BBSHD on Klein Palomino Keeps Breaking Rear Cassette

I've put about 2500 miles on my Ebike since converting it to the BBSHD and man-oh-man does this thing like to explode final drive parts.

To date I have destroyed:

Nexus IGH 3-speed (don't even bother with this, it blew up so fast)
2 Shimano CS-HG20-7 Cassettes (exploded 7th gear and broke teeth of gears 3 and 4)
SRAM PG730 Cassettes (exploded 7th gear)
3 SRAM Chains
2 KMC Chains
Lekkie 42 tooth chainring (spectacular parts explosion, props to lekkie for sending a replacement though)

When I say destroyed, I mean shiny metal parts on the ground, not just simply worn.

So, the question I have is, is there anyway to make these parts last more than a 3 months? I have read that some of the 10 speed cassettes/chain combinations might work (here:https://electricbike-blog.com/2017/03/05/beat-on-me-i-love-the-abuse-shimano-cs-hg62-11-36t-10-speed-cassette/) but I don't have the parts for a 10 speed and that article says he only has used the hg62 for 2 weeks. The HG62 is also kinda hard to find new.

I'm 175 lbs and the BBSHD is running 1500W, so there are some resonable forces going into the rear cassette and chain. I don't shift under load, the bike has a gear shift sensor to prevent this.

Has anyone found a combination that works? Help!

Are you easing onto the throttle / power? Or hitting it hard?

If the latter, try the former, ramping power up slowly.

Or install a "cush drive" type power transfer cushion between the output of the BBSHD and the drive chain sprocket.

The times I've seen this sort of failure reported with other middrive systems, especially thru an IGH, ramping-up of power was not used. (though I don't recall if any of the posters came back to report how ramping-up or cushioning helped, for those that tried it).

With my old CrazyBike2 high-torque powerchair-motor middrive, all of my failures were caused by misalignment (itself caused by the frame twisting under torque on hte drivetrain). I don't remember if I had ramping in the controller or not, but I generally didnt' slam on the power like I do now with hubmotors.

How good is your chainline? You really only need a few gears, so you could reorder your cassette to get a better chainline. I've been running single speed from the get go and never found power lacking. Though my BBSHD is quite modified. Also, SRAM does not make good chains at all, stick with KMC or get a Connex.

I have a lekkie chainring in the front so the chainline is pretty good, particularly in gears 3 and 4 where it tends to skip first.

What exactly is a cush drive? Google search doesn't turn up much. Is there a post to link to?

Not sure exactly what info you want on it (there isn't a specific how-to for your situation; you'd have to come up with something based on the idea itself, for the parts you have or could get).

This google search for "cush drive" seems to turn up explanations that are clearer than I would have written:
https://www.google.com/search?q=cush+drive&ie=utf-8&oe=utf-8

The same search here on ES for the posts mentioning the term:
https://endless-sphere.com/forums/search.php?keywords=%22cush+drive%22&terms=all&author=&sc=1&sf=all&sr=posts&sk=t&sd=d&st=0&ch=300&t=0&submit=Search

FWIW, you haven't answered the question of how you apply power yet.

If you're already applying it slowly then a cush drive won't help.

I usually hit the throttle once I get going, but the slipping/breaking happens really at any point during the ride. So I guess mashing the throttle?

I was hoping there would be some parts to buy for a cush drive, or a standard part for bicycles. It seems that the only solutions are for motorcycles and they don't really fit a standard dropout.

In the meantime I am going to check my suspension bearings since they might be allowing more flex than normal. This problem seems to be happening more and more, making me thing the frame is bending under load. Any other ideas?

For future generations who find this on a google search:

So on your advice for checking the chainline under load, I did notice that the bushings for the suspension were worn. I replaced them and that seemed to help a lot. Hopefully this makes it last a lot longer.

Anyone know if a cush drive is something that can be bought?

I hope this resolves your issues. My palomino would go through bushes every season under pedal power alone.

jc4291 said:

I usually hit the throttle once I get going, but the slipping/breaking happens really at any point during the ride. So I guess mashing the throttle?

Click to expand...

THen try riding without mashing the throttle, just slowly rolling on the power, and see how it holds up.

If that prevents the problem, then you can invest the time and money to build a cush-drive system for your front chainring (teh one that holds the chain going to the rear wheel), so that chainring is cushioned away from the direct sudden strain placed on it by the motor/pedals.

AFAIK there are no cush drive setups for a BBSxx system yet. If you develop one that works and saves wear, maybe you could sell it to the many people with these drives.

I use a BBS02, and all I have to show in terms of parts destruction is one chain that got a link peened stiff due to shifting under power (there's no shift sensor on my bike).

I swapped a chain and cassette at a little over 600 miles because enough wear was indicated to be of concern. That said, I use $12 chains and $25 cassettes, and neither the parts cost nor the work required to replace them is a disproportionate problem. I should point out that my e-bike is a cycle truck that weighs more than 400 pounds with me on it and more than 500 pounds loaded.

I think that you're using too much power for a bicycle chain drive, or else using it too indelicately. There's a large body of programming schemes for the BBSHD; perhaps you should check them out and see if there is one focused on gentle power delivery.

https://electricbike-blog.com/2015/06/26/a-hackers-guide-to-programming-the-bbs02/

I have had good luck I guess in that I've had no broken teeth and no problems with chains breaking or excessive wear. I have a gear sensor on one bike, the other one doesn't(gear sensor is a bit iffy IMO), I rely on tapping the left brake briefly to cut power and really make it a point to pedal gently until the shift is solidly completed. I also try to not give it WOT until the bike is moving at a pretty good clip. Your problem indeed might have been related to your swingarm moving around because if you're being gentle, not stressing the drivetrain a lot with the motor's power and your chainline is good you shouldn't be eating drivetrains excessively. I'll mention one of the bikes I have the BBSHD installed on is a real heavy cargo bike and I haul weight frequently and shift going up fairly steep hills a lot, no busted chains, no busted teeth on either cassette or chainring, knock on wood.

Good luck, hope you can keep it smoothed out.

I can hit 35kph with a single 20T freewheel on back and stock Bafang 46T chainring. BBS02 running at PAS 9. Seems rather redundant for me to want to shift gears, it's the same as driving a car with automatic transmission.
OTOH I used to drive a Porsche 914 with 5-speed and loved it until I got rear-ended by a hit-and-run dinosaur.

I know there's a place for shifting gears, but I don't know how it can co-exist with high-powered e-bikes which are creating ungodly amounts of mechanical wear and tear. Which I suppose is normal as you have more parts in your system to break down. 1000 watts is a lot of power on a bike.

The solution may be a money pit where you have to start buying eveything in titanium alloy for all mechanical components. The good news is that the moon is 10% titanium dioxide so the future is in mining it and getting it back here for our toys.

I have a 1500W BBSHD using a 42-tooth Lekkie going into a Nexus 3-speed and it has been rock solid. I pretty much only use the PAS and only rarely use the throttle. When I do use the throttle, I'm very slow with applying power unless I'm already moving at a good clip. I never shift under power - not even partial power. I let the motor stop engaging before I shift. Of course I can get away with that since I'm using an IGH rather than a cassette and derailure.

It sounds like your bushings may have been a big culprit, but managing the torque may help go a long way also. Bike components just aren't engineered to handle that much power going through them, so you have to baby a mid drive when the torque is going to be at it's peak. That's my experience anyway.

you need the sram pg990 cassette

has a solid cnc machined carrier for the largest 5 or 6 cogs. so very large surface area for load distribution. Also might want to try the KMC ebike specific chains the turbo or the speed if I recall correctly.