Paris - Nice time trial.

Tour de France, Giro d'Italia, Vuelta a España, Tour Down Under and more

Paris - Nice time trial.

Postby Johndec » Mon Mar 12, 2012 5:46 pm

Hi. Just watching a reply of the last stage of Paris-Nice, the 10k time trial. Do I need new glasses or is Wiggins riding a bike (Di2) with non circular crank rings? They appears to have a slight oval shape to them to correspond to his pedal downstroke.
Image
User avatar
Johndec
 
Posts: 155
Joined: Thu Nov 03, 2011 7:10 pm
Location: Sydney

by BNA » Mon Mar 12, 2012 5:56 pm

BNA
 

Paris - Nice time trial.

Postby RonK » Mon Mar 12, 2012 5:56 pm

Johndec wrote:Hi. Just watching a reply of the last stage of Paris-Nice, the 10k time trial. Do I need new glasses or is Wiggins riding a bike (Di2) with non circular crank rings? They appears to have a slight oval shape to them to correspond to his pedal downstroke.

Probably - they are in common use on TT bikes and some riders even use them on their road bikes.
They were introduced by Shimano about 20 years ago. I had a bike fitted with their Biopace chainrings.
They are claimed to help pedal through the dead spot at the top of the pedal stroke.


Posted via Tapatalk
Last edited by RonK on Mon Mar 12, 2012 5:59 pm, edited 1 time in total.
Cycle touring blog and tour journals: whispering wheels...
User avatar
RonK
 
Posts: 5221
Joined: Mon Aug 24, 2009 2:08 pm
Location: Brisbane, Queensland

Paris - Nice time trial.

Postby toolonglegs » Mon Mar 12, 2012 5:59 pm

Yes oval chain rings, but very different orientation to the ones of 20 years ago
Image
User avatar
toolonglegs
 
Posts: 14329
Joined: Fri Jun 29, 2007 7:49 pm
Location: Somewhere with padded walls and really big hills!

Re: Paris - Nice time trial.

Postby Johndec » Mon Mar 12, 2012 6:03 pm

Thanks Ron. Just did a bit of googling and it appears they have been around for about 20 years. Never noticed them before and it appears Wiggins is a big fan of them. He might be onto something. He won the TT :shock:
Image
User avatar
Johndec
 
Posts: 155
Joined: Thu Nov 03, 2011 7:10 pm
Location: Sydney

Re: Paris - Nice time trial.

Postby JV911 » Tue Mar 13, 2012 9:04 am

wiggo uses O.symetric chainrings
<---LACC--->
<---BMC SLR01--->

User avatar
JV911
 
Posts: 5451
Joined: Mon Sep 01, 2008 1:22 pm
Location: Sydney, Australia

Re: Paris - Nice time trial.

Postby population100 » Tue Mar 13, 2012 9:05 am

They can (apparently) hamper shifting. I believe Wiggins dropped out of the 2009 world TT championships due to mechanical problems shifting from large to small chain rings.

He seems to have fixed that now though.
population100
 
Posts: 73
Joined: Wed Nov 16, 2011 12:54 pm

Re: Paris - Nice time trial.

Postby toolonglegs » Tue Mar 13, 2012 5:06 pm

High point of the oval on old Biopace is in line with the crank arm... these days they run it a 90 degree angle.
Image
Image
User avatar
toolonglegs
 
Posts: 14329
Joined: Fri Jun 29, 2007 7:49 pm
Location: Somewhere with padded walls and really big hills!

Re: Paris - Nice time trial.

Postby JV911 » Wed Mar 14, 2012 11:32 am

toolonglegs wrote:these days they run it a 90 degree angle


yep and adjustable in the case of Rotor

mine shifts prety well but maybe not as crisp as a traditional chainring (given the distance between the derailleur and the chainring is not constant)
<---LACC--->
<---BMC SLR01--->

User avatar
JV911
 
Posts: 5451
Joined: Mon Sep 01, 2008 1:22 pm
Location: Sydney, Australia

Re: Paris - Nice time trial.

Postby toolonglegs » Wed Mar 14, 2012 3:13 pm

JV911 wrote:
toolonglegs wrote:these days they run it a 90 degree angle


yep and adjustable in the case of Rotor

mine shifts prety well but maybe not as crisp as a traditional chainring (given the distance between the derailleur and the chainring is not constant)


Not 90 degree adjustable though... unless you want to put them on the wrong bolt holes :P .
Image
User avatar
toolonglegs
 
Posts: 14329
Joined: Fri Jun 29, 2007 7:49 pm
Location: Somewhere with padded walls and really big hills!


Return to International and National Tours and Events

Who is online

Users browsing this forum: Red Rider, stevecassidy



Popular Bike Shops
Torpedo 7 Torpedo7 AU
Ground Effect Ground Effect NZ
Chain Reaction Cycles CRC UK
Wiggle Wiggle UK
Ebay Ebay AU



InTouch with BNA
“Bicycles BNA Twitter
“Bicycles BNA Facebook
“Google+ BNA Google+
“Bicycles BNA Newsletter