Hi everyone, yesterday I managed to completely total my beloved alfine 11 after a chain derailment incident.
Some infos about the bike: its a cube editor from 2012 that i got used less than a year ago. The seller reassured me that the gearbox was maintained by a mechanic before he gave it to me. Prior to the incident everything was running normally, with the occasional adjustment needed. I did a total of ~1500km after buying the bike with 0 maintenance.
A few days ago, I noticed that the tension of the chain was inadequate. It seems like the time for a maintenance was approaching. I ordered a new chain, alfine oil and maintenance kit, new BB as it was a bit grindy, new rear sprocket. I also 3d printed the tool needed to unscrew the plastic boot of the hub to open and inspect the inner assembly of the hub.
The stuff would take a couple of days to arrive due to holiday but I still wanted to ride my bike. During the fateful bike ride, against my better judgement I got involved into a race with an extremely fit 60 year old. After drafting him for a bit I attempted an overtake. I eased off the power, downshift 2 gears to 7th and then immediately brought back the power. Next thing i feel was the chain popping off in the back and a ratchetting noise coming from the hub. I immediately stop and pop the chain back on by hand. There were no visible signs of damage. I try to continue my ride but I realize the bike would not go anywhere. When attempting to pedal with or without load, a ratcheting noise could be heard from the hub and no power could get transferred. All gears were changing fine, however none could keep tension and move the wheel. It seems like something broke internally, in the clutch or driver. I accepted defeat and went back home with the public transport.
The teardown process was smooth. The oil was in good condition but evidently some had leaked off the hub, and no immediate signs of apparent damage. All the planetary gears were fine. I had to fully disassemble it to get down to the clutch/ driver system. After removing the driver unit, the problem became apparent. One of the 2 little prongs that are part of the axle assembly, sheared off. These are interfacing via some intricate components with the gear selector that holds the shift cable on the outside of the hub. This component does not even have a part number on the shimano alfine 11 manual, as it is part of the hub axel unit. As far as I understand, this is not meant to be disassembled.
I am devasted since the hub is a write off. A new or even used hub would cost the same as what I gave for the bike (250 chf). Of course I have to admit that this was totally my fault. If the chain was tensioned properly, this would have never occurred. It is uncertain if the derailment of the chain caused a shock load and something to seize up or if the sudden torque due to ill-tensioned chained caused the internal damage which then caused the derailment. Either way it really does not matter. Its also worth stating that the plastic protective piece that comes with the rear sprocket was not installed on my bike. Again, not sure if this matters.
I was wondering if you have seen such issue happened before. Have you managed to break an internal gear hub? Do you have any ideas on how I can hack this back together, even if it means locking it in one gear? Thanks for any feedback.
by abnbedtime