Have any of you seen the Jan '07 Triathalete mag with the breakdown of Stadlers bike? In the picture it shows a custom rear derailleur that is oversized. Has anyone else tried/ridden with this before. He claims it gives a him a much better ride. I am no bike guru, but I have not seen or heard of this before. If it is so good why don’t others use this set-up??? Just curious. All you bike guru’s can now fill me in.
Ask Jan Ulrich. Or try one of the other billion threads on this. Search function above.
Basically the guy who makes them is only doing some one-offs right now…
there have been a couple threads on this here, and Normann even commented on one of them…
I read somewhere that Normann believes that the oversized pulley saves 6-7 watts. No studies that I’ve seen to back it up. But its hard to argue with a 4:18 bike split! 
Normann posted on here about a week ago, talking about that very topic. He basically said that he is at the point on the bike where he’ll try anything that might gain him a few seconds, as those precious seconds might make the difference in winning (like this year). I think the idea is that the large pully might save a few watts in the big picture by reducing drivetrain friction.
As per Normann (Napoleon) “I cant tell you exactly how much i saved, but it works for me. Maybe its 3 watts maybe 5 watts…! Yes, its to reduce friction and i just tried a new thing to save some seconds on the road which is very important if you win by 70 seconds ;-)”
Normann
I read somewhere that Normann believes that the oversized pulley saves 6-7 watts. No studies that I’ve seen to back it up. But its hard to argue with a 4:18 bike split!
I don’t have the source handy, but standard pulleys only require <1 watt to spin, so there’s only so much that can be saved.
*I don’t have the source handy, but standard pulleys only require <1 watt to spin, so there’s only so much that can be saved. *
**
Losses are mostly linked with the chain that goes around the pulley and not with the pulley itself. Results I have seen from chain drive systems indicate power losses from 2% all the way to 20% (the two main factors being sprocket size and chain tension). For a guy like Stadler riding at 300+ watts, chain loss could easily be in excess of 20 watts. 5 watts may be possible with oversize pulleys considering that sprocket size is a key factor.
Francois in Montreal
Why would power loss in pulleys increase with an increase ina rider’s power output? I would think that the only tension put on the lower length of chain is that supplied by the RD spring.
HH