New DIY Ebike (52V, RH212 Std Wind)
Althoughy my BBSHD and GMAC builds suit me fine for my current needs, I have wanted to try a 9C RH212 Direct Drive Setup for awhile.
From analysis I have done usng the tools available at grin, it should be similar in performance to my 10t GMAC geared hub drive.
I used a surly bridge club frame for this build as I had it lying around (it has also hosted my GMAC and BBSHD). Basically its
standard style vertical dropouts work easiest with the 9C RH212 std wind motor as compared to the Surly Ogre/Troll style horizontal style.
Its not the horizontal dropouts as much as the adapters that would need to be fabricated.
RH212 motor - its a beast
https://ebikes.ca/shop/electric-bicycle-parts/motors/rh212-std.html
I also ordered statorade (10ml) and their V4 torquearm
Anyone considering this motor should also buy some spacing washers available thru grin at the same time. There is a washer that needs to fit over the axle
but inside the cassette and the supplied one with my motor was not thick enough to keep the cassette from rubbing against the frame when
the motor was mounted.
So the cost of a few washers + shipping was $30, uggghhhh, Wont arrive till next week.
As it turns out, you can use the washer available here, although the torque arm is a POS imho
https://www.amazon.com/dp/B07C7J1ZD7?psc=1&ref=ppx_yo2ov_dt_b_product_details
RH212 BridgeClub(BC) Build
I wont go into all the details (unless requested) but I had to settle on a PAS only system vs torque sensing BB (which I also have) due to chainstay clearance issues for now.
See attachment for a pic of the completed build
Ride comparison between my current Surly Ogre GMAC build and the new Surly BC RH212 build
Surly Ogre (52V, 17.5ah, GMAC 10t, 29x2.6F, 29x2.35R Johnny Watts Tires, Phaserunner, CA3)
Surly BC (52V, 17.5ah, RH212, 27.5x2.6 Johnny Watts Tires, Phaserunner, CA3)
Note that I used to run the GMAC on the BC frame with 27.5 tires. From my testing, it seemed about 1-2wh per mile less efficient that a similar 29 inch bike which is why I ride the Ogres now.
All Phaserunner and CA settings as similar as possible, both run in PAS mode (no torque sensor) for this test to have a similar feel although I usually run the GMAC in torque sensor mode.
This ride can be broken down into 3 sections.
Section 1: A 6.5 mile winding gravel path following a creek downstream.
Pretty much flat but lots of turns.
All downwind but shielded from the wind for the most parts.
Need to keep speed reasonable due to gravel/loose corners and other trail users.
Section 2: A 7 mile more open gravel winding path starting flat and getting into a bit of a headwind. Go as fast as you want while still making the gravel corners
A few good shortish climbs 6-8%, many rolling 4-6% hills and then a good 8% downhill section.
Section 3: A wide high speed bicyle commuting lane (seperate from traffic) with 4-6% rolling hills, fighting a headwind the whole way
Total miles: 18.62 miles, 17.4 average speed, 728ft elevation gain
Wind conditons today were winds at 20mph, gusting to 30mph (really an issue in sections 2&3). Temps were mid 50s(F)
Rode with a neighbor (very fast ebike rider, ex motox, 70# lighter than me), and we switched bike(ogre and BC) every few miles.
RH212 Impression
Can we say quiet! First thing I notice when getting on this bike is the tire noise although both bikes were running the same tires. Needs about 200-300w more PAS assist to have a similar feel.
That being said, the power delivery was way smoother due to the lower torque and more powerful at the top end. Throttle is more about adding top speed than anything significant down low. Temps stay LOW no matter the situation. During the 8% downhill in section 2, I had the throttle pegged at 1500W and could only reach 23mph due to the headwind. Due to the lower torque, the motor just feels less responsive although still powerful. This setup is more about top end power although doable for this ride. If I was wanting a high speed commuter, this would be the ticket. Max Temps today were around 38C during section 3 running about 1000w and 26mph. I definately notice the additional 8# or so weight. The bike is less responsive but more planted.
While not part of this ride, I did try a 1500w max power run on section 3 yesterday fighting a 15mph headwind, all above 28mph and max motor temps was 45C.
GMAC Impressions
The bike just feels more lively, the higher torque from the motor just feels more responsive for everyday riding on this trail. The lighter weight contributes to this as well. Max motor temps
were 95C in section 3 at about 1000w and 24mph.
Overall efficiency
15.5 wh/mile for RH212 for section 1, half of section 2, 15.6wh for the GMAC.
25.6 for the RH212 for the whole ride vs 25.9 for the GMAC, we both pushed the RH212 harder than the GMAC
Note that the goal of this ride was not efficiency but to push the bikes as hard as possible back to back on the same ride/conditions