Samd said:
krunchi said:
That type of chain failure and most failures experienced by Bafang users are a result of changing gears under load.
Can't agree with the use of "most". A lot of failures are the extra torque on a curved chainline. I've been doing this for seven years now.
I certainly did not have an upshift under load. I downshift under load constantly, but not under high-assisted load. I might have mentioned, but my riding style so far has been me doing the same full-bore ride that i had been doing w/o the Bafang, and letting the Bafang help only for the steep uphills that would normally drop me to a crawl (understandably). My Tuesday evening ride is 15 miles with most of it relatively flat (rolling long slopes with about 200' of total climb) but about 1/2-mile of it climbs 850'. On a 12S1P HK 5Ahr/222Wh lipo battery I put back in 2350Ah for the entire ride, and that included more BBS02 usage than I would normally because I aligned the chainline to 6th gear (to get it perfectly straight) and then used a fire-hydrant and the metal body of my Gerber knife to pound the link back on and limped it home up the steep hill in 6th, which pretty much meant the Bafang doing a lot more work than it would have otherwise (although I did walk it a few of the steepest blocks).
This failure I think was a combination of the severe chain line angle between the SRAM 9spd 11-32T cassette in lowest gear and the now-1x BBS02 stock CR, a chain that needs to be about 3 links longer (the stock CR on this bike was 42), being on the single steepest block of the trip which is probably pushing 20%+ grade, combined with a worn chain, and a questionable-quality chain to begin with. This was a "Surly" chain, and I've never known Surly to be very much into hardcore R&D, and who knows how old this chain was before I got it (2001 KHS bike).
I have a new Ti-nitride-coated KMC X9SL on the way; we'll see how long it lasts (my upgrade from 12S to 14S I'm working on while my chain is down won't help it's longevity, i'm sure
)
Samd said:
With thanks to Big Ron Spinningmagnets, this thread is absolute gold on chains and breakage parameters:
http://endless-sphere.com/forums/viewtopic.php?f=16&t=46630
If you observe the side link gauge for >7 speed you will see what I mean...
I'm not sure which part you're referring to, except maybe that they are skinner chains, but yeah, there's a goldmine of info on that landing page to review. At first glance it sounds like I probably need to revamp to no more than 7 gears in order to keep the chain width up ? I'll have to figure out what to do next after this one breaks.
Being relatively new to serious bike mechanics, and completly new to e-bikes, there's a lot to learn !
UPDATE/EDIT: "When a unit with a torque sensor is released that should solve all chain break issues."
Y E S ! The moment it is released, I'll have a lightly-used BBS02 available for some lucky person
-=dave