2022 M2S Ultra HT (hardtail fat-bike) review


100 mW
May 4, 2022
First post, so please bear with me. I'm late to the e-bike game, but have been watching for years. Long-time programmer and hardware hacker, moderately experienced cyclist. This is my first electric bicycle, but I've put hundreds of miles on electric rentals (typically 3-speed IGH). My spouse also has a Eunorau E-FAT-STEP, so I do also have some experience with that.

[edit]: this is the 100-mile review. 103 miles on the odometer.

Purchased: April 2022
Paid: $3200
Website: https://shop.m2sbikes.com
Rider: 6', 220lb (large frame), 75rpm nominal cadence.

Components not explicitly listed on site:
Motor: Bafang Ultra (M620) CAN bus
Battery: 48V Dorado 19.2AH, 2-pin, 2.1mm barrel
Chainring: 40T Bafang (website says 44, but it's incorrect)
Cassette: Shimano CS-HG500-10 11-34T
Derailleur: Shimano RD-M6000-SGS (36T max, Shadow+)

Packaging was "normal" - large box with styrofoam cutouts that contained the assembled frame and rear wheel. Front wheel, handlebars, and pedals removed. Shipping was about $150 to Denver via Old Dominion, and I was impatient so picked the delivery up at the terminal rather than wait for home delivery. Nothing eventful, but the box did have one hole knocked in it, which I've learned seems to be required damage. :roll: No damage to the actual bike, though. Fit and finish were fine, there was one downtube sticker that wasn't correctly adhered so I removed it, but it's otherwise clean from the factory.

My purpose was to acquire what's functionally an electric mule. For 6 months of the year, I spend as much time as possible afoot deep in the Colorado mountains, and was intrigued at the prospect of extending my reach with an electric bike. Since I hunt, it also would really help to be able to use a trailer to pull 100-800lb animals out of the woods. Speed is antithetical to these needs, but not power. This wasn't my first choice of bike, but the other vendor was struggling to ship in time for summer.

Presentation: The bike is H.E.A.V.Y. and huge compared to my normal squeeze (2010 Scott Aspect 20). I haven't weighed it but it seems to weigh at least the advertised 75lb. Everyone comments on how massive it is. The matte black paint, seat, geometry, etc. are all fine for me, but I'm not that picky about appearances. This thing seems to emit its own gravity, I think it wants to eat me. It certainly wants to eat anyone in front of me on a downhill coast.

Drivetrain: The drivetrain as installed is an exercise in compromise that I don't think makes anyone happy. At 11-34T the cassette is very (in my opinion) narrow and close for a 10-speed single MTB, and since the Deore derailleur maxes out at 36T, you're not swapping that out cheaply. The 40T chainring seems to try to make up up for that, but at the expense of what "everyone" seems to want, which is speed. As configured, the motor will spin the rear wheel at 47mph with no load, and I lost confidence at 40mph going downhill.

To bring things back down where I wanted, I bought a 104BCD spider from christinibicycles.com and a 30T RaceFace crank. I may still eventually go for an 11-50T 9-speed Box, but am at least now confident that I can ride the bike assistance-free in most terrain should the motor or battery fail. Or if I just really feel masochistic and want to self-power a 75lb bike. I was strongly considering sending the bike back until I made this change - now it maxes out at 35mph with me on, but most of the gearing keeps me well below 20mph, where I need it to be anyway.

The Deore derailleur is so-so. The Shadow+ feature is nice for rough off-road, but even when carefully tuned, compared to my 12yo SLX downshifting is sloppy and imprecise. This might be the next part to get replaced.

Range: Not fully tested yet, but I've been averaging 1-2% capacity per mile. At 80%, the onboard range calculator consistently suggests that I have 40 miles of range remaining (always in ECO 1).

Electronics: Interestingly enough, you can set the maximum speed and tire size on this bike via the DPC-18 display. Set the speed limit at 24mph or lower, and it limits the maximum power to 750W automatically. The maximum I can set is 62mph. You can also have the display show battery voltage or percentage, and power in watts or amps (acknowledging that only one of those is actually power). Changing any of this requires the bike to be stationary.

Another cool thing is that it attempts to calculate Kcal for a given trip - one would hope that they're basing this from the torque sensor readings, but as poor as Bafang's programming is, whether they actually do is anyone's guess.

Here we start to head downhill, but not for M2S' fault.

There are 10 assist modes, 5 each in ECO and SPORT, but for my riding thus far it's either on or off. Thanks to the surging, bucking initial thrust that the Bafang factory programming provides, I feel I have to turn assist all the way off when approaching technical, slow track or traffic intersections. It also keeps the crank turning a full rotation after you stop pedaling, despite having a torque sensor, helping ensure that unless you actively brake, you're going to be thrown into whatever abyss you were slowing to approach. Feathering one's way down a footpath is not this bike's strong suit. Smashing things may be.

My seat-of-the-pants measurement is that Bafang kept the 10% minimum amperage I see in the default UART configurations. On a 48V30A BMS, that means 150W, which is consistent with what the power meter shows. It's practically impossible to establish a steady cadence below 20mph (regardless of what crank is installed) unless there's significant wind, hill, or rolling resistance. Instead, the motor surges in and out, goosing your speed higher and higher. This behaves far more like a cadence sensor from a ratty city bike than it does the elegant, "bionic" feel that Bafang and friends would like you to believe it does. I think I would have been better off with a cadence sensor, to be perfectly honest.

My hope is that with heavier loads and steeper hills this will all smooth out some, but I'm not holding my breath. Bafang has no idea what "ECO" means, and while there is a time and place for that 10% jump, level 1 assistance is not it. It is my brash, semi-informed opinion that Bafang's programming is for casual riders or those with little interest in delicate, low-speed maneuvering.

I will not willingly purchase another post-UART Bafang without major programming changes. M2S has been gracious and helpful, but some of the support staff have obviously tired of my frustration with the motor.
Excellent report. Surprisingly, I haven't experienced the surging problem in seven years with a BBS02 or more probably, I'm too obtuse to notice it.
Thanks! I'm sure any number of factors could contribute to your not experiencing the surging, but it really feels like Bafang is focused more on impressing than on, say, finesse.

Took a heavy ride today, so thought I'd provide a more detailed report that isn't "100 miles in urban settings". I attempted to ride up Jones Pass outside of Empire, CO, and mostly made it but quit since the final leg still had a solid 20' wind ridge of snow still on it. I was only so prepared.

Trail: Jones Pass, CO
Temperature: 37-45ºF
Starting battery: 100%
Minimum observed battery: 41%
Ending battery: 47% (downhill recovery)
Combined weight: roughly 300lb (295 for bike and rider, plus day pack).
Distance: 7.5 miles
Min elevation: 10,427
Max elevation: 12,220
Net climb: 2,411 (multiple up+down)
Time: 2h5m
Surface: popcorn snow to slush
Average slope: 7º (15%)
Tire: Surly Knard 3.8" @ 25psi (WRONG choice)

I set out to ride what I assumed would be a muddy forestry road, and encounter snow about 1000 feet up. Since I'd previously put on the Surly tires for pavement pounding and was feeling lazy, I assumed they would be fine for the task. What I found was 100% snow, and the only reason I went as far as I did on them was because the first hour was cold enough to be riding on crust. I should have changed back to the 4.5 Kenda Juggernauts the bike came with.

The first and last 1/2 mile was somewhat vehicle accessible, but the remainder of riding was on snowcat tracks or open snow. For the initial climb to 12,150, the first 80% was in a mix of ECO 1 and ECO 2, the last 20% in ECO 3. 100% was in first gear (30T crank, 34T cassette), which strongly suggests that there's a lot of room for lower gearing. It also underscores just how much thrust the Ultra is throwing down even in ECO 1. For the last 3/4 mile I was fighting to climb 50% inclines at 12,000 feet on softening snow, but still pedaling right on up (ECO 3 in those conditions did start to induce some wheelspin).

After the first climb (~3 miles, 1700ft) I still had 68% battery remaining and an estimated 25mi range. I used the throttle to side-hill some steep snow I couldn't have pedaled, then descended to about 11,500ft to the floor of the western bowl. After resting, I decided to really test the motor and gearing, and climbed the northern cirque at an average of 8º (17%) with a maximum of 19º (45%) incline over 0.8 miles in 10 minutes. The motor performed admirably, even in the softening snow, although I had to take a handful of switchbacks to avoid getting stuck in ski and snowmobile ruts.

Finally, I took what my phone says was a 60º slope back down the bowl, 180mm brakes squealing the whole way. My skiing experience strongly suggests that it was far closer to 30 than 60, but I was definitely hanging my butt over the rear axle most of the way down. Zero complaints on the brakes for this bike. That descent did also make me regret that the fork only has 100mm of travel.

The ride was ridiculously fun. I still think the assist modes on the M620 motor are ridiculously overshot (note I never got past level 3). However, this represented probably one of the more extreme demands I'll ever make of this bike, and it handled better than I would have expected (particularly given the combined weight on snow). There is, in my estimation, zero chance that I could have made that ride with the stock 40T chainring, and it's still nearly over-geared.

The demands of the climb in snow definitely smoothed out the Ultra surge, but it was still very evident. I found myself starting from stops by feathering the throttle, because even ECO 1 was inducing wheelspin when the 150W punch hit on uphill starts.
Gratuitous photo? Gratuitous photo. It got a lot dirtier on the descent thanks to thawing conditions.


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Jones Pass was eventually a mortal wound to this bike. I went up last weekend to enjoy the snow again and despite having put the Kenda 4.5 tires back on at 10psi (backed by Tannus Armor), it started sinking fast.

A couple of miles in I was cranking hard up a 15-20% slope at max motor and human output when I heard that *snap* every cyclist learns to dread, and felt the drivetrain slip. I immediately stopped, assuming I'd broken the chain, but couldn't identify anything wrong, and the bike was behaving fine, so on we went. 6 miles later I was back at the truck with a nearly dead battery (producing 300-500w at most) and decided to take an Enduro hop over a rock. Settled my front tire against the rock, backpedaled, and started to pop over and got another *snap*. Still rode away fine, so I presumed that there was something weird with the pawl engagement in the motor.

Fast forward to this weekend, and a short grocery run produced crazy clicking and chain pulling, which would have likely ripped the derailleur into the frame if it didn't have the motor's freehub. I got home, but could replicate the issue 4/5 times by pedaling and gliding, and the noise was clearly coming from the rear hub. I disassembled said hub, and found shattered bits of 2/3 of the pawls and 2 ratchet teeth floating around in the grease. The cheap "Quando" hub wasn't up for the job, and yes - the front says "Quanta" while the rear says "Quando". Very Engrish.

M2S says it's under warranty, but hasn't yet specified what that will look like. At least the customer service is rational, but I'm seeing plenty of similar reports about Quando, suggesting that it's not very torque tolerant.
Since someone has asked in DM, I decided I should add here as well: after 400 pretty brutal high-altitude miles and two blown hubs, If I had it to do again, I wouldn't. I think the bike is probably par for the course of mediocre electric bikes made by slapping together the cheapest Chinesium possible and probably makes quite a few people happy, but I have higher standards.

M2S as a company has been fine, but the bike is a pig with weak components, and I'd probably lose my shirt selling it from the prices I see electric bikes not going for on my local boards. Therefore I'm going to try to make it as good as I can but will probably never trust it.

I bought the HT mainly because I wanted to get on an electric before summer to do a lot of backcountry travel, and the HT was available to ship and "close enough" to what I sought, or so I thought. I let a false sense of urgency overrule wisdom in this case.

After shattering teeth and pawls in the first hub I limited the motor to half-power, which kept it going through several camping trips and one hunt where it was leveraged in hot conditions (less rider weight) for long distance rather than rough terrain. It only made it 75% through the last hunt season where it saw actual hard use. This time the ratchet ring got spun in its race, stranding me miles from camp. Pushing a 75lb bike through snow over rough terrain is punishment all its own.

The drivetrain is the biggest shortfall here. Aside from the gearing ratio issues above, the manufacturer's maximum rider weight (275lb) on the original drivetrain translates to something like 320Nm on the hub. I suspect it's closer to 300Nm (and barely that) because with my 30T chainring, the motor at half power, and probably 235lb of rider, winter clothing, and day-pack (298Nm), the hubs are still failing. Oh - and the front fork is a steaming dog turd.

I'll be ultra [heh] honest: 750W is more than enough for me. I thought I needed 1500W, but with useful gearing there is nothing I want to do that I can't with half the power and 30% less weight. If I have the future budget to do it again right, I'll probably start with a proper weight-weenie fatty at 30lb or less with a decent 18-20 gear-inch drivetrain. I'll put the lightest 750W mid-drive I can on it and carry extra batteries. I don't want a sh*tty motorcycle, which is what this bike effectively is.

There's lots more to the story, but it's all anecdotal. Don't let cheap components fool you.
Thanks for the cautionary tale. I've ridden my BBS02-equipped hardtail for seven years off road with no maintenance to the motor and no problems, but possibly you're more aggressive than I am (although some of the rides were 15 or so miles and 3,000' elevation gain in pretty rough terrain). Maybe DIY is in your future.