Soma B-Side V.2 Belt Drive BBS02 750W/48V Custom Build

[RusticoRay]

How is your igh holding up?

[Rider]

Only had it out on two riders under human power so far. Love the gearing and how the IGH operates. I have it attached to a SRAM X9 3spd derailleur shifter. It slams the up gears beautifully, but the downshifts require a slight pedal hesitation to be easy. Basically riding it as a 40lb. single speed in 2nd under human power, only hitting 3rd on declines and tailwinds. The bike smokes in 3rd with a tailwind under human power only! Guessing I will be running this 750W monster on one of the lowest settings once I get a battery.

[Rider]

Took it out for another ~20 mile shakedown ride and everything worked perfectly. Gearing continues to be wonderful for pedaling without power. Played it smart and went into the wind for the first 10 miles, so the return would be down wind. 3rd gear rocks down wind, but until I hook up a battery to the display I don't know what my speeds are yet.

Glad I relocated the display to a stem cap GoPro mount below the handlebar topline. I already crashed my new ride the second time out. Turned into a four tier stair drop forgetting I was not on my full suspension Hightower with seat post dropper. Made it to the bottom, but the final impact without my weight back low behind the seat threw me over the bars onto the cement. Only scuffs on the elbows and knees, plus a bent brake lever that I bent back today. Whew! Close call...



The display didn't get touched in its' new position.

The Ibera Mini Commuter custom rack is out getting welded. I ended up using adjustable aluminum side bars and front frame mounts from a cheap Schwinn alloy rack. Those got mounted to the two flat tabs on the sides of the short stubby Ibera rack tray. This puts the battery bag on the rack low and forward, almost in a large seat bag position. Pictures soon...

[RusticoRay]

Rider I'm waiting on my wheel with the cs-rk3 to show up. I'm having to replace my nexxus 3 cause of a high gear slip and knocking that happens quite often. Of course I welded the csx cog on it, not recommending that process. Like your ride. Hoping to get some milage on the new hub and check back soon. Peace

[Rider]

Here's a sneak peek at the modified mini bag rack with all the components while the paint cures. I thinned it out by removing even more of the web structure that went around the original seatpost clamp bar and beefed up the center section while keeping tire clearance in the center. The straight round bar welded on the front rests on the top adjustable frame mounts to support the minimum 12lbs. of battery and bag that will always be on the rack when riding under power.

[Rider]

Got the rack on the bike. In this close up you can see how the bar stock added to the front sits on the two front frame mounts to support the eventual weight it will be carrying.

Here's the whole bike basically done with rack and bottle cages and with battery/storage bag and dual large water bottles for those long range rides.

[Rider]

Love that stealthy look. Hard to tell it's an E-bike from this angle. Looks like any other belt drive bicycle with a rack and bag.

[APailthorp]

Running my belt and CS-RK3 off the BBSHD with 55x24. Cruises real nice, have about 150 miles on it so far. With this gearing, the bike definitely needs the motor. I rode it 50x28 for a bit, then electrified it, then tried 50x24. Finally I decided to go to 55x24, although that means keep your battery charged for sure. Cruising in third with a nice cadence at about 24MPH, stop pedalling at about 27 MPH, tops out motor only about 29-30 MPH on the flat.

[Rider]

Good to know. Can you give me cruising in 3rd at a nice cadence and top speed for the 50x28 and 50x24? What wheel and tire size? Also, do you know how much faster the RPM of the BBSHD is compared to the BBS02? Thx.

RATIOS:
50x28=1.78 (2nd), 1.78*1.33=2.37 (3rd)
50x24=2.08 (2nd), 2.08*1.33=2.77 (3rd)
55x24=2.29 (2nd), 2.29*1.33=3.04 (3rd)

[Rider]

I think it is important to give general build costs so others can better estimate what their project will cost up front. I got some pretty good deals on some of the parts for this build, yet the total cost still came to $3,800 (the equivalent of $3,500 plus 8% sales tax). That doesn’t include any personal labor cost, but does include $200 in: wheel build, frame prep and welding costs that I paid others for. The custom frame belt drive bike itself without any electronic components came to $2,300 and all the electronic components: BBS02 750W/48V, 21Ah Panasonic GA battery, smart 80% or 100%, 3A or 5A charger, rear rack and bag came to $1,500.

What this gives over a pre-built of equal cost is complete customization to ones specific wants and needs that generally have to be “settled on” with all the manufactured E-bikes. In addition, a component build allows you to replace and/or repair parts yourself; especially the motor and battery stuff which can be costly and similar to automotive repairs. And we must not forget the "throttle option" that is almost nonexistent on manufactured models. Furthermore, you can always convert a custom build back to a regular bicycle and move the motor and battery stuff to another build down the road if desired.

Above and beyond that, you would be hard pressed to find a Gates belt drive 750W/48V throttle option 21Ah E-bike with this level of quality components for $3,500. You can build something close for much less if you find a bike that has all the other components that you specifically want. For me the 3spd IGH and belt drive were key components that I really wanted to try.

Once my monster sized Luna battery and charger arrives, I will post up my impressions of the riding experience under different power levels, along with speeds with this Class 1-2 limited rather low gearing and resulting mileage ranges.

It has been a fun build. I look forward to years of riding this with very limited maintenance, just hours of joyful bliss in the outdoors.

Cheers all!

[Rider]

WHOA! The 21Ah monster battery and smart charger arrived today. It came from Luna very well packaged.

The pictures show the Ibera Mini Commuter bag, Luna 4” X 6” X 8” 21Ah Soft-Pack Battery and Smart Charger (1-5Amp variable plus 80% - 90% - 100% charge options). The Ibera bag has padding sewn into the sides and bottom already for good protection. This rectangle size is a perfect fit (in front of the rear mount hump) on all sides. There is also additional room for storage above it. Even the rather large battery charger fits in with room to spare if you wanted to have it with you.

I know what my weekend project will be. Should be powering up and riding tomorrow…

[Rider]

Now that the Soma eMTB is up and running, the SC Hightower can once again be delegated to off-road MTB duty only, which is what it is designed for. That means I can return my SQlab 311 bars with Ergon GP5 bar ends mounted in front of the grips as “inner bars” on this new trail and touring eMTB for comfortable hand positions on those long rides. The SC Hightower will get its’ original semi-flat bars back for cutting up the single track. While switching the bars and stem I installed the throttle as well.


I spent the morning getting all the handlebar goodies in just the right position, while I topped off the battery using 3amps on the smart charger up to 54V. I think it shuts off automatically at 54.6V, but I was ready to go when it was at 54V, so I unplugged it. You can see how the 8” X 6” X 4” 21Ah battery fits nicely into the Ibera Mini Commuter bag with room to spare for other things.


I made an effort to run all the wires without zip-ties if possible and hiding the zip-ties I had to use the best I could. This involved using some special little full housing shifter cable “conversion mounts” that attach to normal cable stops and snap around the cable housing in three places on the bike. The only place that I was unable to somewhat hide the zip-ties is on the left lower chain stay wiring for the magnetic sensor there. For now I just ran the red and black battery discharge wires into the front of the bag at the end of the zipper. I plan to cover them with a black wire housing of some type in the future.

[Rider]

It turns out something was amiss during the "around the neighborhood” test rides. I should know better by now that “parking lot” test rides are not reality. Don’t know what happen, but it could be that the changes to the settings on the display don’t get applied unless you power the system off and reboot it. I didn’t do that, so I may have been running it at 36V instead of 48V or possibly a new motor needs a little break-in time (who knows?). Anyhow, here’s my first real world test ride which is very different than what I had originally posted. I have now <DELETED> that and posted this.

Because I don’t know what the range will be with this 21Ah battery pack, I planned my first ride to be 20 miles out and 20 miles back for a total of 40 miles. That should be easily within its’ range and gave me a good size range cushion just in case I’m wrong. I helmeted up, put on my gel gloves and off I went to catch the San Gabriel riverbed trail to Sunset Beach to start. I’m about 5 miles from the paved trail and have a nice bike lane street to get there.

The first big WOW was right off the bat I noticed the motor had much more power than it did over the weekend (?). I thought maybe it was the full 54V charge at first, but as I increased the power levels it became clear this 750W 1-horser wants to run! Real world tests are so wonderful and eye opening.

I can now say right up front that the gearing is spot on. The 50T X 28T 1:1 2^nd gear used as a first gear on level 2 of 5 takes you from a standing stop with ease. A quick shift to 3^rd (used as my second) and it’s straight to about 15-16mph cruising speed. You can start with a simple push of the pedal and power comes on quickly (no waiting for the magnetic sensor on the rear wheel) or you can just hit the throttle for a second, let off, shift into 3^rd and start pedaling.

Level 2 of 5 is the sweet spot on the 1-5 setting. Bump it up to level 3 and hold on! She will move right to 19mph and at a fast cadence; a little too fast for me. You can ghost pedal and she holds 18-19mph too. Levels 4 and 5 are really too fast of a cadence for me to add much watts with my legs, but she will hit 24mph without a problem. Once again you can ghost pedal or use the throttle and cruise at 24mph. Personally I don’t “need” to go that fast and setting the 20mph speed assist limit in the advance settings on the display really wouldn’t bother me at all.

The best usable levels are 2-3 of 5. I’m sure Level 1 would be fine for certain slower rides as well, but I didn’t spend much time experimenting with it on this ride. Level 2 for normal riding with a cruising speed of 15-16mph, and a bump up to level 3 when you hit a hill or want to move quickly at up to 19mph is the initial sweet spot or me. I’d actually like a Level 2.5. On my next ride I will change the power level range to 1-9 and see if I can find a slightly slower cadence with a speed between 16-19mph.

The second big WOW is range. Below is a picture of the display readout after 40.9 mile trip.

As you can see I only used about 1/3 of the battery supply; 2/3 is still green. I won’t put money on a 120 mile range, but I think 100 miles might be doable. I didn’t conserve AT ALL on this ride. I was using the throttle, ghost pedaling and playing with Level‘s 3-5 in different situations. A couple times I pegged it to Level 5 and hit the throttle for about 2-3 miles, then started pedaling as fast as I could for another several miles to see what I could get out of her. 24.5-25mph with my legs spinning out of control is about it for this old man. I did hit over 28mph, but for the life of me I can’t remember where that was. Best guess would have to be on a downhill somewhere, maybe an over or under pass.

On one of my Level 5 pushes for about a 5 mile stretch, I kept hearing little clicking noises behind me. Initially I was concerned the rear IGH was acting up with all those watts and me pedaling my heart out, but once I slowed to exit the trail a beautiful safety orange carbon roadie pulled around me and thanked me for the lift. He was drafting me for about 5 miles at 24mph with ease. He didn’t even look winded.

My initial real world test ride makes me think I hit the bull’s eye with the gearing for my needs. It cruises at my desired mph in Level 2 of 5 in 3^rd gear. It can easily go much faster with or without the throttle if needed. A simple bump to Level 3 allows you to climb right up overpasses with ease. It appears the amazing power will easily climb a wall in first gear, but that test will have to wait for my first off-road trail ride.

This build has surpassed my expectations with just one real world ride. I can now ride to the beach, instead of removing the battery and loading the heavy eMTB onto the roof rack on my car, then unloading it to ride; only to have to lug it up on the roof again for the drive home and then unload it again once there too. Riding the bike to the trail without the car will also pay for lunch each day I go ride with the gasoline saved. How great is that?!

[Rider]

After adjusting the Level setting to 9, I went for a 30 mile ride today WITHOUT RECHARGING THE BATTERY (so this is on top of the 41 mile ride already completed on the first full charge) and I still have 43.2V of charge after a total of 70.6 miles. Sweet!



I’m really liking these range figures I’m getting. Both outings were not eco rides at all. I continue to play with the higher level power settings and the throttle. Today I rode from my home over to the Fullerton Loop trail (semi-off-road) and did a section of the loop with some climbing on steep dirt.

The gearing remains spot on (for me). Low gear can climb the steep stuff I ride and I was able to do it without having to hit the throttle override. The PAS never cut out on the climbs I did today. I just bumped up the power level after shifting down to 1st gear.

With the Level setting on 1-9, I found Levels 3-6 to be the most useful. Level 5-6 of 9 seems to be between Level 2-3 of 5, which is slightly different than their respective fractions would suggest, but this could be because the battery is below the 48V threshold.

Here is a dismal fraction breakdown for Level settings 1-9 and 1-5:

LEVEL 1-9------LEVEL 1-5

1/9 = 0.111
--------------------1/5 = 0.200
2/9 = 0.222
3/9 = 0.333
--------------------2/5 = 0.400
4/9 = 0.444
5/9 = 0.556
--------------------3/5 = 0.600
6/9 =0.667
7/9 = 0.778
--------------------4/5 = 0.800
8/9 = 0.889
9/9 = 1.000------5/5 = 1.000

Although Level 4-5 of 9 are between the dismal fraction numbers of 2-3 of 5, with the starting battery level of 47.6V, Level 5-6 of 9 felt more like they were between 2-3 of 5 to me and my speeds seemed to confirm that. At this point I guess it is worth mentioning that as the battery charge volts decrease, the power applied seems to reduce (based on my observation only). I guess that makes sense, because I am now below the 48V setting on the display and the battery has less than that voltage to apply.

Because of the greater fine tuning the Level settings on 1-9 provide, I will be leaving it on 1-9 going forward. After going into the “advanced” settings, I noted that the speed limiter was set to 25mph when I got it. I changed that to 20mph and didn’t mind it at all. So this eMTB is now setup as a Class 2 California Electric Bicycle with speed limited to 20mph and optional throttle.

The initial range is very impressive to me. Most of today’s ride was at Level 6 of 9, so I’m not babying this 1-horse beast. I can’t imagine the need for a BBSHD 1000W+ motor; at least not for how I ride my E-bike.

[Rider]

Went out this morning to drain the last miles out of this first charge after looking up the battery voltage drop controller cutoff on Luna’s site; it states 39V. I rode at Level 5 of 9 and got to 74 miles before the cultch on the motor started clicking in and out now and then in 3rd gear. At that point I changed power Level 4 of 9 and all was well, but headed home to call the first battery drain test good there. This is the display state at the end of the ride.



I’m going go with a reliable range of 75 miles under normal multi-use and power level riding, because this first test had way more high level and throttle use than I would normally use. It’s worth noting too that the display states 42.0V left and there is still assist left in it. I noticed if I put the bike in the 2nd gear 1:1 and pedal at 10mph it only uses 45-50V without any clutch chatter. I bet it will go much further at the lower speed if you happened to be miles from your destination, so there is no real range anxiety even if you can’t ride at 16mph after 75 miles.

A low level power assist range test will be much more difficult to do. If I ride in only Level 1-3 of 9 I’d probably have to go on 3 or 4 long rides to drain it and likely about 100 miles like Luna states the battery will do, depending on power level and the amount you pedal.

Back on the charger it goes for a second 100% 3 amp charge…

[Rider]

Battery test number two was planned out for about 60 miles. Now the Level setting is on 1-9 and I did most of the ride on 5-6 of 9, with a few bump ups for hills and drafting a fast roadie and a reduction to 4 of 9 through some congested beach boardwalk areas. Took the San Gabriel riverbed trail to Sunset Beach, then headed south through Bolsa Chica, Huntington and Newport Beach; all the way out to the tip of the Balboa Peninsula at the Wedge. That was 30 miles, all into a nasty headwind.

Next I back tracked through Newport Beach to the Santa Ana riverbed trail and headed inland towards Angel Stadium. Just a few miles away from the beach I started to notice a sporadic swish-swish-swish noise now and then. I thought maybe something on the new BBS02 didn’t get properly greased during manufacturing and I pushed on. Then it seemed to get worse and my concern changed to something internal wasn’t right.

I started trying to debug it on the fly. I noticed as I stopped pedaling the noise continued for a short period that was the same amount as the motor assist. I thought damn, there is a motor problem and I’m going to have to pull over and call a friend for a pickup so I don’t destroy something inside. After pulling over in a trail side park, I got down on my knees and grabbed the belt drive; it was loose. I know they don’t stretch, so I eyeballed the rear drops to see if they slide forward somehow. No issues there. Then I looked at the belt-ring and noticed only three of the five bolts were there and those three were really loose. The whole belt-ring was flopping around and two of the five bolts had worked loose and were completely gone. Problem identified and not serious!

Whipped out my trusty Crankbrother’s multi-tool and tightened the three remaining belt-ring bolts up snug, then hit the trail on only Level 3 of 9 in 2^nd gear to test things out. Everything was back to normal, so I rode slowly to Warner and exited the trail to swing by Performance Bicycle on Warner and Magnolia to hopefully grab a couple used ones from their parts bin to get me home. No such luck, but they had a set of five black steel ones for $9.99, so I was good.

55.5 miles later I was home with an incredible 48.5V still in the battery.

Oddly enough, I did put blue Loc-tite on those 7000 series alloy belt-ring bolts and thought I slightly over-torqued them for good measure, but this is my first custom build and you live and learn I guess; just like the crank arm bolts coming loose on my first non-powered ride…

Oh yeah, I did get to check the mileage on the display against the trail mile markers and it was a match, so I guess speeds displayed are probably good too.