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Recreational Cyclocross and Gravelbiking This has to be the most physically intense sport ever invented. It's high speed bicycle racing on a short off road course or riding the off pavement rides on gravel like :The Dirty Kanza". We also have a dedicated Racing forum for the Cyclocross Hard Core Racers.

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Old 04-20-07, 06:42 PM   #1
mncplfreedom
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Racing Singlespeed w/ Biopace?

Does anybody roll/recommend this?

I've heard rumors that biopace is more susceptible to chain-dropping, but have been curious about trying it out on the cross-check I'm looking to build for next fall.
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Old 04-20-07, 08:56 PM   #2
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on a fixed gear I think this is true (because it happened to me quite a bit)

on a singlespeed, it might not be that much of a problem because you're not exerting back pressure. It also depends how you run your SS. a chain tensioner, or a chainwatcher/blocked front derailleur will definitely help.
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Old 04-20-07, 10:54 PM   #3
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Quote:
Originally Posted by comradehoser
on a fixed gear I think this is true (because it happened to me quite a bit)

on a singlespeed, it might not be that much of a problem because you're not exerting back pressure. It also depends how you run your SS. a chain tensioner, or a chainwatcher/blocked front derailleur will definitely help.
Tell me more of this chainwatcher/blocked front derailleur method.
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Old 04-23-07, 02:20 PM   #4
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well, you can basically block your front derailleur in place using the limit screws to help catch the chain if/when it falls off.

the chainwatcher, is a plastic "tooth" that clamps to your seat tube and keeps the chain from falling off to the inside of the chainrings. If you use that with a bashguard, it should do a pretty good job of keeping the chain on the sprockets
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Old 04-23-07, 11:12 PM   #5
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Thanks
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Old 04-23-07, 11:46 PM   #6
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Or you could just spend $20 on a round chainring.....
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Old 04-24-07, 12:55 PM   #7
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I think you will have chain dropping issues. The Biopace concept never panned out in real life. Go round.
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Old 04-25-07, 12:16 PM   #8
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Check out what Mr. Sheldon Brown has to say:
http://www.sheldonbrown.com/biopace.html
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Old 04-25-07, 02:29 PM   #9
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A biopace ring will keep the same tension through the rotation of the crank. It was designed to do so, see above link. They work on both fixed and ss application. if you want one is a personal choice. It is my understanding that they do not work as well for riders who spin with a high cadence.
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Old 04-25-07, 09:10 PM   #10
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for singlespeed, where chain tension is not as crucial, as I said, I think it should be fine.

for fixies, however, judging from the anecdotal evidence alone (search the SS/FG forum for biopace), including my experience, I would definitely say that biopace does not do a very good job of maintaining even tension. Apparently, it works better the larger you go ( chainrings 50t +).

In a cross application, with a 40-odd ring, it would suck to run it fixed. If you try it, remember also to flip the ring if you use an inner ring on the outer position. This preserves the proper orientation, so they say (I just read it in FG/SS, so I have no idea if it's true).

With the flexibility of a steel frame, given a certain combination of pedal stroke and rough ground conditions, I would habitually throw my chain with 42 bp/15. Chewed up the stays real good.

I'd say if you're curious or have a biopace ring already, throw it on there, take a bunch of hard runs, see if you like it, and let us know what you thought. It's not that hard to swap rings. I think real experience will trump bogus keystrokers every time.
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Old 05-01-07, 03:11 AM   #11
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I have Biopace rings 48/18 on both of my fixed cross-style bikes, and had a 36t ring on my MTB when it was fixed. It worked fine, never threw a chain. The chain tension would change as the cranks turned, but I challenge you to find a round-ring setup where it doesn't. Throw it on there; if it works and you like it, fly your flag. If not, buy a different ring.

-Rob.
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Old 05-01-07, 06:15 PM   #12
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I've used biospace on a fixie/ss DON'T DO IT. Its ugly. On a a fixy it kills any chance of a graceful spin, and really accentuates your bounce to a hammer-like slamming. SS is less crappy, but those things really shine on a geared bike w/ a derailer. I never threw a chain but I never enjoyed it either.

jim
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