Riding singlespeed means no complications with gears. You can’t ride too quickly, because you run out of faster gears straight away and there’s a limit to how fast your feet can spin around. If you have gears, you’re tempted to shift up a gear and go faster. But with only one, you are forced to ride round calmly and arrive at places in your own good time, rather than hot and bothered, having just beaten your own personal best time for the journey for no apparent reason whatsoever.
Once a niche part of cycling, you can now buy singlespeed bikes off the shelf in a bike shop – they are a common sight on the roads. You can also make one out of your normal, geared bike. This has its advantages as a maintenance
procedure – it mainly consists of taking parts off your bike and stashing them away to be recycled in a future project.
Shifters, cables, and derailleurs can all come off. Your chainset too. If it has removable chainrings, get rid of all but one of them. The chainring bolts that hold everything together will be too long to hold your now single chainring securely, but luckily they’re available in a shorter size too. They’re called single chainring bolts and you’ll need as many as you have arms on your chainset. If your chainrings aren’t removeable, you can either just continue to use the chainring you have, ignoring the chainrings you’re not using, or replace it with a single chainring.
Deciding on your gear ratio can be a bit tricky. It’s a case of trial and error and working out what feels good to you. You need a gear that’s low enough to get you up the steepest hill you normally climb without busting a gut. It depends on a combination of how fit you are and how flat the area you live in is. Once you’ve got rid of all the other kit, you need to concentrate on the back end of the bike. If you’re converting from a geared bike, you have several potential solutions available to you.
- Simply leave the cassette on the bike, choose a gear that suits you and leave the chain running over that sprocket. With no shifters, the chain will stay put. This is the simplest solution and a good idea on a temporary basis, giving you a chance to experiment with gear ratios.
- Replace your cassette sprockets with a single sprocket and spacers to make up the gap. The DIY version is to use one of the sprockets you’ve already got and make up spacers from plastic plumbing pipe, cassette spacing washers or whatever else you can come up with. Make sure the washers take up all the available space and clamp it all on with your lockring. There are commercial versions of this such as the Gusset converter.
- If your wheel is on its last legs, replace it with one that has a purpose-built singlespeed hub – those made by Surly are great value, but for bling, check out Phil Wood singlespeed hubs.
Light, cheap and, above all, simple
The shape of your rear dropout determines what you do next. Look at the dropout and work out what direction the wheel moves in when you take it off the bike. If it moves downwards, you have a vertical dropout. If the wheel moves forwards (or even backwards), you’re in luck as this is the easiest to deal with.
Vertical dropouts: these mean you need a gadget to take up the chain slack, a bit like a derailleur but without the guide jockey since you don’t need to move the chain sideways. These are called chain tensioners or singulators – although you can use a normal rear derailleur if you’re prepared to be a little bit inventive in getting it to hang exactly under your chosen sprocket.
Horizontal dropouts: these don’t need to be precisely horizontal – sloping is fine as long as you can move the wheel back and forth in the frame. This allows you precise control over the chain tension. Pull the wheel back until the chain has about 1.5cm (1⁄2 in) of movement at its slackest point. Tighten wheel nuts firmly.
“Once you’ve got rid of all the other kit, you need to concentrate on the back end of the bike”
Source : BIKE MAINTENANCE TIPS, TRICKS & TECHNIQUES
See also bike maintenance tips, tricks and techniques “Mountain bike singlespeeds: hubs, chainline, and appropriate gears”