Unique mechanical issue with eMTBs

[RickBullotta]

Sooooo....a few weeks ago my Pivot Shuttle started skipping under load. I immediately assumed the "usual suspects" - derailleur adjustment, worn chainring/chain, worn or damaged cassette or cog, and so on. Well, everything checked out there and I even did a preventative replacement of the chainring and chain (and kept them as spares). Same behavior.

I'm then thinking "oh f*ck, it must be inside the E8000 motor". Start Googling, note that it doesn't happen often but does happen. Ugh. That means downtime and a lengthy repair cycle/warranty games.

Then I go for the cassette, thinking that perhaps one of the small cogs is worn or damaged. But when I go to remove the cassette, it's seriously stuck on. I get out the heavy equipment (big f*cking hammer) and eventually get it off. At the point, the underlying issue reveals itself...

It turns out that one of the smaller cogs on the XT cassette was actually spinning on the freehub body (it literally chewed through the metal on the freehub body and started to skip under load). Some soft alloy freehub bodies can't handle the stress of an eMTB - in this case it was an Industry Nine Hydra hub.

I got a replacement freehub body, put it on, and the issue was completely gone.

Lesson to be learned? Soft alloys aren't good for eMTB hubs. Make sure the cassette lockring is properly torqued also.

 

[Mcharza]

Yes, your powerfull legs and motor assistant is too much for aluminium freehub

 

[R120]

Yup you can chew up an alloy hub pretty easy with an EMTB

 

[Orangie]

40-50 nm on that ring will help

 

[Konanige]

Steel cassette will chew up an alloy freehub on an acoustic bike, I've done it a couple times myself, I'm surprised any manufacturer would spec one!

 

[RickBullotta]

Steel cassette will chew up an alloy freehub on an acoustic bike, I've done it a couple times myself, I'm surprised any manufacturer would spec one!

The good news is that the problem doesn't seem to exist on Micro Spline 12 speed Shimano - but I'm not ready to upgrade my drivetrain yet. Cheaper to replace the freehub body every 500-700 miles.

 

[Gary]

The good news is that the problem doesn't seem to exist on Micro Spline 12 speed Shimano

Kinda early days though, eh?
Have you seen first hand just how small the splines are that interlock the 10T sprocket with the 12t actually are? and the slim amount of spline that the 12t is actually connected to the microspline freehub body by?
I'm sure shimano will have tested their microspline interface to very high load but when fitting those cassettes it doesn't exactly fill me with confidence.

 

[JabberingJimbo]

Shimano used to have 3x tiny but long bolts that would hold most of the cassette together as 1 piece.....dont see it anymore!
Steel free hub bodies are a must.

 

[Gary]

Shimano used to have 3x tiny but long bolts that would hold most of the cassette together as 1 piece.....dont see it anymore!

Some SRAM HG cassettes do also. none of them holds the smaller sprockets that caused the OPs issue. Those bolts don't really do a great job of reducing alu freehub gouging either

 

[Slowroller]

Get a steel freehub, who cares if it's a few grams heavier

 

[RickBullotta]

Get a steel freehub, who cares if it's a few grams heavier

Not an option for I9

 

[Motoride]

Sooooo....a few weeks ago my Pivot Shuttle started skipping under load. I immediately assumed the "usual suspects" - derailleur adjustment, worn chainring/chain, worn or damaged cassette or cog, and so on. Well, everything checked out there and I even did a preventative replacement of the chainring and chain (and kept them as spares). Same behavior.

I'm then thinking "oh f*ck, it must be inside the E8000 motor". Start Googling, note that it doesn't happen often but does happen. Ugh. That means downtime and a lengthy repair cycle/warranty games.

Then I go for the cassette, thinking that perhaps one of the small cogs is worn or damaged. But when I go to remove the cassette, it's seriously stuck on. I get out the heavy equipment (big f*cking hammer) and eventually get it off. At the point, the underlying issue reveals itself...

It turns out that one of the smaller cogs on the XT cassette was actually spinning on the freehub body (it literally chewed through the metal on the freehub body and started to skip under load). Some soft alloy freehub bodies can't handle the stress of an eMTB - in this case it was an Industry Nine Hydra hub.

I got a replacement freehub body, put it on, and the issue was completely gone.

Lesson to be learned? Soft alloys aren't good for eMTB hubs. Make sure the cassette lockring is properly torqued also.

I too have the pivot shuttle but it came stock with Dt Swiss EB1550 wheels and not sure if it has the soft alloy, but it’s been trouble free for 2000 km. Is the industry nine a better wheel set?

 

[RickBullotta]

I too have the pivot shuttle but it came stock with Dt Swiss EB1550 wheels and not sure if it has the soft alloy, but it’s been trouble free for 2000 km. Is the industry nine a better wheel set?

My problem with the EB1550's was the rims, not the hubs. I flat spotted both of the OEM wheels. I built myself a wheelset with Whisky rims and I9 hubs, and the hubs are awesome other than the soft freehub. I've been building wheels around I9 hubs for 15 years or so. They're my "go-to" hubs because of the engagement and the serviceability. I've had some chats with them about the issue, and they've done some steel freehub bodies in the past, so there's hope. But they need to hear from more customers to ensure that there is demand.