Singlespeed & Fixed Gear - Track bike with gears

i saw a OK Cycles track bike with a fixed cassete on the back, and 2 chainrings on the front. it wasn't for sale though. anyone else come across anything like this?

also...there was an 80's Olmo with campy record components, that the dude was trying to sell for $4,000. kinda ridiculous.

mark what you babbling about? fixed cassette? really?

Why not? I always thought it could be fun for touring... You could climb mountains properly fixed. The splines for standard cogs could be machined straignt into the hub body. Looks like sombody did produce some hubs like that.

I wonder what happens if you try to backpedal with any force...the derailleur bends up into the chainstay?

Edit: Sheldon says: You CanNOT use any sort of pulley type chain tensioner on a fixed gear bike! You cannot use a derailer on a fixed gear bike, even as a chain tensioner, because when you resist the rotation of the pedals, you would bend the derailer. This presents a problem if you want to use a frame with vertical dropouts as a fixed gear, because there's no easy way to adjust the chain tension. This is also true of chain tensioners sold for singlespeed coasting bikes, such as the Surly Singleator.

So, no go.

I don't know about OK Cycles, but they used to do 'em like this: http://www.campyonly.com/retrobikes/2002/ciclo_piave.html

Way cool... One of those (the original vintage shifter+QR rods and axle only!) were recently sold for $1300 or so...

Actually, I would sort of be interested in a cheap replica if it works well. The trouble is it's said to need a special dropout. But the thought of leaning back that far while pedaling... Hmmm

Shamino made a fixed rear 5 speed block,and put the freewheel in the bb.I have on idea if back pressure would un-screw the sprockets.Anyone know more on those hubs?---sam

Shamino made a fixed rear 5 speed block,and put the freewheel in the bb.I have on idea if back pressure would un-screw the sprockets.Anyone know more on those hubs?---sam

Positron, on old Schwinns. Interesting early indexing system with only one adjusting screw on the derailleur.

Actually running one fixed would be similar to a "bumbike" setup - the fixed block threads onto the hub like a normal freewheel. There shouldn't be anything out of the ordinary about the hub.
However, a little loctite may go a long way. With the right setup, you could run two chainrings, use the two rear sprockets that up with them, and figure out your chainring sizes so that the chain lengths for the two combos are identical or very similar. Voila, a fixed-gear with two potentially very different ratios. You just have to get off of your bike to change them.

Shamino made a fixed rear 5 speed block,and put the freewheel in the bb.I have on idea if back pressure would un-screw the sprockets.Anyone know more on those hubs?---sam

Shimano called it FF, Front Freewheel. Or was that the Suntour copy?

The freewheeling was built into the cranks, just like the current version used for trials. Oh, sorry, you said that.

The idea was that you could shift while the bike was rolling, without having to pedal.

It did not change the world.

Now the observed trials folks have revived the idea.

And now the hubs have fixed cassettes.

Not sure what that means for the future of FG cycling. Could be pretty kool. Kogs will shear off in a whole new way now.

I was thinking that trials cassette hubs were fixed, didn't quite know how they accomplished that.

Anyhow, I would think as long as you didn't have too much of a tooth difference, you could run a rear der that didn't wrap too much chain. Maybe go with a long cage so that when the chain was under back tension it wouldn't be too far off straight and would minimize the chances of ripping it apart.

Maybe.

It's not the cassette thats fixed on Trials stuff, it's the hub's free-hub body that's fixed. Seems like it would be awesome for conversions. Totally adjustable chainline on the cheap with spacers and a BMX cog. There was a post about one of the hubs a few days back.

http://webcyclery.com/product.php?productid=16643&cat=419&page=1

Fixed trials cassette hub. They have a "6 speed" version as well. I assume it just has a shorter freehub body.

Edit: They're both 6 speeds, the other one is just mo' money.

the cassette was fixed, but there was no derauiler. it was 5 gears on the back cassette, and there were 2 front chainrings. i think it was more of an option to switch gears before a ride....as opposed to while riding.

no one replied about the dude trying to sell the Olmo for 4 grand with the Campy Record components

no one replied about the dude trying to sell the Olmo for 4 grand with the Campy Record components:cry: :cry: :cry: :cry: :cry: :cry:


oh you poor baby. i'll reply: who gives a crap? :bday:

Edit: Sheldon says: You CanNOT use any sort of pulley type chain tensioner on a fixed gear bike! You cannot use a derailer on a fixed gear bike, even as a chain tensioner, because when you resist the rotation of the pedals, you would bend the derailer. This presents a problem if you want to use a frame with vertical dropouts as a fixed gear, because there's no easy way to adjust the chain tension. This is also true of chain tensioners sold for singlespeed coasting bikes, such as the Surly Singleator.

So, no go.

I always wondered if you couldn't make a fixed-gear tensioner that wasn't spring-loaded like a derailleur, but instead mounted to the chainstay and had to be adjusted manually with a screw or something. It wouldn't work for a fixed cassette but would be good for bikes with vertical dropouts. It would function kinda the way a ghost chainring does, as a solid piece that added tension. Any ideas on whether this could work? [/off topic]

That would probably fare worse. The issue is that when the chain comes under reverse tension, it naturally pulls taught. When running through a derailleur, this can cause it to put outward pressure on the jockey wheels and bend the cage. With a tensioner, it can hyper extend the armature or smash it into the chainstay. If you build a rigid tensioner, it'll need to be strong enough to withstand that force.

I've never tried it, so I can't say for sure, but I'm of the opinion that you could run a tensioner safely so long as you insure that it's capable of safely moving to whatever position it would be in when the chain is straight. If it's in push down mode, move it a little forward so that it won't be smashed against the stay when the chain goes taunt, if in push up, move it back so that fully extended is still within its limits.

I always wondered if you couldn't make a fixed-gear tensioner that wasn't spring-loaded like a derailleur, but instead mounted to the chainstay and had to be adjusted manually with a screw or something. It wouldn't work for a fixed cassette but would be good for bikes with vertical dropouts. It would function kinda the way a ghost chainring does, as a solid piece that added tension. Any ideas on whether this could work? [/off topic]

It could work in theory. In practice, there's the question of how to attach it. It would need to attach to the chainstay, which is typically a round tapered tube. Any sort of clamp-on device that I can imagine for a tapered tube would not be secure enough to handle the very high stresses that would result.

If you rigged some sort of braze-on mount, I could see that working. Cheap tandems use something similar to adjust the tension of the synch chain.

However, if you're going to take a torch to your bike and wreck the paint job anyway, why not just install horizontal dropouts instead?

Sheldon "What's The Point?" Brown


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| Yield to temptation. It may not pass your way again. |
| --Robert A. Heinlein |
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why not use two spring loaded chain tensioners? on on the bottom half [before the cog as the chain runs] of the chain and one on the top half [after the cog]?

someone go try it for me. i don't have enough money or inclination to buy two chain tensioners right now.

apart from that, i'm sure i read somewhere *ages* ago that there was a way of making internal gear hubs fixed...

fsnl
sparky

Well, of course, as Sheldon points out, this is all silly, idle speculation, especially since all the frames I ever use come from the trash and I can spot and avoid a vertical dropout from fifty yards. I think, though, that two chain tensioners would be as problematic as my idea 'cause where would you attach the second one?

There are a few chainstay mounted tensioners intended for DH rigs. Here's some now, including a rigid design. http://www.bikemannetwork.com/biking/c/COMPCHTFRM