Transcript
Build a "Single Speed" from the Reject Pile (or real cheap anyway) By Keith Bontrager Wanna try a single speed? Don't got an extra US$2,000 for a full blown, deluxe, custom "pro built" unit? No fear, there's another way. With a little ingenuity, and possibly some slightly lowered personal standards, you can start with any durable old MTB frame and add some odd, out of fashion bits and pieces that are almost sure to be taking up space on the "old and tired" inventory shelf at the local shop. It's more soulful if it's steel and got rigid forks of course but it's not necessary. A little ingenuity to hook it all up and you can get a real good feel for what a single speed is like without laying down all the cash. You also get that warm, fuzzy "I did a good thing for the planet" feeling recycling all that hardware. There are even some "extensions" to the idea that are worth a look with this approach, though the pure idea of a single speed might get lost in the process. Then, if you really, really like riding it, you can take a second job, quit some expensive bad habits for a few months (or weeks if you're "one of those"), save up your money and buy that soulful indie handbuilt bike and all the special little CNC bits that go with it and be like Mike. Otherwise building one up from castoffs might just be fun enough out on the trails (fun enough = enough suffering) for you, and it's certainly got a lower cost of admission. So sit back, absorb, and plan your approach into the masochistic world of single speeds. It won't be long now; you are well on the way to unlimited knee pain and lung burn! A note about Refuse Piles: 1
Not all refuse piles are the same. I'll grant you that. I'll admit right now that I have an unfair advantage in that, my refuse pile is particularly well stocked. But, it is inappropriate to throw the stuff out, and I see a lot of stuff each year. What better use could it go to than a weird bike? (No - I am not shipping it to you - don't ask). With a little imagination, even less cash and some beer to trade I'm pretty sure the bros at the local bike shop will help you out with some of the stuff they have around too. Frame and fork: True single speed frames have horizontal slots in the dropouts so you can adjust the chain. The frames we converted in the shop used those. They work great, but you need a welding torch, or a framebuilder, and nutted axles on your hubs. Some frames have horizontal road dropouts too, and these will work in some cases. But they are rare and MTBs haven't had dropouts like this for a long, long time. That's why a lot of people pay a frame builder to weld a set of track dropouts into a frame built with verticals. Does this mean you have to buy a special frame or modify an existing frame if you want to lose all but two of your sprockets? Nope. Go out and find a serviceable old frame that is the right size and that has decent single track geometry. Rigid or suspended, doesn't matter. Rigid is cooler, and it will really make you appreciate your suspension forks after you ride it hard. There are a lot of out of vogue frames like this out there rusting away. Vertical drop outs are just fine. I "happened upon" an old frame of ours that was set up for a rigid fork and an ancient (but amazingly light!) brazed unicrown fork set up for a big frame. I cut the threads off the steerer and it was still long enough to use a threadless headset. It's a little too modern, but I am dabbling in modernity these days I guess. I can always say that it's because that's all we had laying around in the sample pile. How do you get away with the verticals??? Coming right up. 2
Drivetrain: You need to get a crank of some sort. An older MTB triple is fine. Think of all the older LX 5 bolt cranks that are accumulating as the trendy new 44/32/22 removable spider, 4 arm cranks hit. These older cranks are perfect. Long arms are good in the hills. Shorter arms let you spin better on the flats. The best crank length for you depends on where you live and how you ride (and what you find in the pile - you can always make up some story about why it's best after you get them...). Ideal gearing is the next issue, and only you can be the judge. Here in Santa Cruz, the buzz is 2:1. This is true if you are reasonably strong and fit, and a little ambitious if you aren't. We have hills. Anyway, if you start with compact cranks, a 32 tooth middle ring matches up perfectly with a 16 tooth rear BMX freecog. For a flatter area a bigger gear is cool. We used to go for mid seventies on a fixed gear road bike. This kind of gearing would make a very good city/urban unit for a strong rider. There are some tricks to taking a ring off a crank. The chainring bolts bottom on the threads before they tighten down on the ring. You can file them down a little. Or you can get some shorter ones. The fasteners that come on the 4 arm Shimano cranks are real short and fasten a single ring down nicely. If you intend to bash the thing, sanding down the teeth on an outer ringand using it as a bash guard is a great thing and that gets you out of the chainring bolt hassles. If you are really serious, a thicker commercial accessory bash ring might be necessary. These bikes make killer technicals.
Hubs: 3
You have a couple of options for hubs. An old road hub works fine. If it's threaded, you will need to re-space it so the flanges are about centered and the over locknut distance is dialed for your frame (135mm normally) and the chainline is about right. You'll need an axle. If you use the middle ring on the crank in it's normal position you should be able to work out the chainline pretty well. BMX hubs work great with a little axle length and spacer tuning. The ultimate, deluxe units have threading on both ends of the hub. One side is smaller than the other. The smaller threads let you put smaller freecogs on the hub - down to 14 teeth. The normal lower limit for BMX freecogs is 16 teeth. More on this later. You can switch the axle on one of these to a hollow unit so you can use a QR too. If you can only find old freehubs, no sweat. Bust up an old cassette and pick the cog you want. Use the spacers out of the cassette to center the cog where you need it. Lock it all down. You may need a few more spacers than you can get in one old cassette, but shops have dead cassettes laying around everywhere.
Tensioning the chain Now for the tricky part. You can use verticals if you use a chain tensioner. And, there are some very nicely machined accessory units out there just for this. But, if you are sly, you will note that any old derailleur fits the bill perfectly! Pull the chain real tight so it doesn't slap or fall off in the bumps. Silence is one of the big benefits of a single speed. It lets you hear your heart pounding and knees creaking as you struggle up hills that are too steep for the gears and even lets you hear the sounds of gushing blood in your brain on a real good day!. Cut off an old cable, pull the end up into the barrel adjuster on the derailleur. Clamp the other end in the cable clamp on the rear mech, and use the barrel adjuster to center the jockey pulley on the single cog. Chainline tuned!
4
The manual transmission option Okay, now for the second, real tricky part. When you use a derailleur for a chain tensioner, you can use more than one gear combination! This departs from the true single speed and I deserve the fate of a heretic, etc... The One and Only True Believer Jihad of the Single Speed will strike me dead one day no doubt. [Witnesses' report: It was weird. His heart burst on a climb - one that he does all the time. There were strange humanlike sounds coming out of the trees too and he was screaming "No no, I didn't mean it. I was just kidding! Ahrrrggghhh!!!" - we didn't see it happen but it must have been awful by the twisted look on his face."). But in the mean time, I'll jabber on about it. Nothing left to lose I guess. I think the combination rules. Imagine what is possible if you leave the granny gear on the crank. You can reach down and drop the chain onto that twiddle ring and get up that steepass technical hill you couldn't do on the 2:1. You have a chain tensioner! Now, if you really want a whacked set up and never intend to enter a single speed race or ride with a Jihad member, put a 15 tooth freecog on one side of the double threaded hub, and an 18 tooth unit on the other. You now have 4 (count 'em) ratios to choose from. You can ride more trails than if you only had one, and have a decent city gear to cruise with. Not bad. I am not drifting as far from the spirit of the simple bike as you might think. 1. My grandfather used to race a 2 option fixed gear bike like this in the thirties. He was bad. He knew what he was doing. Call it what you like; I'd be happy to be as fast as he was. He liked the gears. 2. The #1 challenge is still to build a simple, light bike, leave it in a single gear as long as possible and ride everything you possibly can, grinding hard on the steeps and spinning like a dervish on the flats and descents. But, now you have some ride extending options. 5
This can really make a difference if you aren't some skinny ass, expert lunged, Uber Racer and you live in the hills. And, after all, this is about having fun (okay - suffering) on a simple, light, cheap, quiet, "a bit more challenging than the latest geared wonder rig" bike. It's NOT a religious pilgrimage. (Hear that Jihad members?) Okay, so you might not need the extension to the gear range. Mike doesn't. Do what you want. Let your conscience (and your fitness) be your guide. It's there if you want it. Bars, stem, and controls and the rest: Go for what you like or can find. Keep it light if you ride in the hills. Otherwise, no big deal. Use old stuff whenever you can. Don't pay for it if you don't have to. Live by the Schwag Rules. If you haven't heard of these before, here they are: Schwag Rules! Cantilever brakes will be easy to find. We happened to have an abundance of XT V brakes that no one like to ride with because they rattle and squeal. Lucky me. Otherwise they work great. Bars should provide lots of out of the saddle leverage. Lots. Rise bars or wide flat bars and bar ends are a good thing!
6
Build a “Single Speed” from the reject pile (or real cheap anyway)
COMPONENT FRAME
FORK
HEADSET SEATPOST SADDLE BAR
STEM BREAK LEVERS GRIPS BRAKES
BB CRANK
RING 1
RING 2 CHAIN
1ST CHOICE Bontrager OR Race rigid - old stock manufacturing and pain blem Bontrager brazed Unicrown - old stock unsellable Tange 1" threadless used Bontrager race lite prototype Bontrager FS protoype Bontrager Crowbar Race 13 degree prototype Noname Taiwanese prototype 12 cm Shimano XT 1 finger used take off Bontrager Foam samples Shimano XT V brake used take off Shimano UN 52 107 mm - new Bontrager Comp Prototype
Shimano LX 4 arm 32 tooth - leftover from crank tests ??? 4 arm 20 tooth ditto an old Rohloff sample that didn't work on Shimano IG cassettes these are the best chains
ALTERNATIVE COMMENTS any decent hardtail
suspension or rigid - it just has to be sturdy enough to ride anything that fits the frame same anything that fits your butt lots of out of the saddle leverage and something good for technical work same whatever works with the brakes whatever fits your hands whatever you can find - good cantis are laying around everywhere has to be good and cheap lucky me - anything that has the length you need, preferably with rings installed see above
see above anything - inexpensive Sachs chains that don't shift on a geared bike are perfect for a single speed 7
FREECOG TENSIONER FRONT HUB REAR HUB
SPOKES FRONT RIM REAR RIM FRONT TIRE REAR TIRE TUBES ALT CRANCK
in the world - lucky me 15 tooth/18 tooth - new old Sante road derailleur - hosed very used XT 32 hole GT BMX 36 hole sealed bearing respaced - laying around 15 gauge - new BCX Red label 360 gram 32 hole blem BCX Red label 360 gram 36 hole blem Revolt SS prototype Revolt SS prototype lite presta - new
Curve 171 mm 5arm test sample ALT FRONT HUB 1 Formula sealed 32 hole sample ALT REAR HUB 1 32 hole Sanshin road respaced ALT REAR HUB 2 Bullseye 32 hole BMX - rescued from old frame factory
your pick if you have to buy this you aren't trying ditto ditto
used spokes are not a good idea if you build wheels lucky me - score a used wheel for the best deal lucky me - ditto old takeoffs are fine ditto old tubes with patches don't weigh that much for a spin machine
??? the cheap way to go not the cheap way to go, but it builds the strongest wheel known to man
Fonte: Foi copiado do site da Bontrager, mas este artigo não está mais lá. Keith Bontrager foi o fundador da Bontrager , que hoje faz parte do grupo Trek.
8
