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The SRAM 2 speed Automatix is a no brainer for your city bike. When cruising around town, the 2 speed centrifigul clutch chooses the right gear for you so that you can concentrate on the road. SRAM’s hub bases the gear changes on your speed and keeps your hands on the grips steering and not having to worry about shifting. No shifter and no cables means that you won’t have to maintain derailleurs and your bike will always be ready to hit the road.
Reviewed by 1 customer
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Comments about SRAM Automatic 2-SPEED Hub Coaster Brake:
I have this hub assembled into a 700x25C wheel, running 175mm cranks, 43T-19T to give about 60 gear inches in low. I'm 6'2" and weigh 213 pounds.
The hub changed gear well before reaching a comfortable cadence in low gear. I've adjusted the spring so that it's ends shifted from 5 o'clock to 9. I may adjust it a little further in future.
Operation is now much improved. When pedalling uphill or into a headwind, low gear can be used without it changing gear and having to stand on the pedals.
The hub is easy to disassemble, just undo the two big nuts on the brake end. Tightening these nuts also sets the preload on the bearings. A flat 22mm spanner is needed for locking them back up after adjustment.
Beware, when using two small screwdrivers to remove the tiny circlip (to get at the spring), it tends to pop off and fly away.
I probably wouldn't bother buying another one of these with the brake. It's grabby tending to give weak braking, then lock up. It also means you can't rotate the pedals backwards to adjust starting position at traffic lights, etc.
The dust shields don't look like they will keep heavy rain out. I will ride this through winter, and keep an eye on what gets inside. I have been thinking about filling the inside of the dust covers with grease to prevent water and grit getting in.
Tenacious oil has been recommended for lubricating centre of the hub, and by first appearances this is probably a good idea. The spring is not particularly strong and I suspect it wouldn't take much grease/dirt/grit/gunk to interfere with the gear change operation.
I also peeled off the SRAM logo sticker that wraps around the centre of the hub. Need to do this before lacing. It's shiny medal underneath and anyone looking at it would probably think it's single speed.
The spoke holes are quite large diameter resulting in the spokes I've bought not sitting against the flange. They may fatigue in future. I should probably have used washers or extra thick spokes, time will tell.