doesn’t get pushed all the way out. If you have a snap link, then just pull it apart.
Set the cassette aside
The cassette is the next to go. It can be pretty difficult to get the lockring cracked open, but good technique can make life easier. Check out our top tip guide for safely removing (and servicing, for that matter) particularly stubborn cassettes without hurting yourself on p32 of this very magazine.
Now remove the right-hand pedal from the crank. With the bike upside down, put your foot on the saddle and, with the crank in the forward position and the spanner or Allen key facing back, pull up. This gives much more power than pushing down, and is safer. Once released, fully unscrew the pedal.
Remove – and refit – the right-hand crank. For Shimano Hollowtech or FSA Mega-Exo cranks, undo both 5mm Allen bolts in the left-hand crank, remove the retainer using the correct Shimano tool or an Allen key on a Mega-Exo, remove the left crank and draw the right crank out complete with axle out. To refit, push the crank and axle through, re-mount the left crank, tighten the cap to 0.5Nm and the pinch bolts to 13Nm.
Remove – and refit – Shimano Octalink/square taper or ISIS right-hand crank by undoing the 8mm bolt. Some systems have single key release, and the crank will come off as you remove the bolt. If not, screw in the relevant crank extractor tool (ask your bike shop if unsure) and whip the crank off. Refit the crank by sliding the crank onto the splines and screwing the bolt in to a torque of 42Nm.
Remove – and refit – Race Face X-Type cranks by unscrewing the 8mm self-extracting bolt in the drive-side crank arm all the way before removing the crank. To refit, align the crank and screw the bolt in until it bottoms out into its stop position. This is a hard stop, and you’ll be able to feel when it reaches it.
Fit single chainring
Some Shimano chainsets need a special tool to hold the nut part on the inside of the outer two chainrings. If not, use the relevant Allen or Torx keys to remove the nuts and bolts. Once off, remove the inner chainring by removing the bolts. Now fit your new chainring into the middle position and bolt it using your single chainring bolt set. Tighten it to 9.5Nm for steel, 7.5Nm for aluminium. Refit the crank to the bike.
Shift those shifters
Time to remove the now redundant derailleurs. If you have top-tube routed cables, you can leave them attached to the shifters. This helps if or when you decide to convert back. Unhook the cable outers from the slotted guides. Undo the rear mech from the dropout and remove the front mech from the frame. Thread them through the frame or brake hoses towards the shifters.
Get a grip
Hopefully you’ve got lock-on grips, otherwise you’re now going to need new ones. Remove the grips from the bars. If your shifters are outboard of your brake levers, remove them. If not, measure the distance of the brake levers’ clamps from the end of the bars. Remove the brake levers and shifters, and replace the brake levers in their pre-measured position. Slap the lock-on grips back on, or a new pair if needed.
Space out your sprocket
Grab the back wheel and give the freehub body a clean, including the internal threads where the lockring fits. Smear a light coating of Teflon grease over the body. Now fit the spacers and sprocket from your conversion kit, start with the thickest first, then the sprocket, then the thinner two. Thread the lockring in hand tight.
Line up the chain
Put the wheel into the bike and get your new chain. Lie the chain across the sprocket and chainring, and look down it from behind. The sprocket and chainring need to be as in-line as possible, and the chain will help you gauge this. If it doesn’t look right, swap the spacers around until you get it as close as possible. Once this is achieved, tighten the cassette lockring to 40Nm with your torque wrench.
Shorten chain and fit
You want the chain to be as short as possible. Fit the chain around the chainring and sprocket, then bring the two ends together. Work out how many links you can remove, remembering that the chain must have an outer plate-end one end and inner plate-end the other to rejoin it. Use your chain rivet tool to rejoin the chain, ensuring the join isn’t stiff.
Mount chain device
We’ve used a DMR Simple Tension Seeker here, because we’ve found it to be the most universally compatible. Attach the figure-of-eight adapter to the dropout by sliding it onto the quick-release and then locking it down against the frame. Then bolt the tensioner arm onto the adapter and dropout using the bolts in the kit. Leave it loose for now. For other systems, follow their enclosed instructions.
Push the arm and roller up against the chain so the chain is under mild tension. If you apply too much pressure to the chain it’ll be noisy and inefficient, too little and you risk the chain falling off. About 5mm of free play up and down in the center between chainring and sprocket is about right. Lock it down into place, tightening the bolt into the gear hanger to 9Nm, and the bolt into the adapter to 8Nm.
Gear up for one gear
Spin the bike the right way up, screw your pedal in to the crank and tighten it to a torque of 35Nm. Get your brake levers adjusted to your preference, tightening them to 5Nm. Now hop on the bike and go for a quick spin around the block to make sure everything is working 100 %. Welcome to the world of simple, low maintenance singlespeed cycling.