I have an older mechanical 105 rear derailleur
The teeth on the jockey wheels are a little rough
What jockey wheels should I get?
Am I losing any power or causing more friction not having a newer/better rear derailleur?
In reverse order: Yes, you’re giving up a little bit with the stock 105 jockey wheels, even if they aren’t in rough shape. Shimano uses bushings for both wheels in 105, one bushing and one bearing for Ultegra, and bearings for Dura-Ace. If I remember the numbers from the old Friction Facts data set, each bushing added about 0.5 W over the average steel bearing wheel at 250 W total load, so I think it worked about to about ~0.1 W for Dura-Ace pulleys, ~0.6 W for Ultegra, and ~1.1 W for 105 and lower?
Based on that, I used to buy inexpensive stainless bearing jockey wheels from Tacx (cyclocross is hard on drivetrains), but I don’t see them as available anymore. Maybe they stopped after Garmin bought them? Either way, as long as you’re sticking with convential size 11t wheels, I’d look for similar inexpensive Delrin pulleys with steel sealed bearings. The cost/benefit for anything more expensive is about as bad as possible for anything on the bike.
In reverse order: Yes, you’re giving up a little bit with the stock 105 jockey wheels, even if they aren’t in rough shape. Shimano uses bushings for both wheels in 105, one bushing and one bearing for Ultegra, and bearings for Dura-Ace. If I remember the numbers from the old Friction Facts data set, each bushing added about 0.5 W over the average steel bearing wheel at 250 W total load, so I think it worked about to about ~0.1 W for Dura-Ace pulleys, ~0.6 W for Ultegra, and ~1.1 W for 105 and lower?
Based on that, I used to buy inexpensive stainless bearing jockey wheels from Tacx (cyclocross is hard on drivetrains), but I don’t see them as available anymore. Maybe they stopped after Garmin bought them? Either way, as long as you’re sticking with convential size 11t wheels, I’d look for similar inexpensive Delrin pulleys with steel sealed bearings. The cost/benefit for anything more expensive is about as bad as possible for anything on the bike.
^^^^This.
BBB Rollerboys
Not expensive, have bearings. You’ll get a friction reduction and longer life.
I would just buy a new Ultegra rear derailleur.
BBB Rollerboys
Not expensive, have bearings. You’ll get a friction reduction and longer life.
Seconded.
BBB Rollerboys
Not expensive, have bearings. You’ll get a friction reduction and longer life.
Seconded.Thirded.
And on losses, I don’t think the tension in the sprocket to ring section of the chain will matter (derivation of power eg 250w quoted). The tension in the chain round the jockey wheels is a function of the RD spring with a small ‘wrap’ variation and is essentially the same whether stationary or moving.
Avoiding the small ring until ‘impossible’ will achieve a greater saving of watts than jockey wheel options offer.