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Possible Soma B-Side Belt Drive or Aluminum Polished Cruiser Electric Option Build

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Possible Soma B-Side Belt Drive or Aluminum Polished Cruiser Electric Option Build

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Old 07-13-16, 08:55 AM
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NoPhart
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Possible Soma B-Side Belt Drive or Aluminum Polished Cruiser Electric Option Build

Now that I have returned to riding for exercise and an interesting hobby; my engineering, early adopter and doer/builder/execution mind wants to make a custom fun do-it-all bike using some of the parts I have accumulated over the last six months experimenting with an eMTB. I want this build to have the option of running a 3spd belt drive or 21-27 gear 7/8/9spd cassette chain drive, plus have the option of using a BaFang mid-drive, standard manual bicycle crank and/or front wheel hub electric motor to play with.

The current parts I have are: RockShock TK 30 Gold Air Solo fork (27.5, 100mm, QR9/100), two new 27.5 x 2.25 Schwalbe Smart Sam Plus tires, Q2 riser stem (black) ,Fouriers Trailhead 58* backswept bars (black w/grey graphics), SQlab 311 17* backswept bars (black w/orange graphics), Aest titanium spindle pedals (blue w/red pins), Selle Royal Respiro saddle (black w/clip-on bag), Zoom alloy seat post (black), 42T Lekkie Bling Ring (blue) and Sunrace 7spd 11-34 cassette.

In addition, I sold my Cane Creek Thudbuster (wrong size shaft) to purchase a pair of Halo Vapour rims (27.5 x 26mm 32H blue w/white graphics) and a Sturmey-Archer 3spd IGH 8-9spd cassette disc brake version CS-RK3 rear hub (1090g, 135mm, 32H). This rear hub will give me all options I’m looking for. It can run an 8-9spd cassette (or my current 7spd with a $3 adaptor) making it a 21-27spd or a single chain/Gates Belt Drive cog with adapter kit making it a 3spd IGH. A big advantage of the cassette 3spd IGH (above and beyond the 21-27spd chain option) over a standard 3spd IGH, is that the single speed kits give you a huge area to properly position the rear cog alignment for a BaFang or crank with gear or belt drive cog.

As you can see from my parts list, this custom build will end up with some pretty interesting color bling factor. I’m thinking of having the wheels laced up with polished stainless steel spokes with red anodized eyelets to match the pedals. Some blue cabling and blue, red or polished levers might be interesting as well.

I haven’t committed to a frame yet, but the Soma B-Side’s geometry looks great and my forks are a direct fit to its’ geo and head tube. Plus, in the V2 form I’ll have the option to runa belt drive in the future. The other frame possibility I’m tossing around is a polished aluminum beach cruiser bike similar to the Felt Maxswell (only larger if one exist?) that has a 1-1/8” diameter fork head tube and rear facing slide in 135mm axle spacing that can fit a 27.5 x 2.25 diameter tire.

I’m keeping my human vs. electric assist options open to keep this bike spend extremely versitile going forward. Much will depend on if my current eMTB sells or not. If not, the BaFang can be repurposed to this custom build. In the meantime I can install the new rear wheel with my existing Sunrace 7spd 11-34 cassette (which has a 20 and 22 sprocket within it) on my current eMTB to fine tune 3spd IGH gearing. Testing so far indicates a 46T x 22T/42T x20T (or 42T x 22T for better hill climbing) is near the all around sweet spot for the 177% range of the Sturmey-Archer IGH. This allows for 2nd gear starts, then shifting to 3rd for normal riding and reserves 1st for climbing hills. I’m told the 2nd gear on the Sturmey-Archer and Nexus/Alfine 3spd IGH hubs is a very strong 1:1 setup that can support high powered electric assist starts as well.

That’s my plan for now. What do you think? All thoughts of other frame options, gearing and the build in general are greatly appreciated.

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Old 07-30-16, 06:29 AM
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Wheels are scheduled to arrive tomorrow, then will have to get them laced up. I went with a SRAM X9 100mm QR front disc brake hub and also an X9 3 speed ball bearing derailleur shifter. Planning on black DT Swiss spokes with chrome brass nipples now (pretty basic), but have a couple questions for those of you that know a little about wheel building.

The rear hub will take 13g or 14g spokes. What guage should I go with? Also is there a specific DT Swiss spoke that would be best?
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Old 07-31-16, 04:02 PM
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Christmas in July!



All the goodies for the wheel set build are here. Found the DT Swiss Alpine III triple-butted spokes (14/15/13) in Sheldon Brown's Wheelbuilding post, then went to the DT Swiss site to reserach them. Sounds like a good choice for this build and it even mentions they are a good choice for heavier bikepacking bikes and E-bikes. They are 13g at the hub, narrow to 15g in the center and go to standard 14g at the wheel nipple.

Hopefully off to the wheel lacers next week...

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Old 08-09-16, 09:44 AM
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Because this ride will be designed for pedal only and/or electric assist and belt drive (which can’t cheaply be changed like a chain bike), I will be limiting 3rd gearing to about 15mph at 80rpm cadence. That’s plenty fast for the flats off-road, beach cruising and general bike trails. I’m no powerhouse single speeder, so I want a low enough 1st gear to be able to climb, yet a high enough high gear to hit about 15mph when doing pedal only.

Front Gates belt drive sprockets seem to start at 46T and I believe that size bolted to an adaptor will clear a BaFang motor housing (the well known Lekkie Bling-Ring is 42T), so that is what I will use if it clears. Running 27.5/650B X 2.25 tires with 46 X 28 gearing yields 10.7mph in the 1:1 2nd gear, and yields about 8.03mph in 1st and 14.23mph in 3rd. This should work well for pedal only (01.23/1.64/2.19). My local beach boardwalks are limited to 10mph, although they are frequently ridden much faster in areas where people are not present, so limiting to 15mph will keep me under control. Hmmm… I wonder why I happen to be zeroing in on Europe’s maximum assist speed. Maybe there’s some logic in their seemingly slow speed madness after all…

Another reason I have zeroed in on this gearing (besides the fit for my pedal only abilities and intended use) is that my 350W/37V BaFang mid-drive eMTB had a low gear of 34T and a Lekkie 42T up front (8.1mph/0.809), which will match 1st gear with this 3spd IGH. That ratio allowed me to climb just about any steep hill on my local off-road trails with leg assist. I’d still get a workout on those mile long steep climbs, but was able to complete them without having a heart attack. I know a 0.810 ratio is very low for most single speeders, but hopefully I can improve enough to make that work when needed without electric assist for the majority of my planned usage over time. I know it is low enough for my ability general use, including short freeway over/under passes on the street and bike trails. Remember, this ride will be general recreational use; that includes beach cruiser duty.

After much consideration on frame selection and size, I think a large will be best even though I’m 6’2” with a 34” pants inseam. There are a couple reasons I’m going to size down from my typical XL on this build. First, a more upright sitting position is desired with sweep-back handlebars for the type of riding to be done. If reach proves tight for me (it shouldn’t be), I can install a setback seat post and this will move the pedals a little further in front of the seat as well; good for cruising. Second, this ride will also serve double duty as a loner for others that want to join me on a ride, while I ride my carbon CS Hightower. The shorter seat post length on a large frame (18.5” on the Soma B-Side) allows for a very low sitting position if needed for other riders. Geometry won’t have to be perfect for them, because those without their own bike probably won’t be highly skilled riders anyway, and the electric assist will make up for any minor inefficiencies in fit if they are smaller than optimal for a large frame.

That’s where this build stands at present. The wheels and hubs are at the LBS getting laced up and surprisingly my prior eMTB is still for sale at far less than it can be built for. I’m hoping I don’t have to repurpose the BaFang off that ride to this one, as it is a great ride as is. I hate to break that sweet ride up, but only time will tell…

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Old 08-18-16, 02:53 PM
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I'm all in now with the Soma B-Side

What a quality well made frame with Belt Drive option.



Wonderful paint.



Cool pumpkin orange, colorful labels and beautiful.



Still waiting on the LBS to measure spoke lengths, order them and lace up the wheels...

Can't wait to get started on putting it all together.
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Old 08-21-16, 09:38 PM
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This is a Tange Prestige Chromoly steel frame that weighs in at 5.5lbs. according to Soma.



I found gearing of 46Tx26T and the 115T Gates Belt Drive stated on the Soma site as well, so I may up my gearing to what appears to be recommended by them for single speeders (1.77 @ 1:1), putting my 3spd at (1.33/1.77/2.35). That yields 8.7/11.6/15.43mph at my stated spec's above; a little faster than originally planned.
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Old 09-15-16, 10:58 AM
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Every bike build needs at least one parts layout photo, so here it is. Not all parts listed are in the photo, as a few are still on their way....



The wheels are all laced up with Alpine III triple-butted spokes for strength to handle my 230lb body plus gear and the hardtail beating they will sometimes get. The Schwalbe Smart Sam Plus E-bike Rated tires worked so well on my last E-ride that I carried them over to this one. For some reason they look larger and wider than the 2.25" that they are; almost 27.5+ like, but they are not. The "Plus" refers to the Green Guard puncture protection built into them. The "E-bike Rating" is for safety reasons used overseas and carries a speed rating up to ~31mph.

This is the parts list so far:

SOMA B-SIDE Frame (Large - 18.5")
Cane Creek ZS44/28.6 Tall, EC44/40, 52/30 Conversion Race
RockShox 30 TK Gold Solo Air Fork
Single 40mm Fork Stem Spacer
Q2 40* Riser Stem 110mm
Fouriers Trailhead 28* Sweep Bars
ESI Chunky Sylicone Grips 32mm
SRAM X9 front hub
Strumey-Archer 3spd IGH 8-9spd Cassette Disc 135mm (CS-RK3)
Halo Vapour Rims 21mm
DT Swiss Stainless Steel Triple-butted Alpine III Spokes Black (14/15/13) Silver Brass Nipples
SRAM Centerline 180/160mm brake rotors and adaptors
Schwalbe Smart Sam Plus Tires with Green Guard (31mph E-bike Rated)
Schwalbe 27.5 x 2.25 Tubes
Circus Monkey 27.5 x 18mm rim tape
Aset Titanium Spindle Alloy Flat Pedals
Cane Creek Thudbuster ST 27.2 x 410mm
Soma 29.8mm Seat Post Clamp
Selle SMP TRK (Serfas in pic was too soft for me)
SRAM X9 front 3 Speed Trigger Shifter

I haven't decided on brakes yet, but I'm seriously considering the SRAM AVID DB3 hydraulic set mainly because their style of handlebar clamp. DB3's are adequit for my general trail needs and certainly fine for flatland cruising. They have a split 2-bolt mount that can accept a motorcycle kill switch on the back half like this one.



I'm hoping to wire up a "Boost Button" using one of these to keep the handlebars clean and neat. I like having a throttle option, but don't mornally use it like a typical throttle. I use it only when I need a "boost" to the pedal assist (PAS) system as a full-on only button to push me a little harder when my human power is dying out on a climb.

Today the T-9 will be sprayed inside the frame tubes for long-term protection. Hopefully assembly will begin this weekend.

Really enjoy building my first custom. I've built motorcycles, three-wheelers, sandrails and a number of cars over the years. Builds of all types with "new" parts are always the best. At my age I'm no longer into cleaning and restoring/refurbishing each piece to complete a build. You hardly even get dirty building with new parts and you get the satisfaction of creating something unique and personal. Wonderful experience!

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Old 09-26-16, 09:46 PM
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Old 09-29-16, 01:02 PM
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A little tease for the popcorn crowd…



Ran into a couple problems while completing the build. First, I ordered a 28.6mm Thomson seat collar, but that was actually the front derailleur size specification. It should have been a 29.8mm. Second, the stem spacer I had here totaled 35mm which is about 3-5mm too short and I don’t want to cut the fork down any further, so I’ll probably order a solid 40mm stem spacer for a nice clean look.

So far I’m really happy with the look and measurements taken. The laid back handle bars and slack head tube angle are sweet. The top tube came in at about 30” stand over height. That will allow a variety of sized people to ride it easily, yet with the 400mm Thudbuster ST and rise stem it will fit my 6’2” body comfortably. This eMTB Trail/Cruiser will be for my personal “kick-around” enjoyment, as well as, a loaner for others to join on rides that might not be fit enough to keep up otherwise or are thinking about getting into biking but don’t have a bike yet.

Leaning strongly towards another BaFang mid-drive with a large capacity battery for added range. The beach is 17+ miles away by car. It would be great to have enough range to cover 20 miles each way and another 10 miles while there, so a 50 mile full power range setup might give me the cushion desired. I will have to consider the ever present range verses weight dilemma E-bikes still have with today’s battery technology.
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Old 09-29-16, 10:30 PM
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Looks good so far!
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Old 09-30-16, 10:37 PM
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Looks nice!
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Old 10-01-16, 06:31 AM
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You are having way too much fun!
I see the thudbuster is back!
I use a doorbell as a boost button on my road bike, as I there isn't anything that fits drop bars.
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Old 10-01-16, 08:55 AM
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Thanks for all encouragement. This is a lot of fun! Can't wait to ride this new build...

Yes, had to get a smaller post Thudbuster to fit this frame. I went with the Short-Travel (S-T) model this time. The Long-Travel (T-L) was very nice, but a little bit too busy in the cockpit area for me.

Found a black Soma brand 29.8mm seat post clamp and a 40mm single spacer for the stem, so they are on their way.

Liking the bright positive happy colors. Considering white/gray with black hoses now for the brakes (the handlebar has gray graphics) instead of my original plan to do multi-color hoses and cables. Probably going to stick with the orange/black/white colors of the frame and blue/white wheels with a few small gray/red accents. Minus well make it obvious it's a custom build.

Also, I'm thinking if I go with the BBS02 750W/48V mid-drive I'll start out without a throttle. With that much power on tap, I might not need any "boost" above the top power setting level. That will eliminate more wires.

Does anyone know of a top tube plastic mount that might be adapted to the BaFang display? I'd prefer it to be down on the top tube just behind the head tube instead of up on the handlebar.

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Old 10-07-16, 06:00 AM
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Found a set of new Shimano XT M8000 hydraulic brakes for a reasonable price, so I picked them up. I've always wanted to try them out. Now I can do a hands on comparison to the Sram Guide R's on my CSH.

After much thought I've made the decision not to run a throttle at all. My last eMTB was a 350W(~680W peak)/36V and the throttle was great when used as a boost button on climbing steep hills when still pedaling. With a 750W/48V system I will already have access to more power than the peak power of my prior system, so the assist level control should provide all the variance I need (at least on paper it appears that way).

Still waiting on the seatpost clamp... Picture of the finished product sans power system soon.
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Old 10-08-16, 11:18 AM
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It痴 coming together nicely with just a few hiccups in parts ordering so far. The Shimano XT M8000 hydraulic brakes came with hoses longer than stated, but they can be trimmed down after I confirm the handle bar height and position. The bike is just about complete except for the power system, sprockets and chain/belt.



Still need a cable housing for the Sram X9 3spd shifter, but haven稚 decided if I want to go blue like the grips or black yet. If I have to trim down and re-bleed the brakes, I can go blue hoses there too if desired to make it pop a little.

This project may sit for awhile during the coming holiday months as life takes priority. Maybe Black Friday will yield some kind of super deal on a power system, who knows.

Now it痴 off to the Orange County International Auto Show to take a close look at the 2018 Hyundai Santa Cruz in my avatar (ADDED: Hard to believe that Hyundai didn't have the Santa Cruz prototype that their CEO says WILL BE IN PRODUCTION in 2017 as a 2018 model at the show AND Mercedes Benz wasn't included in the new Work Truck section with their Metris and Sprinter; so the two vehicles I went to see weren't even there. )

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Old 10-08-16, 04:54 PM
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As I research my options for the power system, I came across this article about the BBS02 and the new BBS02B that apparently just showed up unannounced.

Thought I'd post a link here so others reading this build will be aware of the change.
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Old 10-17-16, 10:07 PM
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Here's another mid-drive that actually has a torque sensor, the TDSZ2. The guys over at ES have started testing it in the real world and tearing it apart to look inside too. It appears to be noisier than the BBS02, but some like the torque sensor power application better. Here's a link for their discussion:

https://endless-sphere.com/forums/vi...p?f=28&t=79788
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Old 10-18-16, 10:47 AM
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Geeze, trying to feed my addiction, or what. I was thinking about getting a torque sensor, but a compact motor and battery and torque sensor all in one package. Now that could be entertaining. Hmmm... I do like smaller lighter 36v batteries, and if the thing will go up to 45km/hr, it could be entertaining!!!
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Old 10-18-16, 12:34 PM
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Awesome! I'm about to convert my Marin Pine Mountain custom build, which sits about like your Soma, only with a rigid steel height-corrected fork instead of a suspension fork. I also use that same Serfas saddle from your parts pics above, which works well for me since I'm pretty upright on my bike. And like you, I'm also considering the BBS02 750W mid-drive motor, with pedal assist, likely no throttle.
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Old 10-19-16, 08:31 AM
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The BBS02 750W-48V mid-drive is a proven winner and quiet! The TDSZ2 peaked my interest because of the torque sensor, but the noise and reliability don't appear to be up to par. The lower ground clearance concerns me too. I found myself worrying about bashing my BBS01 on my last eMTB even time I cleared a curb or large rock, but never hit it in the six months I had it.

I have this project and a carbon 29er full suspension MTB that I'd like to add some kind of E-assist just for climbing. The rest of the time it will be completely off, so it has to pedal like a normal MTB without power. That may prove to be difficult. The only solution I've come up with for that bike is a small geared electric motor like the MY1018 (decades old Currie brushed motor type) mounted mid-frame combined with a free-wheel crank; possibly on the left side. That little motor only weighs about 5lbs. and appears to be able to handle 450W-36V.

The dilemma I find myself in is the best way to experiment with that setup is to first put it on this build, then transfer it over to my primary FS MTB if it works as planned. This is one reason I've hit an impasse.

I'd probably be better off just putting a BBS02 750W-48V on this baby and start riding it, then messing around with a custom crank setup for this that probably won't work on my other ride.

Has anyone close to Bafang heard if they are any closer to making a torque sensor mid-drive motor yet?
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Old 10-25-16, 09:34 AM
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Well, I have decided to move forward with testing a MY1018 450W 36V custom mid-drive setup on this frame prior to moving it to my full suspension MTB. I picked up an all aluminum housing MY1018 / YK31C controller and have an under bar left side thumb throttle that I might try on the right side as a finger pull throttle. This motor should be close to only 4.5lbs.

I hope to combine those two items with a freewheel crank and freewheel sprocket on the motor itself. This should provide the absolute minimum drag possible while pedalling without power, allow back pedalling and allow throttle while coasting (not pedalling).

The motor will be mounted within the frame triangle with brackets from the BB attached to one of the two bottle mounts for torque support. Eventually I will do some calculations for the best light wieght small capacity battery for this hill climb only application.

This kit is very similar to what the end result will look like, but the motor will be an all aluminum one without that heavy flat metal bracket and housing; and not mounted under the frame triangle, but within it.



Here are the motor and controller stated specifications:

MY1018 - 24V 450W GEAR REDUCTION “BRUSH” MOTOR
(Came with rear stay mounting bracket, sprocket, chain, nuts & bolts)

Specs:
- 24 Volt, 25A Rated Load, 2.5A No Load
- 1.43Nm at the output sprocket @440 RPM
- 12 gauge power leads
- Reduction Ratio: 9.78:1
- 9 tooth sprocket for 1/2'' x 1/8'' pitch standard bike chain
- Direct Drive (No Free Spooling)
- Alloy case for good heat dispersion.
- Bicycle style mounting bracket Included. (Suits the 250w and 450w models)
- Suitable for Forward and Reverse Operations
- Weight: 2.2KG / 4.85LB (alloy motor and frame!)


YIYUN TECH - YK31C
(Brush motor controller for electric bicycle & scooter)

Rated voltage: DC 36V
Current limit: 28A
Rated power: 500W
Matching motor: DC brushed motor
Under Voltage Protection: 31.5V

Wire Interface Definitions
Battery: Thick Black (Power Negative) / Thick Red (Power Positive)
Motor: Thick Yellow (Motor Negative) / Thick Blue (Motor Positive)
Ignition Switch: Thin Red (VCC) / Thin Blue
Indicator: Thin Red (Indicator power output) / Thin black (Indicator Negative)
Brake: Thin Yellow (Brake signal) / Thin Black (Negative Power)
Speed governor: Thin Blue (Speed handlebar Signal input) / Thin Black (Negative Power) / Thin Red (5V Positive Power)
Charge Port: Thin Red (charge input power Positive) / Thin Black (Power Negative)
Brake Light: Thin Red (power Positive) / Thin Black (Power negative)

Last edited by NoPhart; 10-25-16 at 10:25 AM. Reason: Add pic
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Old 10-25-16, 09:48 AM
  #22  
NoPhart
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One area I can use some input is what further gearing reduction I need to have the motor turning at its' peak torque and efficiency for a comfortable cadence. Maybe one of the gear calculators that list this motor might be helpful in that regard? My initial thought is to reduce it by another 3:1 or 4:1, but I have no real justification for that ratio other than dividing 80% of the motor 440rpm by 3 or 4 to get 117-88rpm cadence (not sure if that logic is close to correct?).

Please bear with me as this is my first custom electric bike build using individual components.

Here are some possible relavent factors:
230lb. rider
Current bike is 27.5 x 2.25 wheels/tires with 50F x 28R and 3spd IGH (0.75/1.00/1.33)
(Eventually it will be installed on a 29 x 2.3-4 with 30F x 10-42R)

Because this is a mid-drive setup, it makes sense to me that I concentrate on getting the cadence at the crank right and just let the gears do their thing. Is that logic correct?

Last edited by NoPhart; 10-25-16 at 09:57 AM. Reason: typos
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Old 10-27-16, 08:35 AM
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The ebike.ca simulator is what I use.
Motor Simulator - Tools
It is an amazing tool if you are technically inclined.

You can see on that tool, that motors peak at, what, maybe 75% of the no load speed, and then the power needed vs power produced lines usually cross around 80% of the no load speed.

Voltage = speed.
440rpm at 24v = 36/24*440 = 660rpm @ 36v. (50% more volts = 50% more speed).

If it is rated at 440rpm, that would be its no load or maximum speed. It is basically making no power at or above this speed. Top speed on the road would be roughly 80% of this.

As a “roadie” I pedal at 100rpm. Anything over that is kinda crazy fast (unless I’m sprinting at the track).
90-100rpm is generally considered a good cadence, and electric motors like to spin fast. Most of the BBS mid drive failures are because people spin them too slow for too long. So, shoot for something in that range. 88rpm is fine, 117 rpm is going to be hard for your legs to keep up with.

With an ebike motor, you typically don’t need a lot of gears. My bikes are set up as single speed or two speed (although I’m not grinding up long steep hills). You need to turn the power off when (derailer) shifting a mid drive, so fewer gears is probably better.
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Old 10-27-16, 06:42 PM
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Thank you chas58 for posting your hands on knowledge. I'll go try to figure out the calculator this evening...

I've kind of mixed two builds into one here, because I was thinking of testing out the MY1018 on the Soma before moving it over to the my FS MTB, but it turns out I'd have to invest in many parts that aren't compatible, so I'm switching gears once again (pun intended!). I'll have to start another thread for the MY1018 FS MTB hill climb assist only build.

Back to the actual Soma B-Side V.2 Belt Drive build powered by a BBS02 750W 48V mid-drive:

My Gates Center Track Carbon Drive 50T front sprocket arrived and from what I can tell the outer flared lip is about even with a 42T Lekkie Bling Ring, so I think it will clear the BBS02 gear reduction hump without modifcation. The two chainrings are about the exact same size in diameter.



I won't know for sure until I actually test it on a BBS02 and play with the inward spacing off a 130BCD adapter spider. My fingers are crossed that the CS-RK3 cassette in back will allow enough outward spacing for the rear 28T CDX cog to line up. I decided to stick with the Soma single speed recommended 46T X 26T ratio of 1.77:1; 50T X 28T comes in at 1.78:1. That setup calculates out to a 118T Gates Carbon Drive belt at 432.79 chain stay length.
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Old 10-27-16, 10:37 PM
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Well, that motor simulator seems to be for hub motors only. When I click on display the whole motor window goes blank (?).

Gearing for the MY1018 for crank cadence seems to be 12T X 46T for the GNG mid-drive kits using the similar MY1016. I should be okay if I can find a 12T 11mm bore 4mm keyway freewheel (I know they exist, but I can't find one) and a 46-48T chainring at the crank giving 88rpm using 80% of the stated 440rpm. I'd much rather use the supplied fixed 9T that comes with the motor and some kind of special freewheel only on the crank to motor chainring using a 36T for the same 4x additional reduction, but can't come up with an easy solution for adding an outside chainring freewheel only, while keeping the inside chainring fixed to the crank. I'd prefer to keep the Race Face Aeffect SL crankset that's in place now.

If I want to drag the chain to the motor while pedalling without power 90% of the time, all I need is a 12T freewheel for the motor shaft. I can use a dual 64BCD/104BCD cinch spider for the two chinrings on the crank.

Does anyone know where I can buy a 12T freewheel with 11mm bore and 4mm keyway for a MY1018?
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