eMTB Cassette / Cog Wear

[GL1]

Hi all,

So after 4000 miles of eBiking on two bikes (Levo and Kenevo) I have found that by far, one of my biggest issues is "premature" cog / cassette wear. I think the additional torque of the motor just wears them out much faster than they would with leg strength alone. I never had this occur (and certainly not at the intervals and skipping severity it's happening on the eMTB's) in thousands of miles and varying drivetrains when I was riding acoustic.

To be clear, on my 11 speed setups (both SRAM GX and Shimano XT,) the drivetrains hold up well for eMTB with the exception of the three to four highest (smallest) cogs on my cassettes. These tend to get "rounded" and begin skipping within 500-800 miles on a new GX, XT, or several other brand cassettes I have tried. And, the middle and upper speed cogs remain fine for many, many miles after that.

Has anyone else had this experience and / or found a good solution?

I am tired of spending the money to replace cassettes and then entire cassettes at that. I've been looking into just replacing the two to three lower cogs alone (those that are individual typically depending on the make of cassette.) I think I have found a place that sells them individually like that for 11 speed. Maybe titanium would hold up better if I can find them in that?

Anyway, let me know if you've had the issue and if you have a solution.

PS - As a side note, due to the increased torque I have also found the beauty of using "pinned" cassettes or at least pinned in part to save my alloy freehub bodies. In this way the majority of the cassette moves as one unit against the freehub body. The individual cog cassettes like SRAM GX just eat into the freehub bodies on the middle and upper cogs. The lower (smaller) cogs on any cassette are typically individual but have a wider base so they don't do this as much I've found. Anyway, just a side note on this topic as well.

 

[chetbango]

Not sure if this would apply to you, but I noticed a lot of wear around 500 miles. I have a bike with 85Nm of torque and an XT drivetrain. With advice from a buddy with more experience, I have adjusted how and when I shift. On top of "surge shifting" (spin a faster cadence for a few revolutions so you can back off the RPM/force while you shift a few moments after spinning up), I generally drop to eco or no assist when doing any shifting under load. I also try not to shift more than a gear at a time even though I have a shifter and derailleur that can. I also more often stay in the "wrong" too high gear and just power up climbs when possible if I find myself not having downshifted early enough.
I am also pretty religious about chain maintenance. I use "Squirt" wax-type lube. Dry brush it between rides with the Park Tool Chain Scrubber. Then and about every 80 to 100 miles I use simple green to clean the chain in the scrubber and reapply the lube. Obviously there are many good options for both lube and tools, those are just what I use.
I replaced my cassette and chain around 500mi as I had hammered it pretty badly with poor shifting technique. Since then I have adjusted my shifting and maintenance as described above, and put about 600 miles on the bike and my cassette still looks almost new.

 

[pampmyride]

Depends of brand & speeds etc, but my 12 speed shimano has the 4 loose , smaller cogs available separately... in theory. None in the UK, but I found some on Aliexpress & a couple just arrived after a month in transit. My cassette has got 1600 miles on two chains & the new (3rd) chain has the odd slip on the small cogs now. The 12 speed cogs are hard to source right now & the smallest 10T is a silly price. I've seen 11 speed & some other brands offering the same so find a part number & get searching. Pic shows old & new cogs.

 

[GL1]

Thank you. Yes, I have had these thoughts...that I need to stop cranking on them so much.I dialed my power back even in turbo and it may have helped a little on this last cassette but still, I'm right over 500 miles and the lower two, the 11 and 13 are rounded and popping / slipping like crazy. Your explanation makes sense and trying to keep from quick / "torquey" shifts especially up would help as I admit I do that.

Overall, as I look at my Levo and how it's spec'd as well as how it's all worn I'm surprisingly happy with a lot of the "e" components. For me, I learned to run a double-down and I did get better "e" rated wheels. Everything else including SRAM brakes have held up over 3000 miles. But, these cassettes and even those spec'd for "e" just aren't getting it. They are going to have to come out with something better than can take the torque.

 

[GL1]

Thank you. I just found some individuals on a site. They are just the STX grade shimano and $9 each so I'll go through them but I guess I'll buy 4 (2 of the 11's and 2 of the 13's) and for 40 dollars that will cover me for another 1000 miles or so. I could buy an all new STX full cassette for $55 but I don't need the other cogs at all. Those are all still good and just don't seem to be affected by the torque or "round" like those higher (smaller) gears do.

As I said above, I think they really are going to need to create something truly "e" rated for our bikes when it comes to cassettes. For one, they need to be one unit, or near one unit to avoid freehub damage and then for two, they have to somehow wear better. Since weight is not such and issue maybe harder steel or other metal on the lower cogs. They could go overall to a larger / wider chain setup etc. but then all parts in the drivetrain including chainring, chain and cassette would be a full departure from standard component lines. Honestly, the answer is probably an internal gearbox built behind the motor! There are prototypes!

 

[timmers]

I purchased a new 2020 Turbo Levo in July of that year. A few weeks ago, heading into winter and thinking that I wouldn't be riding much more, I had the chainring, cassette and chain replaced. That's the original parts that lasted till I had about 6000 km's on the mileage counter. I cleaned the chain many times, and I'm not one to go riding in wet or really dirty condiitions. I don't have a chain wear tool and probably won't bother buying one either. I had 6000 absolutely trouble-free km's riding with the original drive train, so expect I'll get just as much with the replacement parts.

 

[iXi]

I get 3000-4000 ks out of a cassette and usually change it after 4 or so chains. Not because it's slipping but it's just not as smooth. I can only guess people chewing through cassettes are changing gears under load or there cadence is low so there is more torque through the system. I only have a Shimano motor and it only rewards high cadence so it's how I've adapted to get the most out of it.

 

[Sander23]

I had the same issue with xt and gx cassettes.
My smallest sprockets would wear out faster then my chain reaching 0.5% wear.

Eventually I switched it for sram ex1 8speed. I got it for a very good deal in Germany and haven't regretted ever since. The thooth of the cassette are alot stronger and ticker the my xt cassette.
When the chain starts skipping I just get the 3 sprocket set from sram with a new chain.
am on my 4th chain now and sprocket set now reaching almost 5000km( average is a 1200 km/chain)
Cassette still seems fine after using it for the second winter. I hope to do another 2000 km on the drivetrain.
For some it doesn't work, but for me it has become a no Brainer!

 

[jimbob]

One of the reasons I have kept the 10sp system on the bike is the longevity of components. I very rarely need more range (although annoying when I do) and the cost is so much lower.

I've been keeping a track of the running costs of my bike, and its costing considerably more than my car!

 

[Planemo]

It does make an awful lot of sense for many riders (including myself) to lose a bit of ratio range if it gets a worthwhile increase in longevity. Interesting, and maybe something I would consider, but I don't want to lose *too* much range. Whats the largest cog available in say an 8 speed? 42T? And would an 8 speed cassette fit a 12sp hub OK? Any issues with chain alignment? Or would the cassette just be the same width but with thicker cogs?

 

[thebarber]

Go larger on the front ring it pushes the wear up the cassette

 

[GL1]

I had the same issue with xt and gx cassettes.
My smallest sprockets would wear out faster then my chain reaching 0.5% wear.

Eventually I switched it for sram ex1 8speed. I got it for a very good deal in Germany and haven't regretted ever since. The thooth of the cassette are alot stronger and ticker the my xt cassette.
When the chain starts skipping I just get the 3 sprocket set from sram with a new chain.
am on my 4th chain now and sprocket set now reaching almost 5000km( average is a 1200 km/chain)
Cassette still seems fine after using it for the second winter. I hope to do another 2000 km on the drivetrain.
For some it doesn't work, but for me it has become a no Brainer!

I do think you are onto something here and I do NOT need 11 speed at all on the ebike. Hmmm? Yes, 8,9 or 10 may be the way to go to get wider and beefier cogs and durability on the e's! Nice. I'll be looking into this!

 

[GL1]

One of the reasons I have kept the 10sp system on the bike is the longevity of components. I very rarely need more range (although annoying when I do) and the cost is so much lower.

I've been keeping a track of the running costs of my bike, and its costing considerably more than my car!

I do think you are onto something here and I do NOT need 11 speed at all on the ebike. Hmmm? Yes, 8,9 or 10 may be the way to go to get wider and beefier cogs and durability on the e's! Nice. I'll be looking into this!

 

[GL1]

It does make an awful lot of sense for many riders (including myself) to lose a bit of ratio range if it gets a worthwhile increase in longevity. Interesting, and maybe something I would consider, but I don't want to lose *too* much range. Whats the largest cog available in say an 8 speed? 42T? And would an 8 speed cassette fit a 12sp hub OK? Any issues with chain alignment? Or would the cassette just be the same width but with thicker cogs?

Okay, this is a good question. If we / I go 8,9 or 10 speed say in Shimano...will the Praxis chainring accommodate all of these chains? Good question on the hub too. My Levo has the boost spacing so I'm not sure. Are all those the same freehub body? I'll be doing some homework.

 

[GL1]

Go larger on the front ring it pushes the wear up the cassette

So I did do this. I went up to a 34 Praxis on both my bikes. I like it but I swear the higher (smaller two) rear cogs actually wear worse. I can't prove it and agree with your theory but IDK, the last two GX cassettes seemed to wear faster. My only theory is that the diameter of the 34 is bigger and makes a little higher angle from the chainring to the casette thus allowing less contact with these lower / smaller cogs and allowing the chain to slip more and "round" them over a shorter period of time as the chain does not "wrap" around them as well with the bigger chainring? But it's not that much bigger so it's a working theory.

 

[GL1]

So I like the idea of going to 8/9/10 speed to get wider and hopefully longer lasting cogs. I don't need 11 or beyond speeds on the eBike and I doubt most of us do. Plus, 8 and 9 speed can be cheaper.

Here is what I've found in my research for my Levo:

The Praxis chainring should accommodate all 8/9/10 speed applications no problem.

I am running what is called the Shimano HG freehub body on my wheels. If you are new to this as I am, plenty of SRAM cassettes also use this classic freehub body. It will accommodate 8/9/10/11 and now some 12 speed grouppos. The "boost" in many of our hubs is independent of this. The other types of freehub bodies are microsplie and XD. These are specific to different grouppos like SRAM 12 speed 1x Eagle etc. You need to know your freehub to know what you can do but honestly the classic Shimano HG is the most adaptable to these different cassettes of varying speeds.