Bafang Ultra Drivetrain Wear Experience

theemartymac

Well-Known Member
Can an Ultra cause increased drivetrain wear? YUP! :)

Fair Disclaimer: I am hard on this drivetrain - 300lb rider + cargo, long high-speed commutes with high assist and sport mode, basic chain maintenance of weekly wet lube only.

I received my Rize RX Pro last September, and have been using it primarily to commute to work 45kms round trip. I run at high assist much of the time to keep the travel time reasonable, and tend to use plenty of supplemental throttle on the big hills. I only perform basic chain maintenance and lubing weekly, but do pay regular attention to derailleur alignment - particularly as the new cable stretches in. I'm at 500kms, and 8th cog is now toast and unusable with power. 7th and 9th are still decent, but I have to moderate the power to prevent occasional slippage under high power. The rest of the old cassette is like new. Chain stretch measures comfortably under 50% with the Vernier calipers. Old cassette was a Shimano Alivio 11-34 9 speed.

For comparison, my other bike is a similar Rize X with a 750W hub, and after the 1000+kms I put on it last summer, the drivetrain still looks and measures as new.

The 8th cog - damage likely mostly due to unintentional slippage over the final week or two of use.
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Interestingly, aside from the obvious damage from slipping, the visible wear is not overly significant but the cog just progressively lost grip lately under power. 7&9 are getting there quickly, so I have replaced the cassette with a Shimano HG50 11-34, and have a new 49T front sprocket (up from 44T stock) and chain to install tomorrow. Took a couple of rides after just the cassette replacement to verify performance, and it's running like new again even with the old chain. I'm hoping the new front sprocket should do a couple of things; First, get me a bit lower top-end cadence, and second, move the high-use gears down the sprocket a few cogs, so I can use the larger cogs on the hills under power.

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I'm not overly concerned with the high wear rate (Expected it, but maybe hoped for ~1000kms), but I'm open to ideas to try out for kicks - other than laying off the gas! lol

I did pick up a programming cable to try and make the drive settings a little more progressive instead of the typical Bafang "all or nothing" power delivery. I'll report back how that goes...
 

theemartymac

Well-Known Member
So after completing the rest of the drivetrain swap, I discovered one key adjustment, and have ridden about 50kms.

First, and possibly important, the b tension was waay too slack with easily 50mm (almost 2") between the cog and the jockey pulley. I should have caught this when I received the bike, but I missed it. The telling symptom that I didn't even know I had until I fixed it yesterday was the momentary pause in the electronic shifter disconnect didn't seem to match the actual shift interval, and the power could come back on before the shift had time to complete. This definitely contributed to some slipped shifts and likely some of the premature wear. Added to the fact that the engagement on the 9th cog was reduced by a full tooth (which is a lot when you are only getting 5-6 teeth in the chain already, and this may have been a big contributor. Time will tell. It's tightened up to within 10mm off the large cog now, but I am at the end of the adjustment range, so I'll have to see what I can do with the hanger. It is still much slacker than it could be on the smaller cogs, but the shift interval is much quicker and the disconnect is much more effective. I do intentionally let off the throttle/pedals during shifts, but this should help reduce 'accidents'.

And for any other RIZE owners, my Rize X was also nearly this slack in stock form. The hub was more forgiving, but I adjusted it anyway.

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The new 49T (+5) front chainring is wonderful. This has resulted in a full 2 gear shift. I am now using 3-7 fully around town, and have room left to reserve 1/2 for granny gear, and 8/9 for overdrive. 3rd is a nice comfortable 15kph for pedestrian mixed trails, and 7th gets a comfy 30-35kph. 9th now lets me contribute very comfortably up to 50kph, which is exactly what I was after for the occasional highway median portions of my commute. The majority of my miles will come in 6 or 7 now, and 3-5 is the ideal hill climbing range, which will allow larger cog engagement for high powered climbs. We'll see how this fares for long term wear.

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And finally, I made the executive decision to mount the new chainring outboard of the spider (in the chainguard slot) which gives ideal alignment to 6/7, and minimizes cross chaining 4 through 9. I won't use 1/2 very much at all, and the cross chaining is no worse than a 12 speed bike anyway. I'll watch this one and see how it holds up.

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Always open to comments and or friendly criticisms if I screwed anything up, lol :cool:
 

m@Robertson

Well-Known Member
Region
USA
You want to take a step DOWN the ladder with those Shimano clusters. The HG50 as you have illustrated has separable cogs which on a hi powered mid drive is a bad thing. What you want to use are one or two rungs down on the ladder: the HG400-9 is all steel cogs (except the smallest one on the 11T versions) and I believe the steel construction matches the HG50. Where the HG400 excels is in the fact all the cogs are welded together into a single body. You can't separate them. This is good for a mid drive because the cog digs into the cassette body not as a single piece - the load is instead distributed across the entire length of the cassette. This is not good for your cogs, but it sure is for your hub and cassette body underneath. I am in fact surprised you didn't report the cogs digging into it when you pulled the cluster. You may have a steel cassette body, which is what you want for a mid drive.

https://amzn.to/2Qgqa5Z

$32 for this one so they're also cheaper. There is a 12-36 that will work better with a mid drive by virtue of its 12T smaller cog not bogging the motor which an 11T will. Especially with your now bigger chainring. It will also have some slightly taller gears in your mid range which I think you need.

Also... the next issue is out of sight: the pawls on the cassette body. 3 are typical and more are better, but nothing beefier may be available. I have standardized on DT 350 hubs with a steel cassette body upgrade because of the ratchet engagement mech is bulletproof to a powerful mid drive like a 160Nm Bafang BBSHD. Both from others' reports as well as my own few thousand miles riding on them.

You sound like kind of the worst case when it comes to drivetrain abuse on a mid drive. Not that you are doing anything wrong. Its just a hard duty cycle. Since you are aware of the issue of chainline, I'll just make passing mention of the disaster it will be if you have the chain angled sharply in either direction. Chain will be a chain saw to your chainring teeth.

Your cluster will last longer if you never lug the motor and never ever ever shift under power. If given your weight/cargo/terrain your rear cluster is just plain going to die soon, then I suggest you step down one more level and use the HG200-9, which is the 400 without the nickel or ept coating. Also lower price at around $25. If you are going to kill one every few months may as well just buy for utility not looks. The coatings won't matter on something that will die so young.

and
 

PedalUma

Well-Known Member
Region
USA
Great photos and descriptions! Thank you. I am surprised that with the 49-T you can still get the granny gear without dropping the chain with the chainring outside the spider. @m@Robertson knows what he's talking about. Check out the Bling Ring. These are narrow/wide and bring in the chain line. They do not require a spider.
 

m@Robertson

Well-Known Member
Region
USA
Great photos and descriptions! Thank you. I am surprised that with the 49-T you can still get the granny gear without dropping the chain with the chainring outside the spider. @m@Robertson knows what he's talking about. Check out the Bling Ring. These are narrow/wide and bring in the chain line. They do not require a spider.
He can't do a Bling Ring because he's got a 130 BCD spider and Lekkie rings are all BBSHD specific, which is a shame (they have BBS02 versions too but thats it).

Here's my newest one. Just a couple weeks old. The 52T has the same big offset as the smaller 42 and 46.
PXL_20210411_005500205.jpg


I deleted my post above mentioning the Mono Veloce's singlespeed nature. Turns out they have spaced it so it will work on both 9-11 and single, which I didn't know could be done. Good thing cuz they are not cheap.

But for anyone else, the USA Made (brand name and describes where its made, too) are great, low cost 110 and 130 BCD rings that seem to work well for a mid drive. I have one of them on one of my bikes and its working great and cost me 1/3 what my Wolf Tooth Dropstop ring did on another bike.

 

theemartymac

Well-Known Member
You want to take a step DOWN the ladder with those Shimano clusters. The HG50 as you have illustrated has separable cogs which on a hi powered mid drive is a bad thing. What you want to use are one or two rungs down on the ladder: the HG400-9 is all steel cogs (except the smallest one on the 11T versions) and I believe the steel construction matches the HG50. Where the HG400 excels is in the fact all the cogs are welded together into a single body. You can't separate them. This is good for a mid drive because the cog digs into the cassette body not as a single piece - the load is instead distributed across the entire length of the cassette. This is not good for your cogs, but it sure is for your hub and cassette body underneath. I am in fact surprised you didn't report the cogs digging into it when you pulled the cluster. You may have a steel cassette body, which is what you want for a mid drive.
Thanks! That's pretty much exactly what my LBS said, although I should mention that I didn't pay for the HG50. The tech was building a new bike for his wife and it was a new take-off, so he threw it in for free since I was buying the ring and chain. But we had that very discussion about just buying the cheap cassettes and replacing them every few months going forward. He also felt I wasn't going to find anything measurably "stronger", and it would all wear quickly in any case.

I was originally going to use the freebie just to burn off the original chain, but then I though I might better assess any potential improvements that resulted from the chainring swap and adjustments if everything was new. The HG50 is the same multi-piece construction as the original Alivio, and they seem very close in spec and performance.

And Uma, I did try and get a Bling Ring over the winter, but as mentioned they don't come in 130 bcd. The adaptor required was tough to source, and the overall price was getting nuts, so I binned that idea. I did take a 30km ride today that included about 2 km of flowy single track, and It performed very well. I still didn't require 1st gear at all, and 2nd very little, but when I tried them on a few short hills for the sake of it they functioned just fine. I just don't see needing them much for the way I ride this particular bike, but time will tell. Likewise, 8th and 9th were used very sparingly now due to the chainring swap, so that should hopefully bode better for their longevity. :cool: