Motobecane DS Fantom, BMC 600W torque and now Lipo build

[kfong]

Latest breakdown, was in the trails today when the bike started acting funny. I thought it was a bad connection. The throttle kept changing on me. I could not find anything wrong with the connectors so I cut short my ride. On the way back I noticed the speed indicator on the CA going over 100 miles per hour. This was higher than my 99 max setting. I took a clue from that and reset it to 0 mph. That solved the thottle changes. I now have a CA with a bad speed indicator. I will have to take it apart and see what's wrong. The CA has been reliable up till now. Apparently when it went past 99 mph it would cut off the throttle to limit the speed. Hopefully it's an easy fix. The wheel setting is at 2011, the same as it has been when I calibrated it. Everything else on the CA menu checks out. I have to verify the speedometers output next. I might have to do a full system reset as well.

[shock]

It was great meeting up Vince! Ive been thinking about putting knobby dirt tires on mine ever since I rode your setup. One option you could do is run no CA. Voltmeter is enough gauges for me

[kfong]

Hi Joe, you will have to try out the trails I ride. I've been riding so much my right hand actually needs a break from it. It hurts each time I ride now. It's the half twist throttle position and hand fatigue of holding the throttle position. I haven't been able to come up with a better solution. My ideal setup is to use a torque sensor and only pedal input but I have not been able to find a reliable sensor that is affordable. It was also injured during a windsurf session, bike riding just hasn't allowed it much chance to heal.

I can do without the CA by just using my Smart Switch, but I kinda like having the voltage, speed, capacity and other info available when riding in the woods. It allows me to estimate when to turn around or if I can do that one loop once more. It was really useful the day we did the ebike meet. I didn't have any range anxiety since I could see what was left and how fast I was burning up the packs. I just need to tear it down and scope out the signal. Hopefully it's an easy fix.

[kfong]

i took the CA apart. Signal going to the sp pin is clean. It goes from 5 volt to ground when magnet passes through the sensor. Either the processor is bad or the signal conditioning circuit is bad. Since I don't have the schematic I will have to contact Grin and see if they can help.

Just discovered this while searching their site

With Stand Alone CA units shipped prior to June 2007, the capacitor used to filter the signal from the speedometer pickup was not always adequate at eliminating switch bounce from the magnet sensor. This could cause brief periodic speed glitches in the +100 km/hr range. Simply repositioning the magnet would generally cause the problem to go away, but if it continues then capacitor C6 on the back of the circuitboard should be increased from 1nF up to 30-100 nF.

It looks like I have a debounce problem. Although mine is ver. 2.1

Well, that was an easy fix. Apparently the trail riding moved the magnet into a position where the debounce circuit was overloaded. Works fine once I repositioned it. At least I know what to do if it happens again and setting the default speed to 00 to disable any speed restrictions.

Update:
Rode it this morning, bike is running great. Setting the max speed to 00 was wrong. All I got was a 13 mph max speed, back to 99 allowed me to run at 23-24mph again. It really should have a speed disable function.

[kfong]

I did 44 miles today. The last few miles I had to pedal without power, mostly 20-25mph on the streets and what pace felt good in the trails. With the larger capacity I can ride from my house to the trails and still have plenty of capacity to explore. My ass now gets sore from the long rides. This is the first time I have been able to drain the packs from a ride. Found one bank lower than the rest. It didn't take long to balance, but I will keep monitoring that bank after any full discharge. Total capacity put back into the packs was 24.256 amp hrs. Voltage cutoff was at 43 volts.

I actually forgot to reset the CA 44.13mile 22.7ahs so a couple ahs are unaccounted for.

I did do 46miles all pavement but only used up 21 ahrs a couple week ago, was kinda tired to ride out the pack and it was getting dark. Pretty sure I can hit 50 miles if all pavement and peddling while at full thottle most of the time. The bike is setup good for peddling up to 25mph. The more I ride the better my legs get a helping out. I notice this at the end of each riding season but seem to be getting them in shape already.

[shock]

Sounds right in spec for lipo power. I did 23 miles yesterday, of city. Ended @ 44. Waited until now to fire up the charger. Looking forward to some trail rides.

[kfong]

Hey Joe, the trails are in great condition. Wearing gloves to keep my right hand functional so I can ride. I road from my house to the post office at 16 mile then down 16 mile to John R. From there straight north to Bloomer park. Covered all the trails their at least twice then on to paint creek trail to Stoney Creek park, rode the fast trail section by the BMX area. Tried the BMX section but the bike needs to be more like my RC build to work it. Realize I was cutting it close so headed back the same way. Going to have to drive to my favorite single track at highland state one day. It's been a while since I've had a fall, that place usually gets me on the ground. I wish we had more advance trails like out west. I did have to bail recently at dodge park going up a plank, need more practice in that area. Bike came down hard on its side but was fine. There is also a nice drop off, great for getting some air. I've had a few close calls on it. Hopefully they keep adding new stuff.

Another 30 miles today 6/9/2012, all trails. Went to Pontiac state park. The loop is a little over 10 miles. Was in good form the first time around, second time through I had a hard fall. Was thinking I could use full body armor after getting up and checking my right elbow. Ground was hard, with mostly buried rocks. Was getting sloppy with fatigue, had one more hard fall on the third loop around. Started slowing down after that and just took it somewhat easy. Bike is holding up with all the trail abuse. It's no DH frame, but neither is it heavy like one. I did bottom it hard during one drop off, which had me concerned about the rear shock. I've been very happy so far with the performance of this bike. Very nimble in the trails, which is all single track.

[kfong]

It's been a while since I posted an update. Was pretty much riding it till I started working full time again. Not much riding these days due to weather as well. About 3 weeks ago I actually had a break down. The ratcheting sound after pushing the bike pretty hard up a hill became quite loud and soon after just a hum without any power to the wheels. I suspected the clutch had finally given up. About a week later, I finally had time to take it apart. I found that keyway had sheared completely in half. It had damaged the surface as well, but this wasn’t much of a problem to smooth out. It must of taken a lot of torque to do that. I replaced the keyway with one I milled out. The clutch was also replaced since it had much more rolling resistance than the new clutch and I was not about to do another rebuild. The good news is the gears look great after 3 years of hard riding and jumping. Here is a picture of it after all the grease had been cleaned off. It looks like it was just bought. The clutch replaced was another V3. It sounds like the newer V4 clutch has even lower rolling resistance. I will have to go that route next time.

gears still looking new.jpg (74.84 KiB) Viewed 1219 times

split keyway.jpg (73.99 KiB) Viewed 1219 times

Damage to surface from split keyway.jpg (71.25 KiB) Viewed 1219 times

This weekend was the first time I was able to take it out riding again. Sure felt good to hit the trails. It’s been warm for this time of year as well. The bike performed great as usual and left me with smiles. Looking forward to spring. I should have replaced the rear tire while I had it apart. I need to find a good tire that can last a bit longer than the soft trail compound of the velociraptors. The center is pretty much bald with the sides still looking good, and this is pretty much after one season. Any ebike trail tire recommendations out there? You can see the wear is actually into the liner now.

tire wear.jpg (55.75 KiB) Viewed 1215 times

I still need to get the covers completed so it fully encloses the Lipos. It should be done this winter. I had a bad crash worth mentioning while riding the trails at night about a month ago, clipped a tree and went down hard. Stopped night riding after that. Need to have a lot more lighting if I were to do it again. Only had one magic shine and a low power helmet light.

[oatnet]

Glad you are OK after your fall. Do you think that might have anything to do with the sheared key? I have not seen a report of that on BMC/MAC before. Thanks for the GREAT data point on gear wear in the BMCs - guess we don't need noisy steel gears after all!

-JD

[kfong]

Crash was all my fault, just didn't see the tree with the low light. With work, I had limited trail riding time. Thought riding at night with lights would work out, but really needed more lighting to be safe. Until I get that worked out, no more night rides. Weather now is too cold, time to work on bike builds.

Yeah, I expected to see more wear after cleaning off the grease. The keyway was relatively easy to replace. Still very happy with this motor as my choice for trail riding. Not much I would change on this setup.

[oatnet]

Crash was all my fault, just didn't see the tree with the low light.

Sorry, I meant do you think your fall is what might have damaged the key, and started the shearing...

-JD

[kfong]

The shearing probably happened over time. I've had so many falls on the bike, that pinpointing it on one fall would not be likely. Hard acceleration and hill climbs probably did it in. The keyway is soft as well, the one I replaced it with I decided to harden with a butane torch. Not sure how well this works, waited till it glowed to straw color, then dropped in water. I figured since the gears looked good, I might as well let them take on the stress.

[teklektik]

I replaced the keyway with one I milled out.

BMC motors use a 5mm x 5mm x 11mm key. You can buy a 25mm (1") piece of 5x5mm keystock from many power equipment service/repair stores for a buck or two - it's a fairly common item. File a rounded end, trim to length, then file other rounded end. Also, FWIW - the key is the bit of metal that fits into the slot or keyway.

[kfong]

Thanks teklektik, good to know. In my case it was just easier to have the CNC just cut a few out. Had to guess on the dimensions. Will use your measurement next time.

[shock]

Hi Vince, glad to see the motobecane is still up an running Still admire your battery and wiring setup, very nice.

I am in the course of completely rebuilding my motobecane right now, upgraded phase wires and air cooled the hub, going to a 12FET lyen, and 18s. I found some 6cell 5k mah blue lipos dirt cheap again on black friday hobbypartz sale. I got 6 of them. I am planning on regen so I want to beef up the torque arms, and yours look the part. Aquired some DocBass steel torque arms but really my last resort as I don't want to glue them to this particular frame. Maybe we could meet up and I could pick your brain a bit about a good solution. I would have no problem paying you for your time and materials if you have the time and resources to CNC me some good bolt on torque arms. Wondering if you still have the CNC file for your torque arms, as I believe the swing arm is the exact same as your bike.

-Joe

[kfong]

Hi Joe,

Working full time again, and have so little time these days for ebikes. Once riding season is upon us, I will have zero time. The parts were made of stainless steel, it was a bitch to cut on the micro mill. I will not do it again unless it's for my own stuff, since loosing some cutting bits is guaranteed. It also takes forever to cut since the passes have to be very light. You are better off getting it cut on a waterjet from one of the local shops and getting it customized to your hub motor axel since mine was for the BMC V2T.