Bosch chain came off.....

#1
Today my chain jumped ship but luckily was near home so walked back to mess with it in the garage rather than in a feild. As it happens this was the right thing to do as it could not be coaxed back on the sprocket without removing the spider and chainring! Not good if miles away from home and no international rescue backup. This is the second time and in exactly the same place (coming slowly over a few stones off road downhill) so I need to understand what's afoot. Chain got past chain guard and guard mounting screws and was well stuck between chainring and engine casing. Any ideas on what's wrong and how to avoid this happening again would be greatly appreciated..
Thanks
Phill
 

wissy

Esteemed Pedelecer
Jan 26, 2013
524
13
Wales
#2
This is exactly what had been happening to mine... (KTM Macina Dual HS) Initially I assumed it was the actual spider which was loose but it happened several times. The last time it happened was the same time the motor seized. Now I am unsure if they were related or just pot luck it happened that last time. It seems my hub is also an issue but I am unsure if this would have been a cause for chain to come off. Check spider is tight first?

Damned annoying the chain getting stuck.. always happened to me late at night as well ........ Shouldn't really get stuck there should it? really difficult to get chain off without taking everything off.

maybe David from electrifyingcycles can give you a clue based on what he's seen on my KTM which he is in process of fixing. Martin at ebikeshop may be able to suggest something as well. i never really did get issue solved.
 

EddiePJ

Esteemed Pedelecer
#6
If you are riding on rough terrain, I'd also think about a clutch rear derailleur.
It eliminated this issue completely from the BH, where as the Haibikes chain frequently jumps on rough terrain. I must add that this is absolutely no fault of Haibike or the system. Just my use of the bike. I might well get one fitted to that, just as an experiment. :)
 
#8
If you are riding on rough terrain, I'd also think about a clutch rear derailleur.
It eliminated this issue completely from the BH, where as the Haibikes chain frequently jumps on rough terrain. I must add that this is absolutely no fault of Haibike or the system. Just my use of the bike. I might well get one fitted to that, just as an experiment. :)
The clutch mechs do help significantly! Such a great invention into the MTB world.

Regards
Martin
 
#10

EddiePJ

Esteemed Pedelecer
#12

wissy

Esteemed Pedelecer
Jan 26, 2013
524
13
Wales
#13
Is that on the new haibike trekking?
 

RobF

Esteemed Pedelecer
Sep 22, 2012
4,442
125
#15
The chain unshipped on the MH7 while going over a very modest bump.

Fortunately, no harm done, it didn't jam and I was able to put it back on at the roadside.

I suppose that is one advantage of the new Bosch motor, the small chainring makes it very unlikely the chain will come off.

Although I see some full sus mountain bikes come with a jockey wheel, like this AVE:

http://www.emotion-technologies.de/ebikes/ave/xh-offroad-pedelecs/
 

halfer

Esteemed Pedelecer
#16
I've had this problem with my Ave XH-3, running the Bosch Classic crank drive. Good to hear it can be fixed!

Thanks Martin for that blog post. I have that on/off widget on my new KTM Action Macina, and I wondered what it was for.