Removing BIOPACE Crank - Help Needed

salmonchild [quote]wheels [quote]31t®um the actual cranks themselves would be ok, but the rings are egg shaped and totally not suited for fixed.

Suprisingly, even the Biopace™ rings themselves are fine to use fixed.[/quote]

a guy called Ken Cox on bikeforums has written numerous long posts about his use of biopace on fixed[/quote]
fair do's, just thought that the shape would cause too many slack/tight issues, my bad.

it has the same circumference i think you mean

I know what you mean, but the chain ring will always have one quarter with out a chain on so can have eithe two low point and one high on the chain or two high and one low, Hence the tension will vary. If you get me.

Dunno if this has been answered but to get them damn plastic caps off you either use the plastic-cap-removing tool, or a pair of needle-nosed pliers.

It should be fine otherwise when riding a geared bike with Biopace the dérailleur would always be moving!?

scott not scot meaning with highs at 12 and 6 oclock.....the tension could be the same as with one high at 3 o clock because the high is further from the rear sprocket?

hehe....my head hurts.

Mine too.

Consider this simplified case where the shorter radius is zero and the longer radius is length a. The distance between the b.b and hub is b.

the first case is always a largest circumference hence tighter.

Anthony (wolfenger) It should be fine otherwise when riding a geared bike with Biopace the dérailleur would always be moving!?

A dérailleur is made to take up slack with the srping, this does not mean it will move left to right i.e along the casset / freewheel.

read this, it does go a little slack
http://www.bikeforums.net/archive/index.php/t-237290.html

man, how did we get from fondue to this science stuff.

From Sheldon;

Biopace and Fixed Gear

People are often astonished to learn that I ride Biopace chainrings on fixed-gear bikes. They imagine that there will be tremendous changes in chain tension as the chainring rotates. In practice, this is not the case. A 42 tooth chainring will generally engage 21 teeth against 21 chain rollers, regardless of its shape.

There is a slight variation in tension resulting from the varying angle between the two straight runs of chain as the axis of the chainring rotates, but this has not generally been of a sufficient magnitude to cause any problem in practice for me.

TheBrick(Tommy) [quote]Anthony (wolfenger) It should be fine otherwise when riding a geared bike with Biopace the dérailleur would always be moving!?

A dérailleur is made to take up slack with the srping, this does not mean it will move left to right i.e along the casset / freewheel.[/quote]

I was thinking more of a front to back movement. I never saw this on my old mountain bike. But then I was mainly looking forward!

From Sheldon "Biopace" Brown's site
Biopace and Fixed Gear

[cite]Sheldon Brown:[/cite]

People are often astonished to learn that I ride Biopace chainrings on fixed-gear bikes. They imagine that there will be tremendous changes in chain tension as the chainring rotates. In practice, this is not the case. A 42 tooth chainring will generally engage 21 teeth against 21 chain rollers, regardless of its shape.

There is a slight variation in tension resulting from the varying angle between the two straight runs of chain as the axis of the chainring rotates, but this has not generally been of a sufficient magnitude to cause any problem in practice for me.

I am not saying the difference in chain tension is massive, it clearly depends on how much of an ellipse the chainring is but there will be a difference in chain tension. Sheldon agrees with this point. Whether it is acceptable to you in personal. Most people get pissed of with cheap normal chainrings because they are not very round let alown a chainring designed and built not to be round.

TheBrick(Tommy) I am not saying the difference in chain tension is massive, it clearly depends on how much of an ellipse the chainring is but there will be a difference in chain tension. Sheldon agrees with this point. Whether it is acceptable to you in personal. Most people get pissed of with cheap normal chainrings because they are not very round let alown a chainring designed and built not to be round.

Here here! My Shimano chainring is in no way perfectly round. But once I realised this I just adjusted to suit. Guess it's the same with Biopace.