maxants33

Hello
My Sturmey archer S2C hub failed me recently, after a reasonable run of good cycling, I really loved the hub.
I'm going to strip it soon and see if i can diagnose the problem or see any overt damage.
I will probably just replace the internals, but before i make any big purchase in new internals - i was wondering if anyone with hub gear expertise could advise in possible failure points - just incase the wheel needs rebuilding.

The problem started when starting cycling at a junction - the back wheel felt like it was loosing traction, as if i was on ice. When i look the drive train was turning but no wheel movement, but with some slight resistance. The wheels turned when the bike is lifted off the ground, but not when on the ground.

I pushed a bit till the down hill section, and when i tried to use the coaster brake, that too engaged slightly and then just completely failed.

The hub is not very old and not that far ridden. But i i note the dates on the paperwork that came with the hub are all 2010. I understand sturmey's first batch if these hubs were flawed.

Any ideas as to what's wrong?

On an internal gear hub sidenote, i have just cycled across the Namibian desert using an SRC3 3 speed hub. I was really surprised a 3speed hub would cope so well.

A 3 speed hub in the desert

Moe Zhoost

My most severe wild guess from your short description is that you've damaged the pawls or ring gear. Perhaps a broken axle. Maybe the shift mechanism is sticking. Hard to tell without disassembly. These are relatively simple hubs so I'm confident that if you take it apart, the cause will be obvious and easily fixed.

maxants33

After disassembly and no clear issues yet ongoing failure of the transmission - i bought a new set of internals.

When going to change the internals - and popping off the sprocket; I noticed the teeth that seat the sprocket had sheared! Popped on a new sprocket and everything is good. So wasted money on a new set of internals when it was a £2 fix in the end 🤦🏻

Moe Zhoost

Thanks for the followup. I have never heard of this happening. This goes to show that our minds always seem to focus on the complex rather than the simple.

I take it that you didn't remove the sprocket from the driver when you first took it apart.

maxants33

No I didn't take it off. But the 3 seating teeth on the sproket had mostly crumbled and the remaining fragments were compacted into the grooves.

I had noticed there was a looseness to the transmission for about 6 months leading up to it that was getting worse but was pretty much hiding my head in the sand 😂

I think its because its a kick back hub with a coaster brake - so every ride the sprocket is forcefully and rapidly being rotated backwards and forwards many times in a ride. The small amount of play available between the hub and sproket must been partially responsible.
Its my commuter bike of about 4 years doing 24km a day + some light day tours, so possibly around 30,000km on this sproket.

I think I will seat the new sprocket with a little epoxy over the 3 teeth to fill the voids and limit the play forward and backward.

Dan Burkhart 

I encountered this a few times when I was servicing industrial trikes that were used on a plant floor in a drywall manufacturing plant. Those guys would ride around the plant with 500 lb or more on the load tray so those lobes were under a lot of stress. Plus they were used every day all day.