Derailleur, chain, and cassette recommendations for lower gearing

[createthis]

I have an older Felt Dual-e. I think I bought it back in 2015. It is a gen2 Bosch mid drive and has about 500 miles on the OD.
One of the things that bugged me about it from day one was how high the gearing was. Here's this thing that was supposed to be an electric assist mountain bike, but it was impossible to use it like a regular mountain bike without electric assist (at least for me).
Let's consider the gear inches equation:
gear inches = wheel diameter * (front gear teeth / rear gear teeth)
- This bike has 27.5 x 2.3 tires, so call it 27.5" tire diameter.- front teeth are 15, but Bosch has roughly 2.5 times additional internal gearing, so 15 * 2.5 = 37.5 effective front teeth.
- rear cassette is 11-36, so 36 teeth for the granny gear.
gear inches = 27.5 * ( 37.5 / 36 )gear inches = 28.64 (roughly)
That's a little high for a mountain bike, from what I've seen this morning doing some research.

What if we change the gear ratio?

There are a few 14t front chainrings available for the Bosch mid drive. I ordered a Connex model. It seems highly recommended by various people on the internet.
I ordered tools to remove the front sprocket and rear cassette (lots of tools! but I like tools so that's fine).
What I'm having trouble figuring out is what I can/should use for a rear cassette, chain, and derailleur. The existing derailleur appears to be a Shimano Shadow (Deore?) XT Plus which appears to have about 3" between the pulleys on center.
At the extreme end, a 52t granny gear should give me:
gear inches = 27.5 * (14 * 2.5 / 52)gear inches = 18.50
which is just about perfect. If anything it might be a little low. 50t would also probably be fine with 19.25 gear inches.
I'm just not really a hard core bicycle guy so I'm not sure what will fit in my frame or stand up to the torque of the Bosch mid drive.
Can I safely go as low as 52t?
What should I buy? Any suggestions? Thanks!

 

[33red]

A heavier bike needs easy gearing. I bought a Haibike and at the shop before delivery i had the cassette 10 speeds 11-36 replaced by a 11-42 that was a smart move. The link is to a calculator
I guess you know your system has a 2.5 multiplier so your 14 teeth is like a 35
Sheldon Brown's Bicycle Gear Calculator

 

[Gary]

If i'm reading your post correctly you have a shimano 11 speed drivetrain?
If so. Just buy an 11-46 XT or SLX cassette (and probably a new chain with it)

With a 36T chainring and 11-46 11speed cassette on my emtb I rarely ever use the 37T sprocket nevermind the 46 while the motor is switched on.

While testing the One-up components groupset (36t ring and 11-50 cassette) I didn't ever need the 50t but it was quite nice to pedal up long hills in the 50t with the bike switched off.

Even in eco the assistance advantage on every emtb i've ever ridden is huge over a 25lb regular bike (ie. no motor)

disclaimer: I ride steep climbs but I ride non Ebikes a fair bit too and am fairly fit YMMV

 

[createthis]

If i'm reading your post correctly you have a shimano 11 speed drivetrain?

No, I'm pretty sure it's a 10 speed currently with a 15t front chainring and an 11-36t rear cassette.

One of the reasons why I am asking this here is because I'm not sure if an 11 speed cassette will fit my frame. My understanding is that usually there will be a spacer if the frame was designed to fit an 11. I guess I would have to remove the cassette to find out?

If so. Just buy an 11-46 XT or SLX cassette (and probably a new chain with it)

Why are you recommending a 46t? Seems like that would end up with 20.9 gear inches. Isn't that a little high for a regular mountain bike? The goal is to be able to have the motor off in all hill climbing situations and only use the assist if I want it.

 

[MattyB]

Why are you recommending a 46t? Seems like that would end up with 20.9 gear inches. Isn't that a little high for a regular mountain bike? The goal is to be able to have the motor off in all hill climbing situations and only use the assist if I want it.

If you really want to do that (and I'm not sure why tbh, but I guess everyone is different) then I suggest you are going to need one of the 12 speed SRAM or Shimano setups with at least 500% gearing. Ebikes are pretty heavy (especially the Bosch ones) and there is also the additional drag of the motor when switched off, so pedalling the unassisted is always going to be significantly harder - the lower the gear you have the more manageable that is going to be.

 

[Gary]

I recommended an 11-46 because it is the best value high quality option available. (sunrace are cheaper but they're shit. SRAM are more expensive)
I can climb fine on my Emtb switched off with an 11-46 (36t ring 27.5 tyres)
But I'm not you. I have no idea of your climbing ability or gearing preference. I'm just offering my solutio based on MY OWN riding.

An 11 speed shimano HG splined mtb cassette fits a standard 8 speed freehub with no spacers. As does an 8,9 or 10 speed cassette.
7 speed requires a spacer as I believe do 11speed road cassettes.
Some hubs (hope for one) require a slim spacer.

Sorry. I can't really be bothered working out gear inches (or even discussing them) . It's sort of irrelevant. Only YOU will know what gearing YOU require.
In reality there's not actually a great deal of difference between a 46 and a 50t sprocket though.

 

[createthis]

I recommended an 11-46 because it is the best value high quality option available. (sunrace are cheaper but they're shit. SRAM are more expensive)
I can climb fine on my Emtb switched off with an 11-46 (36t ring 27.5 tyres)
But I'm not you. I have no idea of your climbing ability or gearing preference. I'm just offering my solutio based on MY OWN riding.

I totally appreciate the feedback. I've never noticed significant drag from the motor at low speeds with the motor off, but then again I also have that 15t * 2.5 * 36t gearing so it isn't all that low, and I don't have a regular mountain bike for comparison. I'll take your word for it.

Regarding my level of physical fitness:

At the moment I am 38 years old and 5'9" at 190 lbs. I'm about 30-35 lbs overweight. I'm no superman. I'll need the lower gearing.

An 11 speed shimano HG splined mtb cassette fits a standard 8 speed freehub with no spacers. As does an 8,9 or 10 speed cassette.
7 speed requires a spacer as I believe do 11speed road cassettes.
Some hubs (hope for one) require a slim spacer.

I guess I'll take it apart and see.

 

[createthis]

If you really want to do that (and I'm not sure why tbh, but I guess everyone is different)

I'm not sure why anyone would want higher gearing on an e mountain bike.

If you use the bike like a real mountain bike and run out of juice, you're walking without the lower gearing. Just seems like a bad plan.

Sometimes I just want to work up a sweat exercising and don't need the motor for the trail, but maybe I want to turn it back on to get home on city streets quickly.

I don't know, I'm kind of confused why these aren't obvious use cases to everyone.

then I suggest you are going to need one of the 12 speed SRAM or Shimano setups with at least 500% gearing. Ebikes are pretty heavy (especially the Bosch ones) and there is also the additional drag of the motor when switched off, so pedalling the unassisted is always going to be significantly harder - the lower the gear you have the more manageable that is going to be.

So, something like this? Shimano XTR M9100 12 Speed Groupset, 10-51T Cassette - Brands Cycle and Fitness

Will that fit my existing frame?

 

[33red]

It allways comes to $. Presently you can find a 10 speeds cassette 11-46 with a new chain added to your smaller front the difference will be big with a reasonable investment. Check the calculator with before and after modifications.

 

[createthis]

It allways comes to $. Presently you can find a 10 speeds cassette 11-46 with a new chain added to your smaller front the difference will be big with a reasonable investment. Check the calculator with before and after modifications.

Can I use that with my existing derailleur (cassette and chain only) or do I need a new group set?

 

[33red]

Can I use that with my existing derailleur (cassette and chain only) or do I need a new group set?

If i fallowed correctly your shifter and derailleur can handle that modification. You can look at the part # on your derailleur, look at the site of the manufacturer and find the capacity. If not sure ask your local bike shop. If need be you can take your batery off to lower the weight and ride with no assist. It is a fresh start, new chain with new teeth front and rear. This will not mess with the chainline it is like just replacing worn parts.

 

[Gary]

At the moment I am 38 years old and 5'9" at 190 lbs. I'm about 30-35 lbs overweight. I'm no superman. I'll need the lower gearing.

I'm 11 years older. 2" taller and 15lb heavier. None of these stats give any indication of physical fitness nevermind climbing performance on a bike. .

 

[createthis]

I did some more research today. Apparently you can only shove an 11 or 12 speed cassette onto a 10 speed hub if you change the hub out in most cases.

My wheels are Easton Vice XLTs with X4 hubs. I don’t think they are 11 speed compatible, much less 12, but I’ve emailed the manufacturer to find out for sure.

 

[33red]

in my suggestion there is coming from ten going to ten, just one with more range

 

[Gary]

did some more research today. Apparently you can only shove an 11 or 12 speed cassette onto a 10 speed hub if you change the hub out in most cases.

An 8speed shimano HG freehub is exactly the same thing as a 10speed freehub.
8,9,10 and 11 speed HG mtb cassettes all fit.

 

[Gary]

12 speed is microspline (Shimano) or XD (SRAM)

 

[createthis]

An 8speed shimano HG freehub is exactly the same thing as a 10speed freehub.
8,9,10 and 11 speed HG mtb cassettes all fit.

Sorry for the delay in responding.

I bought a dedicated carbon non electric mountain bike and I wasn’t sure if I still wanted to improve the gearing on this emtb. Then my kids wanted to ride with me and commented on having to use electric assist on the trails to keep up. Ha. So I guess I’ll do this upgrade after all. Should be fun.

My connex chainring arrived along with the tools to do the job.

I just ordered a Shimano XT 11 speed 11-46 cassette, shifter, derailleur (long cage), and chain for about $280. We’ll see if it fits on my hub. You seem pretty confident it will, so I’m looking forward to this.

 

[JoshDwnHll]

Less gears are better, I had a 16t front sprocket with a 11-36 10speed on the back, I've changed the front sprocket to a sram 14t which made a huge difference and I've just managed to get a RADR cage to suit the Shimano saint derailleur which will allow me to run a 11-42 10 speed. In the future I will be looking at running a 11- 40 8 speed as I'm always shifting 2 or 3 gears at a time. With your set up you should be able to buy a Shimano 11-42 10speed and the 14t front sprocket and you will be fine.

 

[createthis]

Alright, I've been done with this project for a while, but it took me this long to edit the video and upload. I documented this entire procedure from start to finish. If you're curious, check it out: