Best Pedal Assist Setup

[majornelson]

Long time member here... I'm trying to re-solve my PAS options. What I'm looking for is the best peddle-assistance solution for a road bike.

My goal has been to create a peddle-assist road bike using a Q100CST (cassette version) that would give me a boast while, at the same time, pedaling as I am a traditional road-biker. Just looking for a little extra as I go down the road. I have built a number of electric bikes that I love but this one is different.

I'm stuck. I'm trying to build a great road bike with peddle assist, modest battery and weight, with decent range and slightly higher speeds than I would otherwise have with traditional road bikes.

I have a 7 ah battery and a Q100CST wheel (700C) that I want to add it to a traditional road bike using PAS. I have several donor road bikes (all steel frame) that range from a 1983 Schwinn le tour luxe to a 20013 Rivbike Homer. I tried initially to use the Rivbike but I'm having trouble getting the PAS sensor to fit to the bottom bracket. Basically, I need a 4 mm gap to fit the PAS sensor magnetic wheel. Most of the new and old frames don't have that level of clearance.

I have a couple of bikes that I built that are throttle mode but for this one I really want peddle assist only. My challenge is that I can't fit the traditional cadence based sensors from greenbikekit sine wave controller in my bottom bracket/crankset. The space is too narrow. For the Rivbike, I replaced the BB (going from 107mm to 113.5mm) but the chainline was off. The chain kept jumping to lower gears if I back-pedaled it (which my LBS suggested as a test). Not good...

I've looked at upgrading to a Thun sensor and CA3 or sticking with my greenbikekit.com sine wave controller and display. I'm stuck...

Any suggestions or ideas appreciate!

Lee

 

[kneedeep]

I have seen a few with the PAS sensor on the crank side without the sprocket. There are also the single pickup sensor you could mount to down tube above bottom bracket and put a few strong magnets on your spoke for chain sprocket to set off the sensor. Same idea as a universal automotive cam sensor.

 

[motomech]

I'm confused, I thought we had worked out your PAS issues in the second half of this thread;
https://endless-sphere.com/forums/viewtopic.php?f=3&t=84433&p=1245512&hilit=pas+torque+imitation#p1245512

The fitment issue of the PAS disc on any crank is easily resloved by removing the inner chain ring and epoxying the disc in place of it. I take it a step further and use the 2 piece "clip-together" PAS from Grin which doesn't even require crank arm removal.

I really question if going w/the pricey Thun sensor and CA3 set-up is a worthwhile investment on a low-powered system.
I'm happy w/ my simple 3-speed speed limited PAS because I engage it on long straights, adjust my speed to IT and that is enough pedaling to give me the work-out that I want.
Now it clear that you want more out of your PAS than I need and although I never got my sine wave/SLCD-3 system working to perfection, Dave said that when it is properly set-up, it is smooth w/ no hesitation.

by d8veh » Wed Mar 19, 2014 7:16 am

You get constant power from the "Torque Simulation" controllers from BMSBattery (S-series). They can be switched from speed control to current control in the LCD settings. In Torque Simulation mode (current control), the PAS levels are power levels, so you get a fixed amount of power regardless of speed. i think that it's not exactly fixed. There's other parameters to make it more practical.

When you have a normal controller with speed control or the above set to speed control, the controller will attempt to maintain a constant speed regardless of how hard you pedal. The speed depends on the PAS level selected or the throttle position, so if you were pedalling with a constant 100w, when you came to a hill, you'd slow down slightly, and the controller will automatically increase the power in an attempt to get back to the target speed. Likewise, as you go above the target speed, the power will be decreased. Nearly all controllers work like this, which seems to be what you're looking for, so you don't need any fancy torque sensors and software or any other complications.

Perhaps you are still having a battery Voltage/controller rating issue?
As far as "no throttle" and needing the "best" PAS response because of that, I'm not sure that any PAS will cover those rare, but awkward moments when one can't get a foot on the pedals. Is it that big a deal to have a thumb throttle there, even of you rarely use it?

 

[majornelson]

I'm confused, I thought we had worked out your PAS issues in the second half of this thread;

motomech,

Yes, that was the start of my build. I'm still at it! :?

I did purchase the Q100CST and the small lunar battery. I had everything setup except the PAS. (I added a temporary throttle and the setup works fine.) When I went to add the PAS sensor and ring, that's when everything started to get complicated. My challenge is that there is no room on the crank side of the bottom bracket and on the left side, there is no cup (?) to hold the sensor in place. It is a Tange BB. I switched the BB out for a Shimano but then ran into chainline issues.

I like the idea of epoxing the disc in place. I had considered it but I have a three speed crank which left 1 -2 mm of room between it and the bottom bracket. But I may be able to widen the opening in the disc. I also have on order in for the 2 piece clip type. We'll see.

In regards to the throttle, I have drop bars so a traditional throttle would be awkward.

Thanks for the ideas and I agree regarding the Thun/CA setup. It's expensive and much more complex (at least for me) to setup.

kneedeep- that's potentially a solution (I need a different type of sensor to make it work- one that clamps on vs. BB ring. And I'd have to be confident that the brake cutoffs worked flawlessly.

At this point, I'll wait for the new greenbikekit clip on sensor and see if I can expoxy it to my chainring.

Lee

 

[motomech]

I like the idea of epoxing the disc in place. I had considered it but I have a three speed crank which left 1 -2 mm of room between it and the bottom bracket. But I may be able to widen the opening in the disc. I also have on order in for the 2 piece clip type.

Don't bother trying to make clearance, just remove the smallest chain ring and epoxy the disc to the back of the middle chain ring.
The sensor-W/ your controller, you should have received a sensor attached to a liteweight steel loop. remove the sensor and reverse it. Then, using a mallet, shape the loop to the contour of the bottom bracket and bend the arm portion 90 degrees so the sensor ends up close to the disc. W/ the bike upside down, hold the sensor bracket in place and test turning the crank by hand. When you have the right position and the PAS works, epoxy it in place and you are done.
It's easier to do than to explain.

 

[majornelson]

Thanks! That's a great idea and will work well for me.

 

[docw009]

I put the PAS disk on the side opposite the sprockets on two of my installs. Consider that, if you see there's enough gap. I've never mounted the sensor using the round ring. I don't trust glue on a bike. I make a bracket and fasten the sensor to a frame tube. Some sensors are critical in how they are positioned. Others are not. Test it before you lock it all down.

I've never ridden a bike with a torque sensor. Some of the guys with the store bought bikes do rant and rave about the experience. I agree that three level PAS can be a little brute force in the lowest level, but five level seems to feel just like a bike to me. Having a throttle, and knowing how to use it with the pedals/gears is fine with me.

 

[motomech]

Glue? In your century that was made from horses right?
I'm talking about a 2 part epoxy, JB Weld in this case. Stronger than the bike frame.

 

[docw009]

JBweld has been good to me, but I'll take a bolt/bracket. This is my fat bike before I added a derailleur and 3 speed chain ring. A front derailleur on a fatbike with two motors is superfluous, but I needed a bigger gear up front.

 

[majornelson]

The PAS sensor on your fat bike is the same one that I have for my road bike. I've confirmed that it works by manually moving the magnets over the sensor.

I tried the non-drive side for the sensor but it's very, very tight. If I can fit the sensor onto the drive side by removing the third ring, I think that I can rig up the sensor one way or the other (or glue!).

Lee

 

[chas58]

The PAS sensor on your fat bike is the same one that I have for my road bike. I've confirmed that it works by manually moving the magnets over the sensor.

I tried the non-drive side for the sensor but it's very, very tight. If I can fit the sensor onto the drive side by removing the third ring, I think that I can rig up the sensor one way or the other (or glue!).

Lee

How did it work out for ya? I had the same problem - just no room between the crankarm and the BB.

You should check out my builds (in my signature). My road bike sounds a lot like what you are doing.

For my road bike, my primary objective is 5mph top speed. I don't use the motor much at all below 15mph. So in that case, a push button throttle on the drops worked out quite well...

 

[majornelson]

chas58,

Thanks for the follow-up! (BTW, I loved the picture of you and your bike in the snow in your build thread!).

I really like the results so far but it has been cold and rainy here (mostly just the weekends ) so I haven't been able to test as much as I'd like.

I ran into trouble on my initial outing where after about 20 minutes the motor would cut out. My display would stay on but just no power. If I turned the unit off and then back on, the motor turned back on but then shut off once I reached "cruising speed". I could turn it off and back on with the same results each time- reaching 18 mph or so (depending on my assist level) the motor could cut out. I had spliced a few cables and my controller was in the rear bag with the 52v Luma battery but the controller didn't feel hot to the touch. A little warm but hardly... and the outside temps were in the upper 40's. I really don't know what was going on but my guess is either a weak splice or the controller was hyper sensitive to heat or is defective.

I re-spliced the battery wires and re-seated all of the standard connects. I rode this weekend for about 50 minutes (it was around 38 degrees out) and didn't have any problems. I need to test again once the temps warm up (not this weekend- forecast in the 30's).

Just a really odd problem.

I used the advice here in the forum and removed my third (small) crank ring and was able to put the pedal assist magnet rotator in it's place. I then used the standard pedal assist sensor mounted in the bottom bracket but added an extra spacer (another sensor holder without the sensor) which gave me enough clearance so it didn't hit the bolts holding the rotator in place.

I wish I had used the higher 320 rpm motor vs. the 201 that I had laced into my wheel. Just like you, I'm looking for a little more top-end as I peddle and don't need (not that you get much) lower end torque. I also like your button method but I'm using drops, so for me it get's a little more complicated as I do move my hand positions up and down the bars. Plus I wasn't quite certain how to make the button (but I'm sure it's documented somewhere in the forums!).

Anyway, great project and I really appreciate your (and everyone else's) help in muddling through it.

After doing all of this I surprised that there aren't more controllers that fit neatly onto a bike. Why is everything square and ugly?? . Also, I don't need the display, I could just use a bluetooth app for setup or communication. If I didn't use the LCD controller I'm not certain how I could change the assist levels, which I move from 2 to 5 depending on terrain and sometimes traffic, without a bluetooth app.

I saw one bike (a Budnitz e-bike) that had an all in one rear hub (motor, battery, etc.) that was controllable via phone. Same on a bunch of pre-built bikes by other manufacturers most notably Faraday (and the phone could easily be mounted to the handlebars through any standard mount). I love the stealth/clean look of the Budnitz and Faraday but both cost a bit and the Budnitz is a single speed. On the Budnitz, the battery is small and the motor (I think) is 24 volts. Most likely too under-powered for guys on Endless-Sphere or even my "need a boost" use. But both are great looking bikes.

For my bike, one thing I couldn't fix is that the display is setup for smaller diameter handlebars and I had to force it on (with longer screws but that only helped a little).

I've attached a few pictures which show the bike and the pedal assist setup. I wanted to clean the bike before posting but that didn't happen.

Lee


View attachment 1

 

[majornelson]

P.S. I don't know why the third photo doesn't display inline. But they all can be clicked on for more details.

 

[majornelson]

Also, the battery and controller are in the rear bag, sold by rivbikes.com. I had the bag modified by my local shoe repair shop to add a front hole with leather reinforcement for the standard ebike wires. The bike is a rivbike H. Homer Hilsen circa 2010. Classic old school steel, nice lugs with 38 mm tires. Great for country roads, gravel paths, fire trails and standard roads. It weighs a total of 31 lbs, battery, motor and everything else included. The Q100 is the great equalizer for my carbon fiber bike friends.

 

[chas58]

P.S. I don't know why the third photo doesn't display inline. But they all can be clicked on for more details.

Probably too big. If it is less than 800 pixels wide, it should go inline.

 

[chas58]

View attachment 1

Lee, I LOVE what you have done with your bike!!!

I bought a mint 1994 steel Specialized Allez to do the same thing with (including your handle bar tape, tan brooks saddle, and bike bag. I thought the down tube shifters would work well with a motor too.

But, I love riding the bike so much I just can’t put a motor on it. I ride it more than my ebike. Also, I can’t put 32mm tires on that bike, so that is a drawback (although the brooks and thudbuster help a lot).

Beautiful build you have there!

 

[majornelson]

Chas58,

Thanks! I know what you mean regarding converting a bike. I really deliberated over converting my Homer but in the end decided that it wasn't that much work or cost if I wanted to change it back to a traditional bike in the future. Hard decisions but I didn't want to shell out the cash to update one of my stable of circa 1980's steel frame bikes in my shed. I also have a mid-2000's trek carbon fiber bike but I don't trust the frame for this setup. So that's my go to if I want a traditional road bike. Its not as comfortable as the Homer but its fun to ride.

Funny thing for me was that it was hard to get used to the larger tires after riding 23mm for so long. Not certain that I'm completely there yet in terms of wheel style but (no jinx here), I haven't had a flat on the bigger tires ever (fingers crossed again). And it handles rocks and gravel really well though not quite as quick on a regular road.

I'll have to check out the Specialized...

Lee