Guided and Self-Guided
Mountain Biking and Walking Holidays
Single Speed Build - Parts.
If you want to try the single speed thing there are three options: -
I'm only going to look at the third option. It's simple really. You just build up a bike that has one chainring on the crankset and one sprocket on the rear wheel freewheel hub. No gears, no shifter, no cables and no derailleurs. That's it. All you need is a hardtail mountain bike and you're away.
Before we deal with the build itself let's look at some of the parts that make up the bike.
Frames. Frames are interesting. On a purpose built Single Speed frame the dropouts tend to be horizontal. That is they are a slot or slider that runs parallel to the ground. This is actually how most old non-derailleur-geared bike frames were made. The slot arrangement was necessary to allow the bike chain to be correctly tensioned by simply moving the wheel back or forward in the frame and then bolting it down tightly. On modern multispeed mountain bikes the chain tension is taken care of by the rear derailleur and the bike will almost certainly have vertical dropouts. If this is the case then you will have to find an alternative means of keeping the chain tensioned.
Rear wheel. If you are going the whole hog on this build you may want to get yourself a proper single speed rear wheel. These are stronger than geared wheels because they do not have to be dished to compensate for the wide gear cassette and freewheel. On a geared wheel if you feel the spokes you will see that the drive side spokes are stiffer than the non-drive side. If you already have a wheel just use it until it wears out then you can get a serious single speed wheel if you still want one.
Which Gear ratio? One important thing to think about! You will only have one gear on your new bike and you had better make sure it matches your riding style. Your gearing will be a compromise. You need a gear that gives you forward momentum. Go too big at the back and you will pedal furiously but hardly move forward. Great for hills but so frustrating on the flat. On the other hand too small at the back and you will have great forward speed but just wait for those hills, you will be off and walking. The most common configuration is to keep the front middle chainring - that's normally a 32-tooth chainring and match this with a 16-tooth rear sprocket. If you plan to ride more hilly terrain consider an 18 or even 20 tooth sprocket but no bigger. Have a practice on your geared bike. Try riding it in one gear only on one of your typical rides. On a nine-speed cassette you will commonly have sprockets with; 11, 12, 14, 16, 18, 21, 24, 28, and 32 teeth. Select middle ring and start with the fourth smallest sprocket, that's the 16. If that's too hard try the next with 18teeth. Experiment until you're happy.
Chain. As long as it's not too worn your old chain will do. If it's worn get a new one. Any chain will do either 1/8 (BMX/single speed type) or 3/32 (derailleur-equipped bikes). Some people think that a 1/8 chain is stronger; it's certainly fatter. Getting the correct chain length can be a pain and luckily you can buy chain half-links. These are single links that are literally half the length of a normal chain link and therefore allow a little more adjustment to the chain length.
Converter Kits. These are simply kits containing a number of spacers and a single gear sprocket. The parts fit neatly onto a standard freewheel body - that's the bit where you normally find a multispeed gear cassette on your rear wheel. Most kits come with a 16 or 18 tooth sprocket and some give you both. The spacers allow you to position the sprocket on the freewheel so that it lines up directly with the front chainring giving you your single speed/gear.
Chain Tensioners. These come in many shapes and sizes. Most newer models bolt into the rear derailleur hanger but some bolt onto the chainstay. Some are spring loaded and some are fixed. They all do the same thing though and that is that they push on the chain to increase tension by removing any slack. Some push up and some push down. Debate rages about the best sort but they all work.
Enough of that; let's look at the build.
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