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Build a "Single Speed" from the Reject Pile

08:40 29th October 1999 by Bikemagic
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Wanna try a single speed? Don’t got an
extra $2000 for a full blown, deluxe, custom "bro built" unit?


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No fear, there’s another way. With a little ingenuity, and possibly someslightly
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: SIZE="2" FACE="Arial, Helvetica">



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: FACE="Arial, Helvetica">



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.



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…).


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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 ring

and 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:



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.


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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 FACE="Arial, Helvetica">



Now for the tricky part. You can use verticals if you use a chaintensioner. 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 mech, and use the barrel adjuster to center the
jockey pulley on the single cog. Chainline tuned!


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The manual transmission option SIZE="2" FACE="Arial, Helvetica">



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.


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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. 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: SIZE="2" FACE="Arial, Helvetica">



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!



SIZE="2" FACE="Arial, Helvetica">Here’s the list for the build I did with options
listed: (click here)


Copyright ©1999 Bontrager
Cycles, Inc.

All Rights Reserved.

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