Winfried

Hello,

I notice that the Nexus 8 SG-C6001 has very low latency in a 16" wheel, even with its needle-bearing pinions: After putting the bike on a stand and giving one turn of the crank, the wheel stops spinning after just a few seconds :-/

Before I bother, does someone know from experience whether an Alfine 8/11 has significantly less drag, or should I really move to a derailleur transmission instead?

Thank you.


https://www.sheldonbrown.com/nexus8.shtml

Rick_D

Can check later but from memory, my Alfine 11 wheel spins for a time, as long as the disc brake isn't dragging. It coasts like any other bike, except for the silent bit. That's a pleasant change.

Never had a Nexus bike and cannot compare.

ETA Gave it a spin by hand and it comes to a stop after about eight revolutions, probably more drag than a standard drive but not dramatically so.

Riding it I notice the drag of 72 spokes more than the hub, I think. Most of any bike I've owned in decades. Minimum for an Alfine is 32 I believe.

sweeks

I have 2 Nexus-8 hubbed wheels, and one with an Alfine-11; all 20" wheels. They definitely don't spin as long as a wheel with a freehub. But much of that apparent internal resistance isn't apparent when these wheels are ridden. There is a trade-off between efficiency (freehub/derailleur) and the benefits of the internal gearing: shifting while stationary, simplified chain configuration, etc. IGH drivetrains are great for commuting; maybe less so for recreation or touring. (I've done centuries on my folders, so it's not impossible.)
Another consideration is that a 16" wheel will be more sensitive to hub friction* than larger wheels simply because there's less momentum.
EDIT: *When the wheel is spun, not so much during riding.

Winfried

Thank you.

Although it's not meant for that use, I ride that bike for touring, and I can tell it takes more effort than riding a derailleur-powered bike.

Before getting an Alfine 11 wheel, I might dip the N8 into gear oil (eg. Mobil Mobilube 1 SHC SAE 75W-90 Automotive Gear Lubricant, I read) and see if it reduces drag enough.

tcs

How much of the inner mech rotates when coasting? Is the drag/spin down the same in every gear? I read on the internet (and if you see it on the internet, it must be true) that 5th gear was best for coasting (?).

I'd expect the quieter Alfine version to have MORE drag, since it uses a roller clutch instead of pawls.

...and make sure your cup&cone axle bearing aren't too tight, as they often are from the factory.

base2 

I've never known any of the Nexus 7, 8, or Alfine 8 speed hubs to have excess drag that affected real world performance in any meaningful way. Most of the drag, as far as I can tell, is simply the constant of the seals doing their thing. Sure there is a bit of loss from grease & meshing gears. But it's only a couple of watts different than a conventional derailleur drivetrain. Easily comparable to rolling resistance or dirty & cross-chained gear selection. Nice tires can mitigate any/all hub inefficiency as far as I'm concerned and get you back to square zero in the efficiency department.

In short, the spin down test doesn't really tell you much. There really isn't much of a comparison between a pound & a ½ of rim & tire compared to the momentum of 200 pounds of bike and rider. Put your concerns on to things you can control.

That being said: Proper bearing adjustment & the occasional servicing isn't going to hurt. The bearings should be just tight enough there is no detectable play at the rim edge; no more.