Crank arm falls off
One problem that is less expected is the loosening or loosening of the left crank arm on cranks with ISIS mounts. It is not a Stromer-specific problem and also happens with other brands. The problem announces itself and does not happen immediately.
Cause
The cause is usually the assembly. The screw lock applied at the factory is not very tight, so that the crank can come loose even if it is fitted correctly. Furthermore, the M17 screw connection is sometimes incorrectly greased (because this is sometimes the case with other cranks).
Repair
The left crank arm's construction is self-extracting, and it doesn't require any special tools to remove it. You can loosen the arm counter-clockwise with an 8mm Allen wrench.
The M27x1 pull ring must be loosened clockwise, against the arrow.
The thread of the crank screw and in the axle must be degreased and cleaned. Afterwards, the crank screw or the thread in the axle can be fitted with a little Loctite 242 and fastened with the torque specified on the crank screw.
See also Video1 | Video 2 | Video 3
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The Puller consists of four parts, an M17 screw with an 8mm internal hex, an M27x1 retaining ring, a MW497 domed spacer, and a MW080 spacer.
AL stands for Aluminum - these rings are available in different materials (e.g., also steel for Shimano cranks), and AL denotes the aluminum version, which is typically used for FSA or other aluminum bottom brackets.
LH stands for Left Hand (Left hand) – this means that this ring is a Left-hand thread (counter-clockwise to tighten). This is common for bottom bracket/crankset components on the left side of the frame so the connection doesn't loosen on its own from pedaling motion.
See also PROBLEMS – chain (-wheel) / pulleys and belt – ‚Wear: Chainring / Bottom Bracket (Spare parts(‘
Crank arm cannot be released
Solution variant 1: Drive a few meters.
Solution variant 2Treat the crank from behind with a little rust remover (e.g. WD 40) and then leave to work for 24 hours. Alternatively you can use Coca Cola - no joke. Then lightly tap the crank arm around the bottom bracket axle with a rubber or soft-face mallet - the crank should then come loose.
Solution variant 3Heat the crank arm around the crank axle with a hot air gun - the crank should then loosen.
Solution variant 4Use a professional squeegee.