Old 02-20-11, 10:51 AM
  #13  
Barrettscv 
Have bike, will travel
 
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Join Date: Feb 2006
Location: Lake Geneva, WI
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Bikes: Ridley Helium SLX, Canyon Endurance SL, De Rosa Professional, Eddy Merckx Corsa Extra, Schwinn Paramount (1 painted, 1 chrome), Peugeot PX10, Serotta Nova X, Simoncini Cyclocross Special, Raleigh Roker, Pedal Force CG2 and CX2

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OK, Geeky bike tech here;

I've determined that the failure with my winter bike is not due to any issue with the workmanship or maintenance. The problem stems from using a modern Dura Ace hub on a vintage bike. Modern hubs are designed for vertical drop-outs. The quick release skewer and the locking nut that contacts the frame is smaller in diameter and not as hard as the old school items. Modern rear hubs are held in by gravity, torque and the quick release skewer. The axle would probably stay in place without a skewer if the pavement was perfectly smooth. Horizontal drop-outs depend on the quick release skewer and the locking nut that contacts the frame to keep everything in place. The pull on the chain can pull the axle forward on horizontal drop-outs.

The modern skewers, along with the modern hub, are the reason to the slipping. The Dura Ace hub was designed to win the TDF on a bike with vertical drop-outs. My riding style might be a factor too. I do tend to get out of the saddle and put all my 210 lbs on each leg while cranking from a stop. The chain is pulling the axle forward on the drive side under this load.

One adjustment I’m going to try is to let the axle move as far back as possible in the drop-out before clamping the quick-release shut. I'm backing out the adjustment screw to achieve this.

Currently the axle is positioned in the EO location, about mid-point on the drop-out. The lock-nut on the hub and the quick-release only clamp on the upper and lower portion of the drop-out. Only two small crescent shaped sections are holding the axle in place on each side, one at 1 O’clock and another at 7 O’clock.

By moving the axle back, the lock-nut on the hub and the quick-release will grip a larger “C” shaped area, from 5 O’clock to 3 O’clock. This might make a difference.

I’m also going to test ride the bike up a grassy hill, cranking hard at low speed as I climb. Better to fail there than on the streets.

Last edited by Barrettscv; 02-20-11 at 10:55 AM.
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