Re: Bike Mechanics Impart Their Wisdom On Vorb

Postby neels on Wed 26/Oct/11 8:34pm

So no, maybe, and a possibly yes. :crazy:

The oval vs overall diameter thing was what I couldn't get my brain around, and if the longer diameter was cancelled out by the shorter diameter and vice versa.

I guess I'll just have to chuck a chain on and see, at worst I'll have a couple of biopace chainrings to add to the other stuff in the bits left over box.
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Re: Bike Mechanics Impart Their Wisdom On Vorb

Postby Oli on Wed 26/Oct/11 9:01pm

Ok, so I'm definitely no scientist. No wonder I only got 33% for School C maths... :cry:
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Re: Bike Mechanics Impart Their Wisdom On Vorb

Postby danose on Wed 26/Oct/11 9:45pm

Conners wrote:Thinking about this again for a minute though there is a chance that that even though the diameter is changing that the tension remains the same. The amount of chain wrapped around (half) the ring may stay constant? (ie the bigger diameter bits might be cancelled out by the smaller diameter bits?)

I'd go with Oli. If he says it works it will work!


I've still got a (geared) bike with biopace (the II series - less extreme ovalness) kicking around, and when I spin the cranks there's zero movement in the der cage (which indicates it's not making up for changes in tension) so I reckon Oli-san could be onto it!!

now your mission conners is to put your thinking cap on and write a model for the system to prove it
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Re: Bike Mechanics Impart Their Wisdom On Vorb

Postby Oli on Wed 26/Oct/11 9:48pm

I thought I was Oli-chan? :(
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Re: Bike Mechanics Impart Their Wisdom On Vorb

Postby Astoria Paranoia on Wed 26/Oct/11 9:50pm

Astoria Paranoia wrote:Also just checking that the Stans universal tubeless valve will work in XT wheels amirite?


bump? :blush:
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Re: Bike Mechanics Impart Their Wisdom On Vorb

Postby musta on Wed 26/Oct/11 10:37pm

Biopace is not oval, its a f-ed up shape.
See here: http://www.trademe.co.nz/sports/cycling ... 182335.htm

I would not bother with them for singlespeed unless you can't be bothered getting a new normal ring
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Re: Bike Mechanics Impart Their Wisdom On Vorb

Postby Simonius_Titius on Thu 27/Oct/11 12:12am

Each Biopace ring is inhabited by a Japanese spirit which magically pulls the chain in and out on each revolution to avoid slackness.

Sheldon Brown ran a Biopace singlespeed but a local fixieist told me he tried it and the tension wasn't acceptably constant. Perhaps his ring was worn unevenly, which Biopace is very prone to.

Biopace feels weird at high cadence so with later versions Shimano reduced the coefficient of F'dness of the big ring.
There were at least three generations. The last and most sane was Biopace HP, it has a black label.

I have a pristine 52T Biopace and various round rings in Chch you can have a play with if you like.
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Re: Bike Mechanics Impart Their Wisdom On Vorb

Postby XCrazy on Thu 27/Oct/11 12:30am

Yes oval rings can be done on a single speed and I offer proof!

http://singletrack.competitor.com/2010/ ... 9&pid=2612

Of course, an oval chainring on a bike without a derailleur or chain tensioner means that the chain becomes alternately slack and tight as it rolls over the chainring. Birtch set his up so that it’s tight at three o’clock in the pedal stroke, and loose when the cranks are vertical. “At the loosest spot, there’s more chain wrapped around the chainring – there’s better contact so it’s less likely to fall off,” said Birtch. “I’ve actually never had it fall off until just last weekend, and that was because I actually went to jump this double thing, and actually cased it on the other side and it spun my eccentric therefore loosening my chain considerably. It wasn’t anything’s fault except my poor riding technique.”
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Re: Bike Mechanics Impart Their Wisdom On Vorb

Postby ratrod on Thu 27/Oct/11 2:15am

This did my head in a bit so I drew a picture. There will be a change in tension but probably only an issue if x/y is large.
Small Ellipse.JPG
Large Ellipse.JPG
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Re: Bike Mechanics Impart Their Wisdom On Vorb

Postby shmoodiver on Thu 27/Oct/11 7:20am

Astoria Paranoia wrote:
Astoria Paranoia wrote:Also just checking that the Stans universal tubeless valve will work in XT wheels amirite?


bump? :blush:


not sure maing, the shimaingo valve is quite different
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Re: Bike Mechanics Impart Their Wisdom On Vorb

Postby Percy Pig on Thu 27/Oct/11 8:46am

shmoodiver wrote:
Astoria Paranoia wrote:
Astoria Paranoia wrote:Also just checking that the Stans universal tubeless valve will work in XT wheels amirite?


bump? :blush:


not sure maing, the shimaingo valve is quite different

According to Joe the Joe's ones fit/ work with Shimaingo vheels. :)
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Re: Bike Mechanics Impart Their Wisdom On Vorb

Postby Wobbler on Thu 27/Oct/11 8:51am

does joe have a rimstrip that would go into a stans flow with a schrader valve?
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Re: Bike Mechanics Impart Their Wisdom On Vorb

Postby danose on Thu 27/Oct/11 9:05am

Percy Pig wrote:
shmoodiver wrote:
Astoria Paranoia wrote:
Astoria Paranoia wrote:Also just checking that the Stans universal tubeless valve will work in XT wheels amirite?


bump? :blush:


not sure maing, the shimaingo valve is quite different

According to Joe the Joe's ones fit/ work with Shimaingo vheels. :)


they sure look a lot closer to the real shimano ones (which I have two off here in my hands) than the stans one!
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Re: Bike Mechanics Impart Their Wisdom On Vorb

Postby Percy Pig on Thu 27/Oct/11 9:07am

Wobbler wrote:does joe have a rimstrip that would go into a stans flow with a schrader valve?

Ahh maybe? :huh:

The widest one Joes have at the moment is for 19-25mm rims, a Flow is 28mm with a rather low height, so it might work.
I cant guarantee that it will work though. :(
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Re: Bike Mechanics Impart Their Wisdom On Vorb

Postby SlackBoy on Fri 28/Oct/11 12:27am

danose wrote:
Percy Pig wrote:
shmoodiver wrote:
Astoria Paranoia wrote:
Astoria Paranoia wrote:Also just checking that the Stans universal tubeless valve will work in XT wheels amirite?


bump? :blush:


not sure maing, the shimaingo valve is quite different

According to Joe the Joe's ones fit/ work with Shimaingo vheels. :)


they sure look a lot closer to the real shimano ones (which I have two off here in my hands) than the stans one!
The stans ones do work
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