Non-standard size frame options for e-Fat bikes with mid-drive motors

newheights

New Member
Region
USA
I am excited to get into e-bikes and fat bikes, and am new to both. Currently riding HT 29er MTB.

Researching around, it looks like there are a lot of options, but I am noticing many e-Fat bikes seem to only come in standard sizes (17" - 19").

Are there any e-Fat bikes you would recommend for taller (~6'4") and shorter (~5'5") riders?

For reference, my current MTB has ~20.5" frame with 33.5" standover height and rides OK, sometimes feels a bit small as I have to jack the seat up higher than I would otherwise like to get comfortable leg extension
Other rider has a 15" MTB and feels it is OK, but perhaps a bit on the smaller side.
Neither of us seem like we would fit comfortably on a 17" or 19" frame.

So far what I have come up with for the larger frame is the M2S All Terrain Ultra HT (unfortunately out of stock currently) with a 21" frame. (https://shop.m2sbikes.com/collections/all-terrain-electric-bike-series/products/all-terrain-ultra-ht)
- in addition to lack of availability, the tire width is limited to 4.5". I had hoped to be able to upgrade to 5" for snow in the future, but perhaps 4.5 vs 5 is not a big deal?

For smaller frame, it seems the Bolton Sabre with step thru (https://boltonebikes.com/products/sabre), also unfortunately out of stock currently, or potentially the Biktrix Stunner X (https://www.biktrix.com/pages/stunner-x-details) might work.
- downside here is the cruiser geometry, really would prefer something better for trails, though maybe that is not a big deal when using a pedal assisted bike?
- the Biktrix it appears uses the BBS02, which I had read does not handle slow technical steep uphill as well as BBSHD or ultra-max
- not sure on the max tire size yet

For shorter rider, might it be necessary to go down to 24" tires, and does that negatively impact the ability to ride rough trails or handle snow?

I would consider doing a conversion, though would prefer a bike that comes prebuilt and tuned. Still, had trouble finding appropriate sized frames that weren't fairly pricey to start, or out of stock. That also would limit it to BBSHD instead of ultra-max, which power wise I think is fine but means no torque sensing, and a slightly more exposed motor.

Any thoughts regarding other options that would work well, or on if any of the bikes I listed are good/bad ideas? I'll list some specifics of how we plan to use these if that informs the recommendations.

Our use case will be
- predominantly ~10-20 mile rides on flowy single track / forest service roads
- rides of 40-50 miles on occasion
- very hilly, lots of up and down, shortest ride we do currently has ~1,200 feet of climbing, but some rides we would like to do would climb 5,000 ft +
- some very steep grades (old logging roads) that go for 0.5-2 miles
- winter use including snow, mostly on graded, drive-able (though gated off to cars in winter) dirt or paved roads, to access back country. Good traction (which I think means wide tires?) particularly important for long descent
- otherwise will mostly be dirt vs mud and gravel when not at elevation
- occasionally heavy towing, trailer vs paniers, with camping gear, backcountry skis, or dogs
- mostly plan to use low level pedal assist to augment our own efforts, but do want a throttle for starting from a stop on hill or in case of injury/exhaustion while out

Based on that and my initial research, some items I thought sounded important were
- mid drive motor, particularly for slow steep climbs under load (preferably BBSHD and I think ultra-max also handles this ok?), from my reading, BBS02 and especially hub drive motors would not be good options here
- option for wide fat tires, for good snow traction
- reliable brakes that can handle a 15 mile 5,000 ft descent
 

AHicks

Well-Known Member
Region
USA
City
Snow Bird - Summer S.E. Michigan, Winter Gulf Coast North Central Fl.
I would likely be shopping for an Ultra with a pretty good size battery. Rize, M2S, and Biktrix come to mind. 40-50 mile rides on an Ultra powered fatty might be tricky. I can get 35ish miles without too much trouble in the hilly area we spend a lot of time in - but I'm 300lbs riding a Rize RX Pro with a 19.2 ah battery.
 

newheights

New Member
Region
USA
I would likely be shopping for an Ultra with a pretty good size battery. Rize, M2S, and Biktrix come to mind. 40-50 mile rides on an Ultra powered fatty might be tricky. I can get 35ish miles without too much trouble in the hilly area we spend a lot of time in - but I'm 300lbs riding a Rize RX Pro with a 19.2 ah battery.
Thanks that is helpful info. I am not too stressed about the range, I plan to play around and see how much I can get using low level pedal assist. I would probably buy a second battery if I was consistently running into issues, but rides over 20-30 miles would be an exception to the norm.

How do you like Rize as a company?
How do you like the RX Pro for fit? and how tall are you if you don't mind sharing.

Thanks
 

Timpo

Well-Known Member
I am excited to get into e-bikes and fat bikes, and am new to both. Currently riding HT 29er MTB.

Researching around, it looks like there are a lot of options, but I am noticing many e-Fat bikes seem to only come in standard sizes (17" - 19").

Are there any e-Fat bikes you would recommend for taller (~6'4") and shorter (~5'5") riders?

For reference, my current MTB has ~20.5" frame with 33.5" standover height and rides OK, sometimes feels a bit small as I have to jack the seat up higher than I would otherwise like to get comfortable leg extension
Other rider has a 15" MTB and feels it is OK, but perhaps a bit on the smaller side.
Neither of us seem like we would fit comfortably on a 17" or 19" frame.

So far what I have come up with for the larger frame is the M2S All Terrain Ultra HT (unfortunately out of stock currently) with a 21" frame. (https://shop.m2sbikes.com/collections/all-terrain-electric-bike-series/products/all-terrain-ultra-ht)
- in addition to lack of availability, the tire width is limited to 4.5". I had hoped to be able to upgrade to 5" for snow in the future, but perhaps 4.5 vs 5 is not a big deal?

For smaller frame, it seems the Bolton Sabre with step thru (https://boltonebikes.com/products/sabre), also unfortunately out of stock currently, or potentially the Biktrix Stunner X (https://www.biktrix.com/pages/stunner-x-details) might work.
- downside here is the cruiser geometry, really would prefer something better for trails, though maybe that is not a big deal when using a pedal assisted bike?
- the Biktrix it appears uses the BBS02, which I had read does not handle slow technical steep uphill as well as BBSHD or ultra-max
- not sure on the max tire size yet

For shorter rider, might it be necessary to go down to 24" tires, and does that negatively impact the ability to ride rough trails or handle snow?

I would consider doing a conversion, though would prefer a bike that comes prebuilt and tuned. Still, had trouble finding appropriate sized frames that weren't fairly pricey to start, or out of stock. That also would limit it to BBSHD instead of ultra-max, which power wise I think is fine but means no torque sensing, and a slightly more exposed motor.

Any thoughts regarding other options that would work well, or on if any of the bikes I listed are good/bad ideas? I'll list some specifics of how we plan to use these if that informs the recommendations.

Our use case will be
- predominantly ~10-20 mile rides on flowy single track / forest service roads
- rides of 40-50 miles on occasion
- very hilly, lots of up and down, shortest ride we do currently has ~1,200 feet of climbing, but some rides we would like to do would climb 5,000 ft +
- some very steep grades (old logging roads) that go for 0.5-2 miles
- winter use including snow, mostly on graded, drive-able (though gated off to cars in winter) dirt or paved roads, to access back country. Good traction (which I think means wide tires?) particularly important for long descent
- otherwise will mostly be dirt vs mud and gravel when not at elevation
- occasionally heavy towing, trailer vs paniers, with camping gear, backcountry skis, or dogs
- mostly plan to use low level pedal assist to augment our own efforts, but do want a throttle for starting from a stop on hill or in case of injury/exhaustion while out

Based on that and my initial research, some items I thought sounded important were
- mid drive motor, particularly for slow steep climbs under load (preferably BBSHD and I think ultra-max also handles this ok?), from my reading, BBS02 and especially hub drive motors would not be good options here
- option for wide fat tires, for good snow traction
- reliable brakes that can handle a 15 mile 5,000 ft descent
How much money are you willing to spend?

WattWagons offer a frame in 22", although I'm not sure if that's necessary because Tora Harris (owner of Juiced Bikes) is 6"3' and he can ride Juiced RipCurrnt S just fine, as far as I can see from YouTube video.

WattWagons is generally open to customization (for additional cost, of course) and if you want 26 x 5.0 tires I imagine they can do that.
It's a 750W Class 2 bike by default, but you can go all the way up to 2300W nominal, 3000W max with Archon X1 controller.
 

newheights

New Member
Region
USA
How much money are you willing to spend?

WattWagons offer a frame in 22", although I'm not sure if that's necessary because Tora Harris (owner of Juiced Bikes) is 6"3' and he can ride Juiced RipCurrnt S just fine, as far as I can see from YouTube video.

WattWagons is generally open to customization (for additional cost, of course) and if you want 26 x 5.0 tires I imagine they can do that.
It's a 750W Class 2 bike by default, but you can go all the way up to 2300W nominal, 3000W max with Archon X1 controller.
I was hoping to get something in the $2.5-3k range. I am not certain the quality of bike/components I would get for that (ie M2S All Terrain Ultra HT). I could push the budget up to about $4k but would have a hard time going beyond that for now. I have heard great things about WW, but currently a bit out of price range.

The Juiced RipCurrent S actually looks pretty good for what I want, I'll have to dig around for some reviews. And it is in stock.
EDIT - missed that it's a hub drive motor, so probably will give this one a skip. But good to know 20" frame was comfortably for large riders.

Generally, do I want a similar fit for fat bike as for MTB? I may be making too big a deal out of this, particularly if it is a more upright geometry anyways, meaning I could crank the seat post up and won't feel too stretched out.
 
Last edited:

Timpo

Well-Known Member
I was hoping to get something in the $2.5-3k range. I am not certain the quality of bike/components I would get for that (ie M2S All Terrain Ultra HT). I could push the budget up to about $4k but would have a hard time going beyond that for now. I have heard great things about WW, but currently a bit out of price range.

The Juiced RipCurrent S actually looks pretty good for what I want, I'll have to dig around for some reviews. And it is in stock.
EDIT - missed that it's a hub drive motor, so probably will give this one a skip. But good to know 20" frame was comfortably for large riders.

Generally, do I want a similar fit for fat bike as for MTB? I may be making too big a deal out of this, particularly if it is a more upright geometry anyways, meaning I could crank the seat post up and won't feel too stretched out.
Well I don't know.. don't you want a 26 x 5.0 tires though?
Not sure if RipCurrent S can fit that tire, maybe it can.

Do you have a normal fat bike that you already like?
Have you thought about conversion?

CYC X1 seems to be popular for conversion. It's very compact but has lots of torque.
Seems a bit overkill though, personally I would not get it. But the motor is so small :oops:

 

Timpo

Well-Known Member
This one?

It's available on Alibaba, but Bolton has one too.
 

Timpo

Well-Known Member
Sondors has 26 x 4.9

That's pretty big
 

AHicks

Well-Known Member
Region
USA
City
Snow Bird - Summer S.E. Michigan, Winter Gulf Coast North Central Fl.
Thanks that is helpful info. I am not too stressed about the range, I plan to play around and see how much I can get using low level pedal assist. I would probably buy a second battery if I was consistently running into issues, but rides over 20-30 miles would be an exception to the norm.

How do you like Rize as a company?
How do you like the RX Pro for fit? and how tall are you if you don't mind sharing.

Thanks
Should have mentioned I ride with minimum amounts of power assist. I start pedaling when I leave the house, and stop when speeds get up over 15mph going down hill. PAS 1 as a rule, and increasing as necessary for hills. RARELY do I use PAS 4, and I used PAS 5 once just to see if it worked.

I think you'll find the 26x4" tires are plenty, especially for use as a hybrid, or, if battery mileage is of ANY concern. The 4" are already pretty draggy.... To even have a chance at the kind of range you're talking about, you'll need to pump them up to near max. capacity.
 

newheights

New Member
Region
USA
Well I don't know.. don't you want a 26 x 5.0 tires though?
Not sure if RipCurrent S can fit that tire, maybe it can.

Do you have a normal fat bike that you already like?
Have you thought about conversion?

CYC X1 seems to be popular for conversion. It's very compact but has lots of torque.
Seems a bit overkill though, personally I would not get it. But the motor is so small :oops:


I think I will have to sacrifice something, so not fitting 5" tires is not a strict no go, but it would be nice.

The warthog you linked looks good. I researched it a fair bit, it does have the twist throttle unfortunately which I am not a fan of I'd rather be covering the rear brake for motor cutoff while using a left thumb throttle. Maybe I could add a thumb throttle and disconnect the twist one, but the cables route internally so I am not sure. It is also a behemoth of a bike in appearance, hah, which I suppose is fine but not loving the aesthetics. I wonder if that top tube would cause some straddle injuries, if you fell far enough forward it's at or above the seat height. The batteries seem like they may be proprietary to fit the cutouts, which I worry a bit about for future-proof-ness in case they stop making them or something. Probably could rig up a new connector to a generic battery though.

I found HPC Titan as well, but that is more expensive than I would like, though it does appear well built.

I have not heard good things about the Sondors, specifically I saw in a video somewhere the balance is poorly centered and it is tough to ride on trails because of it. The XS is a hub drive which I had planned to avoid in favor of mid drive. They are releasing some mid drive units. The rockstar actually looks like a pretty good price for what you get, but shipping is estimated for August, and I would suspect there is a high chance it could get delayed further. I am not sure on the sizing. It only comes in one size, which is not encouraging. The motor comes limited to 750W even though it is the M620 Ultra max, which is actually likely fine for my uses, and I am sure within the year of shipping someone will have a way to mod it.

Quietkat, Rambo, Backou seem to have some great options if you are not cost conscious, will not work for my budget though.

Biktrix seems like they make quality bikes but the size I think won't work. Their largest frame on the ultra motor bikes currently seems to be 18.5", I am having a hard time getting the exact geometry specs, but what I have been emailed is not encouraging, as they have shorter than usual crank arms at 5.5", and their max seat height is around 40" measured from ground to seat.

I would definitely do a conversion and may need to go that route. I had a slight preference for a branded e-bike from NA seller for post-sale support. I have never ridden fat bikes before, and don't have one in particular in mind. There seems to be low supply of XL frames for those as well. Framed bikes Minnesota was recommended, but they are out of stock. A used Surly might work, but I don't see any available. Mongoose seems too small. BikesDirect has some items in stock, but fairly limited, and unclear when the shipping would be. Even those labeled as in stock have a warning you have to click through that you are pre-ordering ... http://www.bikesdirect.com/products/fat-bikes.htm I don't actually see a bike for reasonable price that has frame size 20" with fat (4.5" +) tires. They're either smaller frames, or the 27.5 x 2.8" tires.
 

newheights

New Member
Region
USA
I would likely be shopping for an Ultra with a pretty good size battery. Rize, M2S, and Biktrix come to mind. 40-50 mile rides on an Ultra powered fatty might be tricky. I can get 35ish miles without too much trouble in the hilly area we spend a lot of time in - but I'm 300lbs riding a Rize RX Pro with a 19.2 ah battery.
I was looking at the RX Pro some more, the website says it's a 17" frame. Is that accurate, and how does it fit for height?
 

Timpo

Well-Known Member
Well if you're on budget, you could buy one directly from China, rather than buying one from US based companies.

 

AHicks

Well-Known Member
Region
USA
City
Snow Bird - Summer S.E. Michigan, Winter Gulf Coast North Central Fl.
I was looking at the RX Pro some more, the website says it's a 17" frame. Is that accurate, and how does it fit for height?
The fat tires make the bike pretty tall, noticeably so, and at 6'2", I have no trouble getting the seat high enough for good leg extension. To reach the ground, I am tippy toe for sure when seated.....

The Rize is actually similar to a 29'er I used to ride a few years back. I would not want anything any taller for sure!