Mountain Biking - single speed mountain bike?
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07-16-03, 09:24 AM
I have an old steel frame(vertical drop outs) I was thinking of turning into a single speed. I looked throught the single speed forum here, but most all those guys seem to be single speed rodies. I guess I dont compleetly know the advantages of a single speed other than it sounds kind of cool. And where do I get the drive train for a single speed? Do I just take the big and little ring off the cranks? and what do I do about the casette? I asume I would need a chain tentioner since I have vertical dropouts...
07-16-03, 09:30 AM
I don't know about the technical hardware aspects, but you get a great workout and you don't have to worry about shifting ;) It's different and more challenging
07-16-03, 11:19 AM
My roommate has a redline monocog mtb (with freewheel), which he let me try out once. It's kind of exhilirating how quickly it responds to pedal input and how smooth it feels. He said he's taken it on some pretty tough climbs and said it was a really tough workout, but not as bad as one would expect.
I'm not sure who makes single speed cranks, but yes, you would need a chain tensioner since you have vertical dropouts.
07-16-03, 11:29 AM
If you check on Sheldon Brown's website, there is a link that will provide you with the correct gear ratio to use for your chainstay length (distance from center of bb to center of drop-out), so you can avoid a chain tensioner.
When I built my SS up, I was just playing around with some different gear ratios to find which one would suit me. I was lucky enough that a 2:1 using the chainring I had (30T) and a 15T cog in the back worked perfectly without needing a chain tensioner. I didn't even have to measure.
regarding what you need:
1. You need to remove both derailleurs and shifters and all shift cable from your bike.
2. You can remove the big and small chainring. Or, you can find a grinder, and grind off all the teeth from the big ring and use it as a bash guard.
3. Go to most any LBS and ask if they have an old cassette, or save you one. Most can be unscrewed and you can use the spacers in between the cogs to build out the distance on the freehub body. Keep your small cog, and the lockring, and you're good to go. I've even seen some old compact discs used as spacers/chain guides for the rear.
4. Go for a ride, don't shift and enjoy!
07-16-03, 11:41 AM
Well one more big upgrade to my good bike and ill have all the original equipment back for my old bike, and can start building it up as a single speed. The casette I have is an old 8 speed, but I think only the smallest gear or two come off, the rest are all attached to each other. I guess if one of the smallest gears works I could use one of them. But what would I do about spacers? Would the bike shop have them? or can I just find a chunk of pipe and cut it off to the right length? Im thinking of getting a real bash gard, the big ring on my cranks looks like somone put a plastic plate in the microwave. Thanks for the help. Wait now that I think of it, I have 3 spare casettes. 2 very old 7 speeds and that old 8 speed. one of the must come apart right? Still need spacers though.
07-16-03, 11:47 AM
Singlespeed's are just fun to ride :D Finished building mine last week, not taken it off road yet but I've had some fun commuting on it:
I bought some old XT cranks, chainrings and the Surly Singulator chain tensioner on ebay. You might luck out like a2psyklnut and not need the tensioner... You might also need to pick up some shorter chainring bolts. My old cranks/chainrings were rivetted together and pretty flimsy hence the need for some new ones, if you already have decent parts then you won't need to buy much at all.
The rear wheel is just a normal cassette hub with a Shimano DX BMX cog and some PVC spacers to get a straight chainline:
07-16-03, 11:52 AM
Originally posted by RussellM
The casette I have is an old 8 speed, but I think only the smallest gear or two come off, the rest are all attached to each other. I guess if one of the smallest gears works I could use one of them. But what would I do about spacers? Would the bike shop have them? or can I just find a chunk of pipe and cut it off to the right length?
Didn't see this when I posted my first reply...
You can use a cog off your old cassette but you'll probably find it's going to be too small - a normal singlespeed ratio is something in the region of 2:1, 32T chainring and 16 in the back are common. The cassette cog also has profiled teeth to make shifting easy, this isn't something you want on a singlespeed :crash: See if you can get a 16 or 18 tooth Shimano BMX cog at your LBS.
The spacers I'm using are just cut from PVC piping, probably not as durable as metal spacers but just fine to start with.
Edit: Of course, if you dismantle a casette fully then you'll have plenty of cog sizes to choose from... must engage brain before posting :rolleyes:
07-16-03, 11:56 AM
Yep, most of them come apart. There are three pins holding them together. These are actually threaded, and use a 1.5mm allen wrench to remove them. There are some plastic spacers between the cogs, you can also put 2 or 3 of the seperated cogs on there initially until you find out which gear is best. I took apart one 8-speed cassette, but had two spacers in my tool box, and had 3 cogs on there to fill the void!
07-16-03, 12:17 PM
sounds like im going to have to go home and get a little greasey in the bacement tonight, and see if I can make somthing work.
07-17-03, 03:58 AM
In the UK, fixed wheel MTBs are popular for flatland trail riding, esp in winter. We get a very sticky clay mud and bikes can gather a couple of pounds of the stuff on a ride, esp around the rear mech.
Fixies or singlespeeds are lighter, stonger, more reliable and easier to maintain, but they are not recomended for steep mountainous terrain.
Uk manufacturer Dawes make a fairly cheap production model, and one of the local couriers uses it around town.
With a fixed wheel, you should not use a chain tensioner. Its much easier to build up SS or fixies with horizontal dropouts.
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