bmx cog on full sized bike
10-23-08, 01:02 PM
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bmx cog on full sized bike
i come from a bmx scene and i like like look of a really small chainring/cog. could i weld an 8 tooth driver on my fixie hub and use a really small chainring (keeping the same ratio). would there be any problems with doing this?
thanks,
jeremy
thanks,
jeremy
10-23-08, 01:07 PM
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yep the cog will be too wide
that's why flip flop hubs are dished on the freewheel side.
EDIT: are we talking fixed sprocket or free wheel?
that's why flip flop hubs are dished on the freewheel side.
EDIT: are we talking fixed sprocket or free wheel?
10-23-08, 01:18 PM
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its a fixed gear hub. ill examine the hub when i get home, ive got an 8t driver on my bmx bike so ill compare it and see how small i can go. if i keep the ratio the same will the ride be the same?
10-23-08, 01:25 PM
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a 1:1 ratio is basically like walking...your rear wheel spins at exactly the same speed your legs spin...artistic bikes are set up this way...you wouldn't go very fast on flatland...and if you ever go downhill your legs would look like the Roadrunner's...but if you're making a bike that's strictly for flatland tricks you'll be fine...
10-23-08, 01:38 PM
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if i make the cog smaller and then make the chainring smaller by the same increment it will ride the same way as when it was bigger. the only problem would be fitting the cog on the hub and chain rub.
10-23-08, 01:45 PM
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i think i get what you're saying...you mean do you get the same number of gear inches if you shrink the ratio by the same number of teeth (i.e. 48x16 to a 47x15)...
the answer is no...read the Gearing Primer https://www.bikeforums.net/singlespeed-fixed-gear/468351-gearing-primer.html
the answer is no...read the Gearing Primer https://www.bikeforums.net/singlespeed-fixed-gear/468351-gearing-primer.html
10-23-08, 01:48 PM
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i dont know the technicalities but i know that a bmx bike with a 8t driver and a really small chainwheel can ride exactly like one with a giant chainwheel if you get the right numbers
10-23-08, 02:15 PM
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i guarantee that if you get a 32t chainring and a 12t track cog that you won't be able to see the cog at all...it'll be completely covered by the chain and the lockring...it'll look like the chain is driving the hub itself except for the few teeth poking out the front of the cog where there is no chain...even 39t chainrings look tiny to me on track bikes...plus it'll save you the trouble of welding a cog and ruining a perfectly good track hub...
10-23-08, 02:35 PM
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keep in mind that the larger tire will repuire a different gear ration to get the same gear inches as you have on the bmx
10-23-08, 03:58 PM
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It's incredibly difficult (I've heard impossible, but I DOUBT it's that) to weld aluminum to steel (or titanium, as might be the case with your 8t DRIVER (Note: drivers and cogs are not the same).
It won't work UNLESS you have a Profile cassette hub and one of the new Profile 1 piece drivers that are both RHD and LHD compatible. If that's the case, you can just flip two of the pawls to LHD while keeping two at RHD, and thereby "fixing" the 8t driver. Doing this will probably work for a time, but will almost definitely cause your engagement ring (LOLOLOLOL) to undo itself from the shell, unless it's a press fit engagement ring, in which case I have no idea what happens. Keep in mind that Profile hubs are spaced 110mm, not 120mm like your fixed hub is spaced, so you'll have to use washers on the inside of the dropouts accordingly.
Try it and tell us what happens?
It won't work UNLESS you have a Profile cassette hub and one of the new Profile 1 piece drivers that are both RHD and LHD compatible. If that's the case, you can just flip two of the pawls to LHD while keeping two at RHD, and thereby "fixing" the 8t driver. Doing this will probably work for a time, but will almost definitely cause your engagement ring (LOLOLOLOL) to undo itself from the shell, unless it's a press fit engagement ring, in which case I have no idea what happens. Keep in mind that Profile hubs are spaced 110mm, not 120mm like your fixed hub is spaced, so you'll have to use washers on the inside of the dropouts accordingly.
Try it and tell us what happens?
Last edited by Slavic; 10-23-08 at 04:03 PM.
10-23-08, 09:54 PM
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whatever man, at least im not spending $1500 on a single speed bike like many others on here.
ill probably go with a 12t cog to make it easy.
ill probably go with a 12t cog to make it easy.
10-23-08, 10:16 PM
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Originally Posted by .jrmyrmx
whatever man, at least im not spending $1500 on a single speed bike like many others on here.
ill probably go with a 12t cog to make it easy.
ill probably go with a 12t cog to make it easy.
sure it's satisfying to ride a bike that you personally built...but it's just as, if not more satisfying to ride a bike that was custom tailored to your specifications by a person who has mastered the art of frame building...
it's like in Kill Bill where Uma Thurman goes to Hattori Hanzo to make her a katana...
now $800 for a mass produced Langster...that's just stupid...lol...
10-24-08, 04:57 AM
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Originally Posted by gestalt assault
now $800 for a mass produced Langster...that's just stupid...lol...
10-25-08, 03:35 PM
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Originally Posted by .jrmyrmx
whatever man, at least im not spending $1500 on a single speed bike like many others on here.
ill probably go with a 12t cog to make it easy.
ill probably go with a 12t cog to make it easy.
10-25-08, 04:27 PM
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Holy mother of god. BMX cog = SS freewheel kthnnx bye fixie fixie fixie fixie fixie fixie fixie fixie fixie fixie fixie fixie fixie fixie fixie fixie fixie fixie fixie fixie fixie fixie fixie fixie fixie fixiev
10-26-08, 09:14 AM
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This is Africa, 1943. War spits out its violence overhead and the sandy graveyard swallows it up. Her name is King Nine, B-25, medium bomber, Twelfth Air Force. On a hot, still morning she took off from Tunisia to bomb the southern tip of Italy. An errant piece of flak tore a hole in a wing tank and, like a wounded bird, this is where she landed, not to return on this day, or any other day.
This is Africa, 1943. War spits out its violence overhead and the sandy graveyard swallows it up. Her name is King Nine, B-25, medium bomber, Twelfth Air Force. On a hot, still morning she took off from Tunisia to bomb the southern tip of Italy. An errant piece of flak tore a hole in a wing tank and, like a wounded bird, this is where she landed, not to return on this day, or any other day.
10-26-08, 11:08 AM
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Originally Posted by K_phomma
Holy mother of god. BMX cog = SS freewheel kthnnx bye
SS splined cassette cog
thread on freewheel
BMX one piece drive cog (what the OP wanted to 'weld' to a hub)
Three different things.
10-26-08, 01:56 PM
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Originally Posted by .jrmyrmx
i come from a bmx scene and i like like look of a really small chainring/cog. could i weld an 8 tooth driver on my fixie hub and use a really small chainring (keeping the same ratio). would there be any problems with doing this?
thanks,
jeremy
thanks,
jeremy
however, using an 8t cog is a pretty bad idea. a low number of engaged teeth / severe curve of the chain will reduce drivetrain efficiency, and the cog will also wear much faster with the stress concentrated on such a small cog. then once you've quickly worn out your welded-on cog, you'll have a bit of trouble replacing it.
