The Single Speed Guide

I remember when I was trying to put together my first single-speed. Being the guy I am, I HAD to know everything about them. Gearing, chain tension options, do I need different wheels? I spent hours scouring the net and consulting everyone who ever heard of one. Like most things in life everyone has a different opinion, and making sense out of all the differing information was difficult to say the least. I created this guide to help others make sense of the sometimes overwhelming amount of information regarding single speeds. I want to keep this guide open to additions, so if any SS aficionados have any tips or corrections please leave a comment. Any questions are more than welcome as well.

What is it and why should I Have One?
The single speed, commonly abbreviated SS, refers to a bike with only one gear or speed. SS’s exist in many different forms including mountain bikes, road bikes and BMX. There are also fixed gear bikes that have one speed but no freewheel: As long as your bike moves, your pedals move, so no coasting. These are referred to exclusively as fixed gear bikes, SS’s always have a freewheel for coasting. Single speed bikes, especially in the mountain bike world, have been steadily gaining popularity over the years, and for good reason. This guide is specific to single speed mountain bikes, although a lot of the information can be useful for road, BMX or even fixed gear.

The big draw for single-speeds is the simplicity. In a world of increasing complication SS’s mean two brake levers and pedals: There are no shifters or derailleurs to master, adjust and maintain, just jump on and go. They offer a retro feel, like you’re going back to a simpler time, getting back to basics. Besides that they are great for training: Spend a few weeks doing hill sprints, and deep sand and tough climbs will come easy. Another thing SS’s teach you is how to use the trail. With our full suspension bikes and infinite gears we like to plow through and over objects trying to conquer the next trail. Trust me, I’m one for the monster truck mentality, but finesse is good too at times. Singles will quickly teach you a new definition of momentum. Small dips and embankments that you used to classify as obstacles become tools to increase your momentum. You learn to become one with the trail and use every twist and turn to help you move faster and expend less energy. When you jump back on your geared bike you will notice a huge increase in your efficiency.

Besides training and simplicity a new culture has evolved around SS’s. Today many race circuits offer single speed categories and many websites are dedicated to the phenomenon. Perhaps the best thing about single speeds is they can be built from carbon and Ti, or created by transforming that old backup mountain bike you never ride. Either way try it! It doesn’t cost a lot to get a bike built up, and it offers a completely different experience.

Chain Tension
On a standard bike the rear derailleur uses a system of springs and pulleys to keep the chain tensioned. Chain tension is important so your chain fully engages with the cogs. Without proper tension your chain will slip and skip over teeth. Since you won’t have a derailleur on your single speed, you need to find another way to keep your chain tensioned.

Dropouts
If you do not already know, dropouts are the parts on your frame that the axles on your wheels sit in. There are three major types of rear dropouts, standard, track and horizontal. The standard dropout is the most common and means you will need to use a tensioner or something else to keep chain tension. If you have the angled style horizontal dropouts, or track (rear facing horizontal drop outs), you can tension your chain simply by pulling the wheel tight before closing your quick release. I have heard various opinions on the quick release’s ability to hold chain tension, so if you find that your wheel slowly drifts forward and you are using horizontal dropouts, buy a BMX style chain tensioner/tug nut (not the derailleur type, this tensioner mounts inside of the dropout and has a setscrew to keep the wheel’s axle from moving forward). 

Perfecting Chain Length
If you have standard dropouts one of the cheapest and most reliable ways to keep chain tension is to get your chain length perfect. One way to do this is to buy a couple cogs with different teeth amounts. Try each cog until you get a combo that works. You want a new chain to be pretty tight. You should be able to feel the links when you pedal. After a little riding it will stretch to the perfect length. If you are lucky the chain might fit perfectly right away. The other alternative is to buy something called a half link to fine tune the chain length. After trying a few of the other options, this is what I do on my current SS.

The Chain Tensioner
One of the easiest ways to keep tension with standard dropouts is to use a chain tensioner. The chain tensioner emulates a rear derailleur so you need to have a hanger that is threaded for a rear derailleur. This is a great way to convert an old geared bike into a single speed! There are many kits online including some budget kits from Performance Bike that include cogs and spacers, but I’ll get into that more in a bit. I’ve personally used a few of these and the “you get what you pay for” adage applies here more than ever. The chain tensioner is a quick and easy solution, but through my experiences, even the best ones slip at times.

Going Eccentric
Another option is to get a frame with an eccentric bottom bracket or buy an eccentric rear hub. An eccentric allows you to change the tension on the chain through a center that rotates around an outer shell. Loosen the set screw; rotate it to get proper tension, than tighten the set screws. The downside is the cost and availability. Eccentric hubs are not cheap, and finding the frame you want that is built with an eccentric bottom bracket shell can be difficult. Nevertheless if you have found the perfect frame and want the easiest most reliable way to get the perfect tension with any gear combo, an eccentric hub is the perfect solution.

Gears
The standard gearing for a single speed is 32-16: That is a 32 tooth chainring in the front and a 16 tooth cog in the rear. A cog with fewer teeth in the back will make pedaling more difficult, just like switching to a higher gear, while more teeth will make the ride easier. For the front gearing is reversed, so more teeth means tougher, less teeth means easier. Use a 32-18 combo if you plan on riding more hills or try 32-14 for high speed single-track. If you want to get technical this calculator from Sheldon Brown will calculate gear inches, gain ratio or speed at a certain RPM. I won’t go into detail on it, but the standard 32-16 combo offers 52 gear inches.

For your front chainring you can either buy a SS crankset or take the little ring and big ring off of an existing crankset. Usually the middle ring is 32 teeth; sometimes you’ll find a 34, in which case use a 17 tooth cog in the rear to get the same ratio as a 32-16. For the rear you need a cog and spacers. The spacers let you space the cog on the hub so it is directly in line with the chainring up front. This is called chain line. A crooked chain line means power loss and excess wear and tear on your gears. There is no secret method that I know of to do this, just eyeball and adjust until the chain looks straight. As I said before you can buy kits that include both cogs and spacers for a few bucks, but if you want something more durable stay away from these sets. Chris King makes aluminum and stainless cogs in virtually every tooth range you could ever want. You can order them directly from Chris King’s website. You can find spacer and gusset kits all around the web, just do a Google search.

I hope this helps answer any of your questions and inspire your curiosity. Happy Trails!

Related Posts

• October 20, 2008 -- Mountain Bike History 101 and the Single Speed
• July 13, 2008 -- First Ride On My Fully Rigid Singular Swift SS Mountain Bike