It'd be easier for a device to deliver motor power via the throttle control, responding to a torque sensor. But it'd probably ride like cr*p without a lot of fine tuning, and even then.
Kona Ute tsdz2 conversion
- Thread starter potato
- Start date
Aha? And hmmm... (translated)
Funktionsprinzip BAFANG Drehmomentsensor
Ich habe schon lange mit der Sezierung eines BAFANG-Drehmomentsensors geliebäugelt. Freundlicherweise hat mir @mechaniker mit seinen China-Connections einen beschaffen können, vielen Dank dafür! (y) Zu einem entsprechenden Preis kann er auch als offizielles Ersatzteil über den Fachhandel bezogen...
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Funktionsprinzip BAFANG Drehmomentsensor
Hallo, habe heute den Spider von @Hochsitzcola bekommen. Vielen Dank dafür! Der Sensor scheint bei meinem Fahrrad (Fischer EM1726) trotzdem nur das Speed/Pas Signal zu verarbeiten, obwohl ich die mV vom Drehmoment im BafangTool abrufen kann. Egal was ich im Torque Tool einstelle, der Motor...
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Back with an update. After 60 miles of shakedown riding I lent the bike to a friend to use for a bit whilst my kid grows enough to fit the seat 
Said friend has zero mechanical sympathy or interest in maintenance so I figured it would be a good test to make sure it was proof against my wife using it.
It's come back with another 160 miles on the clock, a big old creak and a cheesed thread on the axle. I guess most of it's my fault, I didn't gorilla up the crank arm bolt enough during the initial assembly and it rode lose, and once these ride loose once, you're stuffed in my experience.
New axle time for me and see if I can find the source of the creak on the way through, sounds like a dead BB bearing would on a normal bike.
Said friend has zero mechanical sympathy or interest in maintenance so I figured it would be a good test to make sure it was proof against my wife using it.
It's come back with another 160 miles on the clock, a big old creak and a cheesed thread on the axle. I guess most of it's my fault, I didn't gorilla up the crank arm bolt enough during the initial assembly and it rode lose, and once these ride loose once, you're stuffed in my experience.
New axle time for me and see if I can find the source of the creak on the way through, sounds like a dead BB bearing would on a normal bike.
Check for side play in the motor axle and is the motor tight in the bb try re-tapping the thread and locktite
After disassembling it, it was apparent the motor + bearings were fine, just loose crank bolt on the square taper axle had completely nuked the crank arm. I only had a small torque wrench (up to 24nm) so guessed, and seemingly I didn't guess very well.
That said.. one new crank arm later, and a torque wrench with the appropriate range, did it up to 40nm and the cranks are so tight on they won't even turn! hmmmm. Can't see that I could have cocked up anything in the reassembly on - black spacer plate, castle nut using the supplied tool, then crank arm...
Any thoughts? I'm going to back it undo it and try it again at whatever turns out to be the highest torque setting I can manage without it binding.
That said.. one new crank arm later, and a torque wrench with the appropriate range, did it up to 40nm and the cranks are so tight on they won't even turn! hmmmm. Can't see that I could have cocked up anything in the reassembly on - black spacer plate, castle nut using the supplied tool, then crank arm...
Any thoughts? I'm going to back it undo it and try it again at whatever turns out to be the highest torque setting I can manage without it binding.
The crank arm castings are poor on the square taper, once it has come loose [a very common problem] they tighten on to far up the shaft
Try to remove /file the rear of the crank arm to gain clearance if its the non drive side try a different arm
Try to remove /file the rear of the crank arm to gain clearance if its the non drive side try a different arm
Hmm. It's the non drive side arm I've replaced. I hope I haven't over torqued it and goosed the new arm! If the tolerance on the axle is the issue maybe a smear of loctite or grease might cause it to nip up just that fraction earlier.. Thinking aloud
If there's binding then there is contact in the wrong place, assuming axle not bent. Find and resolve the contact, hopefully amicably, and then full proper torque. Shouldn't be any need for less, if proper clearances have been restored.
??? "TongSheng TSDZ2 cranks have a lot of offset which increases the q factor well beyond what was intended for most bikes. "
TSDZ2 Replacement Cranks
TongSheng TSDZ2 cranks have a lot of offset which increases the q factor well beyond what was intended for most bikes. These cranks - Electrify Bike
www.electrifybike.com
- When I did my first TSDZ2 conversion (on my own bike) I tightened the cranks by hand to what I considered as tight enough but as experienced by others, they still periodically required re-tightening.
- One recommendation was to try Bafang cranks which I did but they loosened up after a while too, albeit maybe not so often.
- And then I bought a torque wrench and realised that 'my tight' was quite a bit short of the recommended 40nm torque. Now they are tightened properly: I checked the tightness after a further 1500km-ish (this is still with the Bafang cranks fitted) and I needed to give them a bit of a tweak, but otherwise OK
- Most casual cyclist don't know about this parameter and in practical terms I wouldn't think they need to as the factor is IMHO only likely to be a consideration for performance cyclists i.e. road racers.
- Of the 4 other TSDZ2 conversions I've now done (a) I've stuck with the original cranks and (b) I've tightened them up to 40nm and none of the riders have (yet?) to get loose cranks or any physiological issues that could be put down to Q factor.
Fresh look at it today and it all becomes clear, I have a friday afternoon axle.
Drive side - fine
Slightly blurry non drive side - no flats for the arm to seat onto before it binds.
Not impressed with the quality of this kit so far with the original crank arms not being threaded correctly and now this.
Drive side - fine
Slightly blurry non drive side - no flats for the arm to seat onto before it binds.
Not impressed with the quality of this kit so far with the original crank arms not being threaded correctly and now this.
- Clearly @potato you are having some issues with your TSDZ2
- Your observations got me curious as to what my axle tapered ends looked like so I took the TSDZ2 crank arms of my wife's conversion (I've removed them several times as I've moved the motor between three different bikes).
- As per your own observation, the taper on the non-drive side didn't have a 'shoulder' either but I've not had a crank arm problem.
- I don't think the presence or absence of a 'shoulder' is relevant - as long as the taper is machined to the correct angle and is long enough to allow the crank to be pulled onto the taper far enough that is tight, then all should be fine.
- In the two pics below you can see that the cranks on both sides have a small clearance between the motor body and the crank which supports my view that the shoulder (or its absence) might not be the issue.
- In your post #66 you mentioned that you'd tightened up to 40nm and the crank wouldn't turn.
- That experience rings a bell with me in that on one of my motors I thought the sprag clutch was playing up (it turned out to be fine - the probelm was the free-hub on the wheel), so I dismantled that side of the motor.
- On re-assembly I got something out of kilter and I had the same 'crank arm binding' issue that you describe and this was due to something I'd not got right in the re-assembly process (can't remember what it was though!) meaning the axle wasn't protruding from the motor body enough to allow full tightening on the taper (does that make sesne?).
Attachments
View attachment 46465
- Clearly @potato you are having some issues with your TSDZ2
- Your observations got me curious as to what my axle tapered ends looked like so I took the TSDZ2 crank arms of my wife's conversion (I've removed them several times as I've moved the motor between three different bikes).
- As per your own observation, the taper on the non-drive side didn't have a 'shoulder' either but I've not had a crank arm problem.
- I don't think the presence or absence of a 'shoulder' is relevant - as long as the taper is machined to the correct angle and is long enough to allow the crank to be pulled onto the taper far enough that is tight, then all should be fine.
- In the two pics below you can see that the cranks on both sides have a small clearance between the motor body and the crank which supports my view that the shoulder (or its absence) might not be the issue.
- In your post #66 you mentioned that you'd tightened up to 40nm and the crank wouldn't turn.
- That experience rings a bell with me in that on one of my motors I thought the sprag clutch was playing up (it turned out to be fine - the probelm was the free-hub on the wheel), so I dismantled that side of the motor.
- On re-assembly I got something out of kilter and I had the same 'crank arm binding' issue that you describe and this was due to something I'd not got right in the re-assembly process (can't remember what it was though!) meaning the axle wasn't protruding from the motor body enough to allow full tightening on the taper (does that make sesne?).
View attachment 46464
Thank you for going to that effort, I appreciate it. I agree that the presence or not of a shoulder is irrelevant so long as the taper is correct. I measured the largest exposed bit of the axle on the non drive side as 31.8mm. The other side I didn't measure as I thought I'd cracked it with the absence of a shoulder. Time for me to have another look and as you say, see if there's anything to get more axle showing on the non drive side
Hi @potato
I've just reviewed how I did the sprag clutch work/inspection (as per how the guy did it in this youtube clip here) and the dis-assembly is on the drive side of the motor so my earlier comment about having crank binding on the NDS after re-assembly is incorrect - my crank binding was on the drive side - durgh!
Apologies for any misdirection
I've just reviewed how I did the sprag clutch work/inspection (as per how the guy did it in this youtube clip here) and the dis-assembly is on the drive side of the motor so my earlier comment about having crank binding on the NDS after re-assembly is incorrect - my crank binding was on the drive side - durgh!
Apologies for any misdirection
I sent a video of the issue to the seller and they've said its because I'm using steps crank arms rather than the originals (which arrived with virtually no thread in the pedal holes). I don't really buy this as an answer unless they decided to make up their own axle standard, but with the language barrier making it hard to escalate, I'm waiting on a replacement set of cranks to try. Fair play to them they have sent the replacements out promptly, and without any extra cost for shipping or anything
It's too early for bodges, hope the newcrank arms work out... but if they don't - adding a dot of weld to the axle could leave that crank arm loose, which over time would wear away the axle and square hole in the crank arm. Also the heat from welding could affect the axle steel, depending on how much carbon it contains (and whether it's been folded and battered 200 times , Samurai sword style) and how it's cooled afterards - quenched in water could make it more brittle, which could lead to it breaking under stress. Allowing it to cool slowly could it leave it soft, which could lead to it bending. Filling in the square in the crank arm with weld to drill and file to form a smaller square, could also lead to bending, breaking or excessive wear problems, depending on how it was cooled afterwards. If those new crank arm didn't fit properly, I'd file off about 1mm from the motor facing side of that crank arm, hoping that it wouldn't make too much of a difference to it's strength. A somewhat risky bodge.
, Samurai sword style) and how it's cooled afterards - quenched in water could make it more brittle, which could lead to it breaking under stress. Allowing it to cool slowly could it leave it soft, which could lead to it bending. Filling in the square in the crank arm with weld to drill and file to form a smaller square, could also lead to bending, breaking or excessive wear problems, depending on how it was cooled afterwards. If those new crank arm didn't fit properly, I'd file off about 1mm from the motor facing side of that crank arm, hoping that it wouldn't make too much of a difference to it's strength. A somewhat risky bodge.
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