I should replace the pulleys in my rear DA der. Logic tells me that the ceramic bearing pulleys are a waste of money.
Anybody know of any data for these?
Found this from a manufacturers site. Saves less than a watt. I don’t know who pedals with a 500 cadence however!
"stock pulleys consume 0.78w at 500rpm, while Ceramic Speed ceramic pulleys consume only 0.06w. "
wouldn’t the 500 rpm refer to the number of times the pulleys rotate, and not the cranks?
That’s what I would think, and I’d bet that’s a failry typical RPM if that’s what the stat is based on.
The G-pulley on DA is ceramic sealed bushing. The Tension pulley is a sealed bearing. It seems like a lot of money for just one pulley upgrade. I’ve seen DA pulleys sell for less than thirty bucks.
"wouldn’t the 500 rpm refer to the number of times the pulleys rotate, and not the cranks? "
Duh. Yup.
Think I’ll stick with the DA ones. Hard to justify spending three times as much to save less than a watt.
i’m curious to see if rappstar’s gonna post on this thread.
he’s usually an advocate for getting the best pulleys possible.
If you’re looking for that last millisecond in the TDF TT, maybe the .72 watt saving counts, but for my road bike it’s hard to justify. It’s bad enough that I’ve updated to ceramic bearings in my wheels and BB.
Found this over at Bike Tech Review. Seems to suggest that the ceramic pulleys could be slower?
http://biketechreview.com/phpBB2/viewtopic.php?t=1097&highlight=ceramic+bearings
Is there a functional difference between the G- and Tension pulley? I disassembled my Ultegra rear der. & cleaned the pulleys, and I noticed that the two had different resistance levels (in addition to other visible differences). The top pulley doesn’t spin freely, while the lower mostly does. Is there a reason why I couldn’t take the lower pulley from my road bike & put it in the top position on my tri bike, so both spin freely?