The first thing: did both bikes *originally* run at the same top speed? (you'll have to trust the customer's word on that one, since I assume you've never seen them when both were in good condition).
Water damage can cause all sorts of issues; virtually nothing is actually waterproof on ebikes.
Additionally, crash damage can also cause all sorts of issues; wire damage from this is very common at exposed areas of cabling (axle exit of motor especially).
If there is a throttle, it could have either water damage or physical damage preventing it from outputting it's full voltage. Is the voltage range of the signal the same on both bikes?
If it has PAS-only, is it torque control, or only cadence/on-off (with assist amount controled by a level chosen via the display)? If it's torque control, the sensor (in the axle for the cranks, usually), it could have water or impact damage causing less output than it should have.
There could simply be water ingress in the connectors or cabling, or the controller housing, with corrosion causing undesired or insufficient operation.
Could even be at the battery connector on the bike itself, either where the battery mates with it, or where the wires enter the back; this would show a voltage drop at the controller under load vs with no load.
The motor could have water damage in it, but usually this is either a complete failure or normal operation, or something obvious like being unable to turn the motor by hand, or taking a lot of force to do so (and this would also cause the ocntroller and battery to use a lot more power than normal to drive the motor, causing more heating and less range , boht usually significant).
stjotosv said:
Hello. A customer came into my workshop today with two identical bikes . One is almost unused and in perfect condition and the other one has been in the river a few times and sees daily abuse by their son. The beat up one does 39km/h and the almost unused one does 31km/h . All display settings are identical . Swapping the batteries does not affect anything. No bad sounds coming from the hub motor .
Can ebike controllers or hub motors be affected by the "silicone lottery"? My next step is to inspect the controllers and maybe try swapping the controllers to see if the problem follows the controller. The controllers are of unknown origin and the rear hub motors are made by Bafang