single speed conversion question

[flydhest]

so i have an old frame that has horizontal dropouts. I have a wheel that came off a Langster that has a single speed free wheel. The frame has a crankset it it that was originally for a 6-speed free hub drive train.

Am I right in thinking that the Langster fixed-free cogs want a track/1/8" chain whereas the standard road gears want a 3/16? Put differently, what do I need to do to make this work? My brother wants to dabble in cycling including possibly a single speed, but doesn't have a lot of cash to blow on the experiment and I want to help.

[Cicli]

so i have an old frame that has horizontal dropouts. I have a wheel that came off a Langster that has a single speed free wheel. The frame has a crankset it it that was originally for a 6-speed free hub drive train.

Am I right in thinking that the Langster fixed-free cogs want a track/1/8" chain whereas the standard road gears want a 3/16? Put differently, what do I need to do to make this work? My brother wants to dabble in cycling including possibly a single speed, but doesn't have a lot of cash to blow on the experiment and I want to help.

Just run the 1/8" chain. The front wont care.

[11.4]

Most single speed freewheels are 3/32". You may be able to go 3/32" the whole way. You can ride a 1/8" chain on both 3/32" cogs and 3/32" chainrings, but they are noisy and wear faster. I wouldn't recommend that step.

If the freewheel is 1/8", your 3/32" chain won't drop down onto it properly. You can also take it to a shop with any track cogs and look at the tooth width (look at the bottom of gullet) on a known 1/8" cog to compare it. Once you are used to looking at them, it's easy to recognize. There are also specific measurements for cog width if you have a caliper, but this way is easier.

Note that 3/32" single speed is not the same as a 10 or 11 speed chain. What you want is a basic 3/32" single-speed chain from SRAM or whoever -- they are all cheap and work well. Just don't use a newer 10 or 11 speed one. If you want a really really good 3/32" chain for your own build, go scrounge on ebay for a Shimano HG-91 chain. They aren't expensive but they are the best 3/32" chain ever made, and are dynamite for 3/32" track or single speed. Last chain you'll ever buy.

[flydhest]

I heart Paceline.

[pcxmbfj]

You may want to convert the rear if quick release to a nutted axle or use something like the Surly Tugnut to keep the pedal force from pushing the tire into the left chain stay.

[tigoat]

If you want a really really good 3/32" chain for your own build, go scrounge on ebay for a Shimano HG-91 chain. They aren't expensive but they are the best 3/32" chain ever made, and are dynamite for 3/32" track or single speed. Last chain you'll ever buy.

I might try HG-91 next. How is the HG-91, which is a 7/8 speed chain compare to those made specifically for a single speed use 3/32" chains from KMC?

[oldpotatoe]

I might try HG-91 next. How is the HG-91, which is a 7/8 speed chain compare to those made specifically for a single speed use 3/32" chains from KMC?

All good and KMC has a quick link, which is great. Pretty much any chain will work..best are probably those for 6/7/8s...KMC, cuz of the link..shimano, but when ya break it to clean, either have another pin or use a KMC or Wipperman link.

[p nut]

The rear spacing on that Langster is 120mm, whereas your frame probably has 126mm. You can easily space it out using some spacers. I just used some stainless spacers from Home Depot that worked well.

[jmoore]

You may want to convert the rear if quick release to a nutted axle or use something like the Surly Tugnut to keep the pedal force from pushing the tire into the left chain stay.

this. definitely this.

[mtechnica]

Here's the deal with converting a 126mm spaced frame to singlespeed with a 120 ss rear wheel: the cog on the wheel will be where it needs to be when used with a track crankset that has a a different chain line than either of the chainrings on a road double, so you either need to use ss/fixed cranks with that wheel and the chainline will be perfect (and a track chain), or use a singlespeed adapter setup on a 130mm wheel and shove it in there and use the inner mounting for a road crank (and a road spaced chain). You want a nutted axle for fixed or 120mm wheels in general.

[p nut]

Here's the deal with converting a 126mm spaced frame to singlespeed with a 120 ss rear wheel: the cog on the wheel will be where it needs to be when used with a track crankset that has a a different chain line than either of the chainrings on a road double, so you either need to use ss/fixed cranks with that wheel and the chainline will be perfect (and a track chain), or use a singlespeed adapter setup on a 130mm wheel and shove it in there and use the inner mounting for a road crank (and a road spaced chain). You want a nutted axle for fixed or 120mm wheels in general.

I'm assuming he has square taper cranks, which means all he needs is a different BB. Track set up usually has a 42mm chainline, which can easily be acheived with a shorter BB.

[11.4]

Track has a 42.5 offset, road has a 46.5 (measured to the midpoint between the two chainrings. So if you have classic track spacing in the rear and a standard road bottom bracket and crankset, the inside ring position does pretty nicely. I've set up a number of team members with winter fixies using a road crank, with a ring on the inside (and any ring with the right BCD works fine, whether it's 1/8" or 3/32") and a cross chainring guard on the outside. That guard is mostly to make it look a bit more dressed, and in winter it keeps a little more grease off your shoes.

Note that if you are trying to be genius material and use a DA 7703 triple crankset, on the grounds that it only has one land for a chainring (the outermost one) and is milled flush on the inside, it's actually worse because the outer chainring is farther out than on a double. Wish it weren't so because those are pretty cranks with a single ring and they show up NOS awfully cheap.

One thing to watch for is that if you are mounting a single speed freewheel on a track hub, you won't always get a 42.5 mm offset. For inexpensive wheels on a good single speed freewheel setup I actually recommend using wheels with old threaded 5- or 6-speed freewheel rear hub. Old Campy Nuovo Record hubs make great hubs, as do old vintage 7400 or earlier Dura Ace or old Phil Wood freewheel hubs. You can find a great pair of wheels for perhaps $100 or so. Just spin on a single speed freewheel and you're ready to go.

Don't worry about using a quick release as long as you're using a freewheel setup. With a fixed gear, you can put a lot of torque on the hub and pull it off center. But with a freewheel, you aren't really like to pull it free if it's a good hub to begin with.

[rustychisel]

With a fixed gear, you can put a lot of torque on the hub and pull it off center. But with a freewheel, you aren't really like to pull it free if it's a good hub to begin with.


Now I've never understood why that would necessarily be so? More torque on fixed hub? Less? Different?

Care to elucidate?


My 3 fixed gear bikes are all running converted 'old' road rear hubs, I respace, redish, put in a threaded axle for nuts, if needed.

[bewheels]

It has been a while since I owned a fixed gear. And when I did have one it was for sh**ts and giggles training in the fall when I was mentally fried from a long season.
I rode it on hill terrain, by myself, in the middle of nowhere. No alley cat racing, sprinting, car surfing, etc.

With that said, here was my set up:
- Old steel frame with horizontal drop outs
- The rear spacing was 120. The rear wheel was 126. Did nothing to change this. My skinny arms could open the rear spacing 6mm to fit the wheel.
- Took an old 6 speed freewheel and welded so that it was no longer a freewheel. It was a mass of solid cogs. Yes...lots of smoldering of old freewheel grease during that process.
- Shorten whatever chain I had around at the time
- Used whatever crank I had around at the time
- Kept the brakes on the bike
- With 6 cogs and horizontal dropouts, I could hop off and 'change gears' to help deal with the terrain.
- It was cheap fun.

[mtechnica]

I'm assuming he has square taper cranks, which means all he needs is a different BB. Track set up usually has a 42mm chainline, which can easily be acheived with a shorter BB.

Can be done depending on the cranks but then you have road cranks which are long and a road chainring instead of going to 1/8 for everything which is what you want for fixed (especially because of the cogs).

Singlespeed it's fine to use road rings and chains. (and quick releases)

[p nut]

Can be done depending on the cranks but then you have road cranks which are long and a road chainring instead of going to 1/8 for everything which is what you want for fixed (especially because of the cogs).

Singlespeed it's fine to use road rings and chains. (and quick releases)

Not sure what you mean by "long," but most track cranks come in at least 172.5 length (last I checked), as do road cranks. Both can also be had in 165 or 170mm. I personally use road cranks as they're more plentiful and singlespeed 130bcd rings can be had anywhere in both 1/8 and 3/32". I have some 144bcd track cranks, too, but once the ring goes, I will probably sell it and get some 7400 DA cranks to replace them.

[11.4]

Now I've never understood why that would necessarily be so? More torque on fixed hub? Less? Different?

Care to elucidate?


My 3 fixed gear bikes are all running converted 'old' road rear hubs, I respace, redish, put in a threaded axle for nuts, if needed.

Pedaling forward in the normal manner isn't going to pull your wheel out, any more than it would do so on a regular road bike. What pulls your wheel out on a fixed gear is when you suddenly jam backwards (typically when you forget you're on a fixed) and are putting more force on the hub than you are with regular pedaling.

Frankly, I ride sprints and I don't pull a quick release on a fixie, as long as it's a good quick release, good hub, and decent stay-ends on the frame. But for those who do seem to have a problem, you'd have to explain how it happens when pedaling forward when you're already doing that with any road bike with quick releases. The only difference is when you suddenly reverse the direction of force -- which would be a potential issue with a fixie but still not with a single speed freewheel.

[Don49]

So let me ask this.

Years ago I converted a LeJuenue to SS with a flip-flop rear wheel, TA crank with outer chainring moved to inside of the spider. The chainline is perfect to within a mm.

I don't need the flip-flop now, just running SS. Could I take the original rear wheel (126mm, PW hub), thread on my SS freewheel, and get the same chain line as I have with the flip-flop wheel?