Need Input for Trek Farley 7 Fat Bike Build

Joined
Aug 7, 2022
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17
My first time posting here and have been using the search function extensively to answer most of my research questions (thanks to all of you just for that!) but I'm still coming up short and/or looking for confirmation on my approach to building my first e-bike.

My plan is to use a 2022 trek Farley 7 fat bike as my platform to build a mid-drive BBSHD set up. I am 6 ft 2 in 215 lb so I'm using an XL size frame. My local terrain is steep, rocky, desert sand on one side and mountain dirt Sierra forests on the other. I'd like to be able to ride steep technical rocky/sandy climbs and singletrack in the summer and of course snow packed trails in the winter (I'm in Reno,NV so we get plenty of both)

I've only seen one other Trek Farley e-bike build (Fat Bike Rider) but I'm sure there are more out there. From what I understand the bottom bracket is wider than 120 mm so some modifications will be required to fit the locking ring. Also since the 2022 comes with a 1x12 drivetrain my concern is the chain line for the bigger cogs. I've seen several folks recommend swapping to a 1x8 setup (not sure if this is enough gearing for my size and >20% grade climbs?). Other gearing recommendations? I'm not sure but I'm hoping a 36T lekkie will fit so maybe we can use this as a basis for front gearing??

In any case, I should have the bike on hand in a couple weeks and then plan to start ordering parts. Since the frame is an XL I'm hoping to fit at least a 52V 20Ah battery in the frame.

I'm open to hearing any thoughts or things to consider for this build from you more experienced folks. I plan to start a build thread as well once I get going. Thanks!
 
One point: the number of gears you have isn't really relevant to the grade of climb and system/rider weight. The gear *ratio* you have available, specifically the lowest one, *is*.

If you need a significant range of speed vs torque, *then* the number of gears (or at least the ratio between the highest gear and the lowest one) may be relevant. ;)

So...given that, if you want to find out what kind of gearing you might need, you could go to the http://ebikes.ca/tools/simulator.html page and set it up to use a small "500w" to "1kw" hubmotor as a middrive (since they dont' ahve the BBS drives listed), and try different gear ratios until the system is able to climb the worst-case slope you have to deal with with the mass you ahve to deal with at the speed you need to go, without melting the motor. ;)

You can also use various online calculators to see how much power it takes to move the weight you have to up the grade you have at the speed you have to. Then assuming that is within the capability of the BBSHD, figure out the gearing you can use on that bike that will get you that speed for your wheel size.


Note that if you can't keep up the speed (because of traction, etc) for the gearing you use, you might have to shift to a lower gear so you don't overheat the motor trying to run it at a faster speed than it's able to put that power out for. So you might need at least one gear lower than the lowest you think you'll ever use, just in case.


Nuckingfuts said:
My first time posting here and have been using the search function extensively to answer most of my research questions (thanks to all of you just for that!) but I'm still coming up short and/or looking for confirmation on my approach to building my first e-bike.

My plan is to use a 2022 trek Farley 7 fat bike as my platform to build a mid-drive BBSHD set up. I am 6 ft 2 in 215 lb so I'm using an XL size frame. My local terrain is steep, rocky, desert sand on one side and mountain dirt Sierra forests on the other. I'd like to be able to ride steep technical rocky/sandy climbs and singletrack in the summer and of course snow packed trails in the winter (I'm in Reno,NV so we get plenty of both)

I've only seen one other Trek Farley e-bike build (Fat Bike Rider) but I'm sure there are more out there. From what I understand the bottom bracket is wider than 120 mm so some modifications will be required to fit the locking ring. Also since the 2022 comes with a 1x12 drivetrain my concern is the chain line for the bigger cogs. I've seen several folks recommend swapping to a 1x8 setup (not sure if this is enough gearing for my size and >20% grade climbs?). Other gearing recommendations? I'm not sure but I'm hoping a 36T lekkie will fit so maybe we can use this as a basis for front gearing??

In any case, I should have the bike on hand in a couple weeks and then plan to start ordering parts. Since the frame is an XL I'm hoping to fit at least a 52V 20Ah battery in the frame.

I'm open to hearing any thoughts or things to consider for this build from you more experienced folks. I plan to start a build thread as well once I get going. Thanks!
 
Good looking bike. Looking at a bunch of pics online, I think the one thing you may need to deal with is the chainring to chainstay clearance. Are you trying for the same chainline? Not many pics with a good angle, but the website says max chainring size is "1x: 32T, 2x: 22/36". Not sure what the 2x means unless the bike has a two chainring version.
https://cdn.shopify.com/s/files/1/2318/5263/products/BMT28334-9_2048x2048.jpg?v=1656338733
 
Thanks for the reply!
I'm certainly not looking to maintain the existing chain line for the 1x12. I'll have to wait until the bike comes in to know for sure but I'd like to shoot for a chain line that centers over either a 1x8 or 1x10 which will hopefully afford me a larger ring.

In this video, a fella has fitted a 40T bling ring on a 2021 Farley 5 (same frame as 2022) which has a 1x10 set up. Seems reasonable, am I overlooking anything I should be considering?

https://youtu.be/AoJuSpXzAfU
 
amberwolf said:
One point: the number of gears you have isn't really relevant to the grade of climb and system/rider weight. The gear *ratio* you have available, specifically the lowest one, *is*.

If you need a significant range of speed vs torque, *then* the number of gears (or at least the ratio between the highest gear and the lowest one) may be relevant. ;)

So...given that, if you want to find out what kind of gearing you might need, you could go to the http://ebikes.ca/tools/simulator.html page and set it up to use a small "500w" to "1kw" hubmotor as a middrive (since they dont' ahve the BBS drives listed), and try different gear ratios until the system is able to climb the worst-case slope you have to deal with with the mass you ahve to deal with at the speed you need to go, without melting the motor. ;)

You can also use various online calculators to see how much power it takes to move the weight you have to up the grade you have at the speed you have to. Then assuming that is within the capability of the BBSHD, figure out the gearing you can use on that bike that will get you that speed for your wheel size.


Note that if you can't keep up the speed (because of traction, etc) for the gearing you use, you might have to shift to a lower gear so you don't overheat the motor trying to run it at a faster speed than it's able to put that power out for. So you might need at least one gear lower than the lowest you think you'll ever use, just in case.

Great suggestions all around thank you!! An engineering approach is usually the most thoughtful. I'll take a look at the calc simulator you suggested.
 
Nuckingfuts said:
Thanks for the reply!
I'm certainly not looking to maintain the existing chain line for the 1x12. I'll have to wait until the bike comes in to know for sure but I'd like to shoot for a chain line that centers over either a 1x8 or 1x10 which will hopefully afford me a larger ring.

In this video, a fella has fitted a 40T bling ring on a 2021 Farley 5 (same frame as 2022) which has a 1x10 set up. Seems reasonable, am I overlooking anything I should be considering?

https://youtu.be/AoJuSpXzAfU

Good to have real examples :thumb: . Since the 40T has enough chainstay clearance, and since the 36T has less offset, it seem like it should have plenty of clearance.
 
I haven't started researching batteries yet but I keep hearing folks refer to different types (i.e. 25R, 30Q, 35E, GA, etc). Based on my intended purpose and terrain is there a specific type I should stick to? 

Is it safe to assume that Samsung, LG, and Panasonic are all good name brand batteries to go with?

I began to browse Em3ev at lunch today since several folks recommended them as a reputable supplier of quality batteries.

I plan to use the search this weekend to travel down that rabbit hole but I thought I'd ask in hopes you could point me in the right direction. Thanks!
 
Nuckingfuts said:
I haven't started researching batteries yet but I keep hearing folks refer to different types (i.e. 25R, 30Q, 35E, GA, etc). Based on my intended purpose and terrain is there a specific type I should stick to? 

Is it safe to assume that Samsung, LG, and Panasonic are all good name brand batteries to go with?

I began to browse Em3ev at lunch today since several folks recommended them as a reputable supplier of quality batteries.

I plan to use the search this weekend to travel down that rabbit hole but I thought I'd ask in hopes you could point me in the right direction. Thanks!
It depends on how much current you need for your setup. For the Samsung cells you mentioned, 35E stores the most energy, but 25R can supply the most current, 30Q is in between. So the trade off for more storage is less current capability and vice versa. The BBSHD isn't a hog when it comes to current, so you might opt for 30Q or 35E to have more energy/range. You don't need the super high current of a 25R, since you have gearing to make up for the amount of current you'd need to feed a direct drive motor to climb those hills. You can look at the data sheets for the cells you are considering to decide which is best, but I've noticed some cells types are harder to find currently. EM3EV is good since you can select which cells you end up with, rather than searching for a pack with those cells on the internet. They still may be impacted by supply though.
 
E-HP said:
It depends on how much current you need for your setup. For the Samsung cells you mentioned, 35E stores the most energy, but 25R can supply the most current, 30Q is in between. So the trade off for more storage is less current capability and vice versa. The BBSHD isn't a hog when it comes to current, so you might opt for 30Q or 35E to have more energy/range. You don't need the super high current of a 25R, since you have gearing to make up for the amount of current you'd need to feed a direct drive motor to climb those hills. You can look at the data sheets for the cells you are considering to decide which is best, but I've noticed some cells types are harder to find currently. EM3EV is good since you can select which cells you end up with, rather than searching for a pack with those cells on the internet. They still may be impacted by supply though.

Great information and thank you for the recommendation! I'll do some legwork of my own over the next couple days and circle back with some thoughts of my own on the topic. I appreciate the dialog!
 
Ok my eyes are dried out from all the reading on batteries and I feel like I've just scratched the surface. Of all the info floating around here (hard data, experience and opinions) it's clear as mud on which battery type to chose for my application.

I'm gathering that the 30Q sits somewhere between a 25R and 35E. Gives good high current supply (i.e. can handle 30A if I so desire for steep hill climbs) but at the cost of some range (which I'm ok with). With that said though I've seen some discussion comparing the 30Q vs MJ1. Here, https://endless-sphere.com/forums/viewtopic.php?t=108430

I haven't been able to find a 30Q option in stock (even if still listed as an option), maybe they're phasing these out and are no longer available?? What I am seeing from several suppliers is a MJ1 option.

So I guess I'm asking if I should sit tight in hopes the 30Q will be restocked or should I be looking at say the MJ1 or some other 'trending' battery for my application?
 
Nuckingfuts said:
Ok my eyes are dried out from all the reading on batteries and I feel like I've just scratched the surface. Of all the info floating around here (hard data, experience and opinions) it's clear as mud on which battery type to chose for my application.

I'm gathering that the 30Q sits somewhere between a 25R and 35E. Gives good high current supply (i.e. can handle 30A if I so desire for steep hill climbs) but at the cost of some range (which I'm ok with). With that said though I've seen some discussion comparing the 30Q vs MJ1. Here, https://endless-sphere.com/forums/viewtopic.php?t=108430

I haven't been able to find a 30Q option in stock (even if still listed as an option), maybe they're phasing these out and are no longer available?? What I am seeing from several suppliers is a MJ1 option.

So I guess I'm asking if I should sit tight in hopes the 30Q will be restocked or should I be looking at say the MJ1 or some other 'trending' battery for my application?

I haven't seen 30Qs available for a while, but MJ1's have a solid reputation.
 
Now that I've had a chance to get my head wrapped around all of the top cells and their specs (i.e. 25R, MJ1, 30Q, 35E, etc) I'm not so sure that the MJ1 will be a good fit. It has a higher internal resistance, much lower discharge c rate and one of the lowest discharge current ratings. Reputable yes but I want more amp capacity for sandy/loam hill climbs and desert runs.

With that said, the real problem as E-HP stated, is available cells. Em3ev only has GA in stock and has discontinued both the 30q and MJ1. I'm still waiting to hear what they plan to restock in the immediate future and if it's worth waiting for. Not much (if any) in stock from other reputable suppliers either. Unfortunately it looks like this build on hold unless you guys have any leads.
 
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