How To Go Solo

So, for reasons best known to yourself, you've decided to take all but one of the gears off your mountain bike (one of the more lively phone conversations I've had in my life was explaining to my parents what I was doing to the mountain bike they'd helped me buy not eight months previously). How do you go about doing it?

There are various sites about that'll guide you through the process, though they're all a few years old now (which was the principle inspiration to setting up this blog). The two most informative I found are Triangle Mountain Bike and Sheldon Brown's bit on conversions. I disagree with some of the things said on both sites, most notably Sheldon's recommendation that you don't use rear disc brakes which I think would be a fairly courageous choice for technical singletrack use, especially in the wet.

The simplest, but most expensive way to ride single speed is just to buy yourself a dedicated single speed bike. OnOne do an excellent set of "rolling chassis" where they sell you a frame, a fork, and some wheels - leaving brake and saddle choice to you. Alternatively Genesis do a solid range of single speed bikes. Fortunately for all of us, as mountain biking has grown enormously in popularity over the last decade, more and more companies have been able to accommodate the outer fringes of the sport more and more (does anyone else dimly recall the nineties when one bike did everything, and the world championship downhillers wore lycra and sky diving goggles?) so gone are the days when getting a single speed mountain bike meant investing in a track frame, and bunch of rosary beads to make sure the thing didn't come apart on shaky descents.

But let's assume you're a bit more like me, and can't really justify buying a new bike, what do you have to do? Firstly, you have to take everything off. This means the front chainrings (keep the middle one, you'll need that in a bit - provided it's not too worn), derailleurs, cables, and rear cassette. Then take a look at your dropouts. Sheldon has a handy pictorial guide to them - but if you've got anything other than horizontal dropouts (we'll debate later whether we can legitimately call them "dropouts"), you're going to need a chain tensioner.

Chain tensioners come in all sorts of weird shapes and sizes, in a few weeks I'm going to do a more comprehensive article focussing on them, as I'm currently undertaking a long term test of a number of different designs. But as a beginner converter, you've got two realistic options: keep your rear derailleur, or buy a single speed conversion kit. Keeping your rear derailleur will add a little weight, but will be incredibly dependable, and maintain near perfect chain tension all the time. The research man-hours that big bike companies (probably either Shimano or SRAM in this case) can put into their components far outstrips that that small single speed companies can put in, producing components that are usually fairly bomb-proof. The other advantage to keeping your rear derailleur is that if you do horrify yourself with the monstrosity you turn your pride and joy into, you can always quickly reverse the changes and pretend nothing happened.

As for dedicated single speed conversion kits, the only one I can recommend (and I can't recommend it highly enough) is the kit by DMR. It comes with everything you need, a sprocket of a sensible size, spacers for your freehub body, and a chain tensioner. I raced and rode perfectly happily on this for a year with no major issues.

Finally, there is the final thorny issue of gear ratios. The simplest method to choose is to go with what you've got. Slap your old middle ring on its own on your cranks (NOTE - you will need to buy single speed chainring bolts, your old triple crankset ones will be too long. They're sometimes advertised as BMX bolts), and purchase yourself a rear sprocket. Depending on where you live, you'll want different sizes. In somewhere pretty flat, a 2:1 ratio should be fine (take a standard 32 tooth front ring, and pair it with a 16 tooth sprocket). But somewhere more hilly you might want to think about using an 18 or even 19 tooth rear sprocket. After you've ridden on a bunch of different terrains, you'll almost inevitably wind up with an old jam jar full of different size cogs (I even have a massive 25 tooth one I tore out of a cassette to race BUCS on last year). Talking about gear ratios though is a brilliant way to start an argument between SingleSpeeders. In reality, what's comfortable for you depends on a massive number of things like crank length, natural cadence, and type of terrain you're riding over. My advice is to start with 2:1, then buy a couple of other sizes so you're catered for most problems (sprockets are dead cheap).