BBS02B Crank Breaks Loose From Engagment And Spins Free?

[Rider]

ADDED 7/15/2017: AT THIS POINT I AM 99% SURE THE ISSUE IS THE REAR HUB SLIPPING AND NOT THE BBS02-B

My BBS02B 750W/48V running on a 48V P-S GA battery pack now has over 1,300 miles on it. I ran it right out of the box completely unmodified and haven't done any maintenance to date. Maybe it's time...

An odd thing happens now and then usually when under heavy pedaling in level 8-9 of 9. The crank breaks loose from engagement and spins free (like I pulled a clutch lever in). After a brief pause, I start pedaling and all is back to normal. I don't think it is the rear hub. It doesn't slip, then catch. The crank completely disengages and spins free, like something inside the BBS02B triggered the release. After I coast a bit, then start pedaling all is fine.

This is very infrequent, but it is happening enough now that I want to understand what it is and what is causing it. Any thoughts?

[Rider]

It did it again on this mornings 40+ mile ride. This time I wasn't in a high power level (IIRC 4-5 of 9). The initial somewhat of a "clunk" release makes me wonder if it is the hub and not the BBS02B...

Anyone have a thought on what this might be? I guess it could be the rear Sturmey-Archer 3spd IGH hub slipping? This is my first IGH and I've never had any issues before.

I only found one other trouble shooting thread here that sounds close:

https://electricbike.com/forum/forum...utch-freewheel

Does the heat sensor shut-off feel like the crank slips into free wheel when it is triggered? I wouldn't think it would start working again right away if it was the heat shut-off sensor.

All I really got out of that thread was re-greasing everything seemed to fix it. That seems odd...

I'm about to swap this BBS02B from my Soma B-Side 3spd IGH over to my Electra Cruiser 5spd IGH build in a few weeks. At that time I plan to do a maintenance inspection and re-greasing. Running it with a different rear hub will eliminate the hub as the cause if it doesn't go away, but I'd sure like some experienced opinions on what this type of behavior might be. Thanks.

[Gr8fun]

This is close to what happened to me.
I changed clutch, problem persisted. Looked at secondary gear , pinion, all seemed ok. Took apart primary. Nylon gear seemed okay. Regreased and everything is ok for two weeks. Now it is reoccuring. I have another nylon gear (the bearing s one way or freewheel also) should be here by end of week. Bbso2A. Had to order from china. The b version is available in usa. I do not think possible to tell without inspection?

[calfee20]

Does it do it in any of your three speeds or only in high. Second is direct or the hub is locked up. What you are describing is exactly what my 5 spd was doing in 4th and sometimes 5th.

[Rider]

Gr8fun - Are you running an IGH? If so, what kind?

calfee20 - I didn't realize your SA 5spd issues were similar to this. I'm having trouble reconciling in my head how the crank can go into free wheel if the rear hub breaks free of its' lock-in position. Wouldn't it just skip to the next lock-in position and NOT allow the cranks to free wheel? I haven't spent any time reviewing how the internals of the SA 3spd work. Maybe I should ask the guy over on electricbike-blog that has done all the IGH testing until they break what this symptom is.

It only happens in 3rd gear, but I am always in 3rd gear after the first 50 feet. My 2nd which I use as 1st is geared to a low 1.785, so it's only used to get started. 33% higher is a final gear ratio in 3rd of 2.375.

Maybe a IGH internal lock-in slip triggers something in the BBS02B, that resets shortly after?

First order of business to understand what is happening is to take the IGH out of the loop and see if it still happens. Not sure how I can do that, I don't have a normal cassette with shifter to put on for testing. I do have a 7spd cassette that I currently have 5 of those cogs on my Velocity Dually cassette rear wheel, but no derailleur and shifter to operate it. I might ask around if any friends have a spare used setup I can test with on the cruiser without touching the BBS02B's internals to pinpoint the issue.

[calfee20]

Drive around in second. Your cadence would be to high but you could use your throttle. If it slips pedaling it will with the throttle to I imagine.

[Gr8fun]

I am running a sa 3 speed and cassette. As pictured in calfees post.
I have had a sa 3 speed slip out of gear, older type aw, foot would go down hard and loose grip on pedal. Ran over my foot. Ouch. Bad adjustment problem as described by sheldon brown. this has never happened on my SA csrk. Even when not in adjustment.

My problem is slightly different in that chain and front ring do not engage with motor. I am still in connection with chain and rear wheel. Sometimes from a stop. I can pedal this with no assistance from motor before it suddenly engages and i have power again.

I have no problem with getting power to the wheels with pedals, only with the motor putting power to crank.

[Rider]

I just thought of something worth checking. I will recheck my 3spd trigger shifter adjustment to see if it has moved or stretched. I used this Sheldon Brown method for setting up my Sturmey-Archer shifter.

This has got to be it! Check this paragraph out from Sheldon Brown's site:

"If you hold the trigger halfway between middle and high gear, the hub should disengage so that you can spin the pedals forward without going anywhere. If it freewheels forward in high gear, the cable is to tight or has too much friction to release properly. If it freewheels forward in middle gear, the cable is too loose."

I will go check that adjustment right now...

[calfee20]

Do you have a hollow axle with a pull chain?

[Rider]

I completely unscrewed my shifter adjuster and removed the plastic cover just in case the round lock nut was catching on the cover edge (pictured). I re-adjusted the shifter using the Sheldon Brown method. The cable is completely loose when in 3rd gear, so unless something is preventing it from returning all the way in it is clearly not too tight (which is what the quoted paragraph says causes what is happening). I rode it hard around my neighborhood in level 8 of 9 (the highest level I ever use now). I couldn't make it slip and free wheel, but it is so infrequent that I can't say that it is fixed. I will report back once I give it a solid 40-50 mile ride.

Yes, I have the hollow axle SA 3spd like pictured, but I never knew there was a colored mark on the chain. I put mine in 2nd gear, but there is no colored mark visible, so I shifted it into 1st which pulls the cable chain out the farthest. In 1st I can see a yellow mark on the chain just inside the edge of the cap nut (pictured).

Here's the thing, if I backed out the cable chain far enough to put the yellow mark where your instructions say it should be it would be way more than a 1/2 turn from bottomed out. Mine is backed out about 3/4 turn to get the cable chain in the proper position to slide on the nut edge correctly. When in 1st gear the chain can only move a little bit more if pulled by hand. When in 3rd gear the cable chain is completely slack; fully bottomed out via the internal spring.

How does your instructions say to set the screwed in shaft at the end of the cable chain inside the axle? Does it say to bottom it out, then back it off a certain amount?

[calfee20]

My picture isn't real clear. You are supposed to look through the hole in the axle nut to align the yellow with the end of the threaded axle. I just remembered from your photos that you have the same hub as me.

[Rider]

Okay, I will check it through the hole and see if I can even see the end of the axle. This SA hub is a CS-RK3 disc brake cassette model.

I'm leaning towards shifting under power from the BBS02B is causing "...or has too much friction to release properly...". Once in high gear and after pedaling for a time, it slips because it never went all the way in as a result of the friction caused by the electric motor. After the slip and free wheel without power, it settles into the proper position and all is fine.

If this thought proves correct, then maybe a stronger internal return spring and a gear shift sensor might help on all the SA IGH's when paired with an electric assist motor.

[calfee20]

I never shift under power.

[Rider]

I try not to, but the too long delay in power shutoff when you stop pedaling makes that difficult. I hoped to shorten the delay setting using the USB cable, but haven't got around to learning that software yet.

I ordered a "Y" cable and gear sensor shutoff today, so all use with the SA RX-RK5 5spd IGH will be with a gear sensor in place.

[Rider]

On today's ride it slipped twice after resetting the adjustments, so that didn't help. Oddly enough it happened in low level settings and not under any kind of hard pedaling. What I did notice is it wasn't too long after an upshift into 3rd. After the initial slip, it never seems to slip again while in that gear. It only seems to happen once after upshifting into 3rd. That makes me think if it is the hub it's due to the shift not getting all the way where it is supposed to be.

Tomorrow I will tighten the cable a little bit and see if that makes any difference. I will also check the yellow color stripe location as is and after I tighten it some. Then it's off on another test ride...

[Rider]

Checked the color mark as adjusted. It was a little inside the axle end, so I tightened it up so that the left side of the color mark is right on the axle end. Test rides around the neighborhood made me think this fixed it, because I couldn't get it to slip in 8 of 9 no matter how hard I tried. Unfortunately this morning's 30+ mile ride proved that not to be the case. It slipped 3 times today, but each time it slipped and grabbed again quickly; didn't free wheel like it has been. I think tightening the cable is possibly going in the right direction, so I may try tightening it a bit more and see what happens.

At this point I am 99% sure the problem I am encountering is a rear hub issue and not a BBS02-B issue. Like so many others have found out, all that extra power form the electric assist reeks havoc on bicycle parts that aren't designed for that much wattage.

My 20T cassette sprocket arrived today, so I will eventually put that on with a 42T or 46T front and test it in 2nd 1:1 gear locked position to see if anything slips. Can't really test 1:1 2nd with my current gearing because of the low gearing. There's not enough stress on the rear hub at 10-12mph and wound out on pedaling...

[Rider]

Today's 51 miler was so relaxing. Had no time constraints today, so took my time enjoying the ride and talking to people throughout it. Unfortunately the hub continues to slip at times, but with the adjustment set like calfee20's SA instructions state to align the colored mark, it is now a slip and quick grab instead of going into free wheel mode. There really isn't any more cable adjustment to tighten it up more. When shifted into 1st gear there isn't ANY slack left in the cable like the Sheldon Brown method states should be, but I'm going to go with the SA colored mark that probably wasn't on the older SA 3spd IGH hub chain. In 3rd the cable is slack and unrestricted, same a Sheldon Brown.

Met a guy on an electric skateboard that he was somehow involved with the design of. He claimed it would go 17mph and had a 3-4 hour battery life. The whole space between the wheels under the board was a battery pack and the wheels were larger and wider than normal skateboard wheels. He controlled the speed and brakes with a handheld remote control. The whole thing was kind of cool, although I'm way to old to play the skateboard game these days. I'll stick to my new found joy of E-bikes.

[Rider]

Gave my bike its' first real full cleaning and found something interesting. The rear hub and axle have some slop in it. This could be the source of the slipping. Either the end nuts have backed off some (unsure how that could happen?) or the bearings have worn in. Only pulling the rear wheel off and looking at the hub itself will tell me what's up. Have to do that before I continue riding it...

Also found my rack mounting bolts were loose. Pulled each one all the way out and put a dab of blue Loc-Tite on each before retightening them.

If you haven't given your bike a good once over in a while, I highly recommend it. Things do wear and come loose!

[calfee20]

My bike fell over on a windy day last year and landed hard on the slimline battery on top of my rack. This was before I got that double deck rack to protect the battery and be more useful. The fall snapped one of the 5mm X .80 rack bolts that are in the dropout. When I got home I drilled and retapped those holes to 6mm X 1.00.

All of the weight of the rack and what ever you have jammed into your luggage is held up by those two skinny bolts. I have been putting gallons of milk or even 12 paks of soda into those side panniers. That is to much weight for 5mm screws. That 6mm upgrade is going to be standard procedure for me now.

[Rider]

Good to know. I have to drill different location rack mount holes on my Electra Cruiser build, so I think going larger is in order. Even the seat post clamp front rack mount has large long blocks with those tiny screws, so drilling them out and re-tapping will get done at the same time.

The Soma frame is a bit frustrating in that they use American thread, not metric like just about every other bike part. If you aren't thinking and use a metric allen wrench on them you will quickly gum up the allen slot on the American bolts or if you try to thread a metric bolt into the American threads on the frame it's screwed up forever.

[Rider]

Popped the rear wheel off and found a new issue that may or may not be part of the original skipping problem. The lock nut knurled spacer on the disc brake side has cracked in half! The slop in the axle is very noticeable with the wheel off too.

Took the wheel to my LBS and he ordered up a new knurled lock nut and will adjust the hub bearings for me when it comes in. Should be good to go after that. Hopefully the slop is what is allowing the hub to slip, but we will see.

[Rider]

Electric motor TORQUE is causing a number of bicycle parts on everyone's bikes to fail!

Internal-Gear Hub Torque:

http://www.sheldonbrown.com/twist-internal.html

Sturmey-Archer Internal-Gear Hubs, Tech Tips:
http://www.sheldonbrown.com/sturmey-...rotationwasher

I'm running the "HMW534" anti-rotation washers on the outside next to the nut that came with my Sturmey-Archer RX-CS3 IGH hub on Soma vertical drops.

"Sintered, thick, with a single 9.5 mm wide tab. Same slippage issue as with the HMW518. Recommended by Sturmey-Archer for vertical dropouts."

Because people are blowing out bearings on cassettes, I'm going to check the bearings while I have this off the bike.

[Rider]

After reviewing those links, I think I will see if the "HMW494" with dual tabs will fit my Soma drops. If not, I might go to Paragon Rohloff drops with the longer drop slot and the HMW494 torque washers to hopefully eliminate axle rotation. The disc brake LEFT side is Paragon B4010, but I don't see a long slot derailleur RIGHT side.

Anyone know if Paragon or another producer makes a long slot derailleur RIGHT side sliding vertical drop?

[Rider]

Good news! The bearings looked like new inside, so I simply added a very small amount of grease right on the bearing race and buttoned it all back up. No more slop.

Now I'm waiting on the replacement knurled lock nut that cracked. ETA is Wednesday...

Found a pair of HMW494 dual tab torque washers on eBay from the UK for $2 plus $4 shipping, so I ordered those up for the future.