Step-By-Step Single Speed Mountain Bike Build
Simple, pure, and challenging are the three words I would choose to describe single speed mountain biking. Single speed bikes represent a different type of MTB, no shifting, no derailleur cables or adjustments. Why do people shoose single speed, if it is a harder, slower and less advantageous style of ride? Well, maybe single speed presents a new chalenge, maybe it's a way to save on maintenance, tell the biking companies we don't need your expensive or gimmicky producs or perhaps, just perhaps it brings us back to the days of grade school BMX riding and the simple pure enjoyment of the sport.
This hub is a step by step process to build a hardtail singlespeed bike with very little cost, of course, you can always spend more better options, which I'll recommend here as well. For me part of the fun is buying as little premade parts as possible, which give a better sense of accomplishment.
The idea of this hub is that if you are like me and love to tinker with bikes, have a few boxes of old parts, and a couple of bucks, building and riding a single speed can be a blast..
First step: Get a bike!
Ok, so when I decided to build this I promised myself that I was going to do this cheaply. I had two options, an old GT Avalanche frame lying on my garage floor, or an old Specialized Stumpjumper Frame (complete with a set of blow out old Rock Shox Judy forks) I ran across at a second hand bike store for 5$. I opted for the latter. Really any bike will work and you don't have to worry much about the overall set of components, you aren't going to acutally use the shifters, ect.
Two things to consider:
A hardtail is better! Single speed riding relies a lot on extra pedal effort instead of dropping gears to maintain rpms. Thus, a hardtal will minimize 'bob' and help you get up those hills. This is one reason you see a lot of single speeders even rolling with a fully rigid frame.
Second: Its cheaper to get a chain ring than a new crankset. Seems obvious, and many purists will argue that a true single speed cannot be made from a triple ring crankset. I beg to differ on this and used a triple ring crankset for this build.
Step Two: Get your supplies
You'll need most likely :
A Crank puller (maybe, but necessary)
A Chain Breaker Tool
Basic tools: Screwdrivers Pliers, adjustable wrenches
A set of Allen Keys or Park Tool Set
A pipe cutter
Lockring removal tool or needle nose pliers
An old bike chain or a chain whip
A section of 1 1/4" PVC pipe and/or spacers from the rear casette (two sets of rear casette spacers fwill make one singlespeed bike) ...or.... a single speed kit with spacers which you can get online for about 25$
A new chain (single speed chain if you are putting on single speed sprockets)
Front Chainring (usually 29, 32 36 teeth)
Rear Sprocket (usually a 2:1 ratio so a 16 tooth sprocket for a 32 tooth front chainring)
Rear Derailleur or a chain tensioner
New Brake cables, ect if they are old and worn
Step Three: Strip Your bike down to the basics.
Ok, this is a fun part. Take off everything in the drivetrain and the tires. Inspect all the parts, clean the bike and then throw out the out shifters, cables and housing. Yell 'Good riddance' as yo do it, it'll make you feel good.
Take the rear wheel and remove the casette. You'll need a chain whip and a lockring removal tool to do this......or you can take an old chain and secure it to a wrench and use a pair of needle nose pliers to hold the lock ring (See Photos).
You can remove the crankset using a crank puller. If you have bolt secured chainrings you might not have to remove the crankset. In theory, the large chainring can bolt off and come right out. The small one can be ...ahem...removed....by cutting it off, or breaking it by some bending with two pairs of pliers, which is actually quite easy with aluminum chainrings.
However, you may have to (or want to) remove the entire crankset if your middle chainring was as worn as mine (photo) or if the the chainrings are riveted together. You can try to pry apart riveted cranks, but I have never had any success with that
A crank puller is a cheap tool that will run you aroun 15 to 20 dollars and is necessary for the work. Its a great investment for your toolbox, and if you are a bike tinkering fool like myself, will serve you for years down the road. You can try to hammer the cranks off but it usually doesn't work.
Once the crank is removed you can install your new chainring (it might be a bit loose, keep reading and I'll explain that) or crankset fairly easily.
Step 4: The Chainline
First, you need to put the front chainring on the crankset. If you are using a three piece crankset, you'll find the bolts are too long for just one chain ring to be on the bike. My solution was to use vice grips and just break the bolt holes off the large chainring and use them as spacers (totally high class setup- see photo). ....or you could buy some washers at the hardware store, or a set of BMX bolts, which will be the correct length for using one chainring. Just make sure the front chainring is good and secure before trying to determine a chainline.
Put the rear sprocket on the hub and put the rear wheel on the bike. Using a piece of chain find where it must sit to make a nice straight chainline. Mark the location of the sprocket using chalk or a pencil on the hub. Now you will know exactly how much spacer you need on each side.
I used several casette spacers for the inside and cut a piece of pvc for the outside spacer. You could also use casette spacers for the outside as well (which is recommened) however, I only had enough for one side when I built this however. The PVC fit snugly ( I had to use a piece of wood to tap it on) and was a perfect fit once I tightened the lockring on the hub. Make sure you cut the PVC so the lockring puts pressure on it, just a hair longer than you would think and make sure its a nice straight cut (not like the one in the photo). This keeps the sprocket straight and secure on the bike.
Five: The Chain / Rear Deraileur / Tensioner
You don't need an expensive chain tensioner for a single speed. I used an old Shimano XT derailleur for my bike.
Note: I tried a SRAM derailleur but the housing was not wide enough to allow for the single speed masterlink to pass through. So check and make sure a single speed cain will fit through. If it won't you can add a washer to the inside of both of the pulleys of your derailleur to allow the chain to fit through easily.
Now youmust consider that a single speed chain won't run smoothly on regular chainrings / sprockets. There isn't an issue with just using a standard chain with standard drivetrain components but singlespeed specific components are better designed to keep the chain from slipping off the teeth since they have no ramps or pins on them. The components are pretty cheap, I found my single speed chainring for 15 dollars, the chain for 10 and the sprocket was about 5 bucks so 30 dollars for the entire drivetrain, which is about what a nice standard chain would cost you.
I used a small piece of cable to line up the rear derailleur on the bike (photo) and voila, good to go. I cut my chain so that it was shorter than a normal mountain bike, you want to have high tension to hold it in place. Then I used the position screw on the derailleur to add a bit more tension. It works perfectly, and I almost never throw the chain, even without a front chainguide.
Really thats all there is too it. Slam on whatever components you want, I'll be putting on the single speed chainring when it arives bike in the mail, the photos still show the old one from the and also will be searching for a front disc brake and a specialzed sharktooth (If you have one let me know!) to finish the bike.
Two final things to think of before you start the project. You will want to consider getting a front chainguide. This will prevent the chain from popping off in rough spots or it you toss up a stick, ect. You will also need to carefully consider the ratio you wan to run. I use a 32 to 16 or 2:1 ratio, but it is rough in hilly sections on the trail and I might move to a 32 to 18 or 1.78 ratio as I love to climb hills quickly. Hope you enjoyed it, and let me hear your comments on anything I might have forgotten!