BioPace/Ovaltech problem - need your help

[pete_mcc]

Can you fit biopace rings on a singlespeed without a tensioner??

Strangly, yes! Chris makes them for BMXs and track/fixed bikes but says:

Yes, and you won't need a chain-tensioner if the ovality is less than about 15%. But, to be safe, don't exceed 10% with fixed-gears.

Most Biopace are very lightly oval, 10% or less, so you should be good.

How do you rotate a 5 arm chainring through 90 degree's ?

I know, I know....

 

[pete_mcc]

oops double post.

 

[pete_mcc]

You may need a tensioner to use this one though:

I have got a Durham oval somewhere like this one (although not as big) and it's evil, very oval and very sharp and pointy!

 

[legrandefromage]

should look like this:

 

[Splatter Paint]

In support of my first post, Shimano ones look like this:

http://www.retrobike.co.uk/forum/viewto ... ht=biopace

The greatest diametre is where the chainring size is stamped, you can also see the tabs to aline with the crank arm in the photos.

The same position is shown on this bike:

http://www.retrobike.co.uk/forum/viewtopic.php?t=65538

SP

 

[raleighmontage]

Aha - thanks.

The outer ring on my setup isn't oval'ed, or sakae stamped. The middle one only says 38, and the inner one has loads of writing on. The outer ring is the only one with a tab...

This gets stranger by the minute - i'll assemble it all as per the photo, shouldnt go too far wrong
Thanks for your help...