exage mountain chainset

[pistol13]

Just got this with biopace rings but i think they are not aligned correctly. Anyone know the correct biopace ring placement. Does that make sense? Cheers

 

[Corduroyboy]

I think the 'correct' Shimano alignment didn't actually make that much sense. I remember reading something about turning the long axis of the oval shape until it was as close as possible to being at right-angles to the cranks to make the most of the biopace effect.

 

[pistol13]

I would'nt mind reading that. Do you remember what or where?

 

[Xesh]

I experimented with the set up of my DX biopace rings and found that the best 'feel' came when I had moved them one position (read bolt hole) clockwise.

 

[Corduroyboy]

I would'nt mind reading that. Do you remember what or where?

I can barely remember my own name at times.......

 

[velomaniac]

Read about biopace on Sheldon Browns glossary of bicycle stuff.

I believe the biopace rings should have their long axis in line with the cranks. Oval rings lined up with long axis at 90 degrees to cranks was what caused the knee problems in roadies that poured cold water on the biopace rings when they came along.

On biopace when the cranks are near vertical and the most power can be transferred the rings are at the widest point and thus highest gear. When the cranks are near horizontal the least power can be transferred but the chainring is at its narrowest portion effectively dropping gear and thus helping to maintain traction. Pretty clever stuff for off road riding but they do feel a bit weird to cycle producing a sort of pulsing feeling but usually no knee problems as in the earlier incarnation of the idea.

Cheers

 

[REKIBorter]

Try this http://www.retrobike.co.uk/forum/viewtopic.php?t=27023

 

[stew-b]

the rings have a tab that is hidden behind the crank arm when aligned correctly.

 

[Corduroyboy]

Read about biopace on Sheldon Browns glossary of bicycle stuff.

I believe the biopace rings should have their long axis in line with the cranks. Oval rings lined up with long axis at 90 degrees to cranks was what caused the knee problems in roadies that poured cold water on the biopace rings when they came along.

On biopace when the cranks are near vertical and the most power can be transferred the rings are at the widest point and thus highest gear. When the cranks are near horizontal the least power can be transferred but the chainring is at its narrowest portion effectively dropping gear and thus helping to maintain traction. Pretty clever stuff for off road riding but they do feel a bit weird to cycle producing a sort of pulsing feeling but usually no knee problems as in the earlier incarnation of the idea.

Cheers

Aha! That has triggered my memory! I think the argument was that the converse is actually true: The most power is transferred when the cranks are horizontal - that way, the full force of the leg (assuming no SPD assistance from the other leg) is transferred into a turning moment rather than just a component of that force. Thus, it would make more sense to run the 'rings with long axis perpendicular to the cranks (although this cannot be achieved with Shimano 'rings due to the fact that they are 5-bolt. Best that can be achieved is 72 degrees to the cranks by moving them one position clockwise or anticlockwise )

 

[pistol13]

Awesome fellas. Cheers