Motorizing Trek and I need a chain

[TrekElek]

I am putting a crank mount Bafang HD motor on a Trek Marlin 5. I chose the Mid level bike due to possibly being slightly overbuilt. It has an aluminum frame to help carry heat away and it has a frame warranty and my first real bike was a Trek. My concern is the chain. Is there a more heavy chain that would give me more service life? I am in the project at about $1400 and I do not want to double that cost with an IGH. I have noisy dirt bikes and there are hiking trails in the area where I can ride a MTB. The eMTB will see some jumps and I will try to avoid shifting under power.

 

[m@Robertson]

Clever screen name ;-)

First of all, an alloy frame is not going to be any sort of usable heat sink. The good news is the BBSHD doesn't need them unless you live in a blistering climate, like I used to. If that is the case you can do this:

https://talesontwowheels.com/2020/01/28/heat-sinks-for-the-bbshd-ebike-mid-drive/
Next is a little more rain on your parade... you can expect ANY frame warranty from anyone to be voided by putting a motor on the bike. Fear not... the motor is not going to hurt the frame. The Marlin 5 is built plenty strong to handle an HD.

The current Marlin 5 Gen3 uses a Linkglide cassette and a Linkglide chain. That actually should be just fine for a mid drive. I am using an 11s Linkglide chain on one of my 11s BBSHD builds and Linkglide is purported to be strong enough for mid drive use.

If you are talking Marlin 5 gen 2, thats a Shimano HG200 cassette (steel, pinned-together so ideal for mid drive) and a KMC 8s chain. KMC is the go-to for mid drive use, although the KMC 'e' line is really the one you should use. Still, I would not be feeling so bad about using a KMC Z8.3. BUT if I were inclined to buy another, it would be the SRAM EX1 for an 8s drivetrain.

Lots more advice on parts specifics here.

https://talesontwowheels.com/2022/08/01/how-to-build-a-mid-drive-ebike-that-doesnt-break/
Myself, if I were doing any Marlin I would pull out the existing shifter, derailleur and cluster and swap in a Microshift Advent 9s system for about US$100 total, where that cluster will be an 11-48T hardened steel affair that will be indestructible. Or take the extra gear and do an Advent X with its 11-46T hardened steel cluster.

Remember when doing a BBSHD you are kissing goodbye the teeny front chainring, so the smaller range cluster that the Marlin comes with is not a good fit anymore.

There is no need for an IGH... especially since pretty much all of them cannot handle the torque a BBSHD will put out. Lots of experience in this regard if you dig around the various DIY emtb user groups. You could do a Rohloff but make sure you are sitting down when you google up the price on one of those. Regardless, there is no reason to not do a chain so long as you use a proper one.

 

[TrekElek]

I do not expect Trek to honor a warranty if converted to an ebike. I imagine that the frame must be sufficient if there is a warranty. Thank you for the response. I will likely go with the MA 9s you suggested.

 

[Smaug]

...

There is no need for an IGH... especially since pretty much all of them cannot handle the torque a BBSHD will put out. Lots of experience in this regard if you dig around the various DIY emtb user groups. ...

More and more higher-end eBikes use an IGH so that they can use a belt drive. They're advertised as "eBike duty" or something. Is it just one or two? For example, the Priority Current has the option of a Shimano IGH or Enviolo CVT hub:
https://www.prioritybicycles.com/pr...NE85akhEVEhD3m5vO0AFtIrW8dsNVAxYaAp2cEALw_wcB
As you say though, that doesn't seem to make sense for this build.

 

[major masingil]

I use the KMC "e" rated chains on a 9 speed Gary Fisher HD build. Very solid chains...I might drop in something to think about...check out using chain wax instead of normal lubricants. I'm very pleased with my decision to switch to chain wax.

 

[m@Robertson]

More and more higher-end eBikes use an IGH so that they can use a belt drive. They're advertised as "eBike duty" or something. Is it just one or two? For example, the Priority Current has the option of a Shimano IGH or Enviolo CVT hub:

Yes but those commercial drives are running at much lower power levels than the BBSHD the OP is installing. Typically the max those commercial bikes are rated for is 85Nm and goes down from there.

In fact, just reading the manual even the Rohloff at 145Nm is not up to the task. However if you talk to Rohloff they will tell you that torque rating is not a peak value, but is instead a grind it out all day value (i.e. continuous). Of all the (myriad) IGH failures that you read about in the DIY groups, only the Rohloff has a near-spotless reputation (strictly speaking, the Kindernay was rated for more torque but they went belly up so not on the menu any more). There is also one Shimano that has a decent record but IIRC its a 3-speed.

 

[TrekElek]

Thank you all for the input.