Idea for front forks torque arms.
- Thread starter ynot
- Start date
qwerkus said:
Those are both elegant in design.
They will not work on my front forks because there is not enough thread for full spindle penetration into the nut, I suspect that the dropouts on the bike are much thicker than is done on newer bikes, if I get a chance will put a caliper on them today and report back.
ynot said:
Yes so I've read in the topic. Do you have a picture ? If there is not enough space for 4mm stainless steel, than something got really wrong somewhere. Also, many chinese ebike nuts are way oversized. As a thumb rule, you need around the diameter of the axle for a nut to hold firmly, which means usually only 12mm. You can grind away anything above it.
qwerkus said:
Here are the numbers for the right side:
Clearance for wire measured from motor to inside drop out ......... 8.5mm
Thickness of drop out lugs.................................................. 11.2mm
total ........................................................................... 19.7mm
spindle length ................................................................ 28.5mm
Thread available for nut ................................................... 8.8 mm
Nut length .................................................................... 12mm
I no longer have my Marks engineering handbook but as I recall to achieve design strength requires 1.5 bolt diameters insertion into the nut. It is a 12mm diameter spindle so we are on the short end.
As you suggest have ground down the nut for that side so that the nylock engages the threat but makes it a little tough to tighten with a metric crescent wrench so need to keep a socket handy.
If I thought there was a good way to buy or make a more typical arrangement I would be thrilled.
Cheers and thanks for the input, I certainly would not mind being shown wrong, but so far..........................
motomech
10 MW
No kidding, it would have saved folks trying to helpful a lot of time.
Asides that it is some kind of "one-off" application, I'm still unclear what the he trying to mount the Jump motor on.
motomech said:
I need to get unlazy and go out and look at one, but based on the pics on the internet, it looks like Uber/Jump was able to get away with using short axles due to how they designed their front fork. It basically has a extra big pair of what they used to call lawyer lips on bicycle forks. Those made quick release hubs, slow, since the lips prevented the wheel from coming off when you flipped the quick release lever. The Uber fork has them extending past the nut, so the that's an extra safety feature since the wheel can't fall off unless the nut comes all the way off. Plus, it looks like they use a fairly stout/thick dropouts, like the OP's. I can see that the lawyer lips probably require a thin wall socket to get the nut off too, since the clearance looks pretty tight. Definitely stops someone with an open end wrench. I'll need to do a drive by and get a visual.
E-HP said:
Yep, I did not expect to need them until I started reading all the horror stories here and on other sites. So then started thinking about design.
You and many others here know a lot more about ebike electronics and forks, but have a long personal history of building machines for various industries from jewelry tools one of which I patented up to and including parts for the Vancouver sky train as well as ship loaders.
I bow to your knowledge, but can drive turnip trucks.
ynot said:
What would be cool is if some of the Mech-Es or material science experts could chime in with general rules of thumb on the thickness requirements of various materials (steel, titanium, tempered aluminum), that would allow a hub motor to go without torque arms. It could be something like:
40 N-M
Aluminum XXmm
Steel YYmm
Titanium ZZmm
80 N-M
etc.
I ran my 1000W motor briefly with not torque arms on my old steel frame, and there was no problem, but I added a cheap one later for insurance. The dropouts were maybe 8mm?
I think I've seen some pretty high power builds on this forum that used pretty thick aluminum clamping droputs.
And not only that but isn't that a 7-sided nut? Which would definitely stop someone with even a thinwall socket.E-HP said:
I see those bikes all day. Also often wondered what was that triple stoplight-looking thing with the little brass dishes facing forward, and also that security (tamper-proof) standoff screw looks like torx with a post in the middle?
E-HP said:
My copy of Marks Handbook for Mechanical Engineers pre dated Ebikes, but it did have tables giving the modulus of elasticity for various materials, with formulas so that the required dimensions could be established, these days there are so many alloys that did not exist then that trying to tabulate motor, fork, alloy combinations would be pretty steep.
motomech
10 MW
E-HP said:
The Jump motors are just standard Bafang SWX02 motors, same overall width as other frt. mount mini motors including the Q series and MXUS units that I have used.
With a pic at the start, this thread could have been 2 or 3 posts long, but this thread has wandered off in every direction except being specific about what the donor is so a specific solution could be put forth.
We been introduced to "freighter trikes", Delta trikes" and "Reverse trike's", "her Ladyship's 500 Watt Fat tire trike" and "an old iron clunker". He's all over the place and after two pages all I know about what he trying to do is it involves a Bafang SWX02 and ?.
I'm still unclear what he working on and trying to do, except it apparently needs an engineering evaluation using a Marks Engineering Handbook .
I'm wondering if we are being trolled.
E-HP said:
This kind of recessed dropout is what I figured by read the topic, hence the post about my torque arms. The spinner fork has the same issue, and if you grind it a little ("open the lower end") my torque arm works like a charm. A agree that this thread seems to be stumbling in the dark, but I think that we need a sticky thread about modern suspension forks + torque arms. It's a really problem in my opinion, and there are very little informations online, include ebikes.ca about how to find a solution. The whole idea was to make it impossible for the wheel to jump out of the fork while disc braking.
motomech
10 MW
Nobody ever looks at a sticky.
I think I covered the installation on alloy tube forks in post #10 w/ a link to the Ebike CA tutorial. That might have been an opportunity for the OP to say, No, that won't work because......
The only reason I'm still following this is I'm curious as to why his motor won't mount like 1000's out there have.
I think I covered the installation on alloy tube forks in post #10 w/ a link to the Ebike CA tutorial. That might have been an opportunity for the OP to say, No, that won't work because......
The only reason I'm still following this is I'm curious as to why his motor won't mount like 1000's out there have.
dogman dan
1 PW
Solve the problem with a different fork. But not because it will make the axle longer. Some of those old 250w motors were never designed to be used with a TA. And they were never designed to be used with a fat alloy fork, if that is the case here.
Good solid steel fork, grind off the lawyer lips so you don't need a c washer, tighten the nut good but not so much it strips.
Personally, I'd just chuck that motor, but I'm the guy that got free motors sent to me for years. Still pretty cheap though, to just get a motor with some axle length on it.
Good solid steel fork, grind off the lawyer lips so you don't need a c washer, tighten the nut good but not so much it strips.
Personally, I'd just chuck that motor, but I'm the guy that got free motors sent to me for years. Still pretty cheap though, to just get a motor with some axle length on it.
motomech said:
Pictures would be lovely dear, but I do not have that capability for a number of reasons.
So why bother taking the effort to reply to a thread that you think should have been over in two or three posts?.
I came here to learn and that has been very successful, now know volumes more about ebike, motors and torque arms than I did when I joined and thanks to all who have chimed in with both positive and negative responses.
For example due to this topic I have learned about clamping dropouts and have made and installed them on the trike am building.
One of the better comments was that my idea would tend to keep the wheel close to where it is supposed to be in the event of a broken dropout.
Chalo was helpful with information, but no one has given a reason to doubt that my simple idea is not a good one.
If the nut cannot move, or undo, the spindle will not move and the dropouts will not be overloaded.
We are not all at your level of expertise bike wise, but you and each of us can only develop our knowledge. over time.
I and perhaps others have learned from those who unstintingly gave their advice.
Voltron
1 MW
Yeah, this post turned into a pretty sad commentary about the state of ES.
When I first got here, it would have been people encouraging respect for the make it work attitude, instead of hey, just throw that motor away. Maybe I missed it, but did a single person that said there's no way the axle would be that short say "oh I get it, weird axle!" after seeing the picture? Because I sure thought that....
Instead it's turned into you're doing it wrong, just start over with a different motor, get another fork and throw that one away, you must be a dummy for not reading old posts about it despite the not always easy to use search, etc.
Plus just a general distain for a chatty attitude about a project, and complaints about not staying on topic, to the guy who can do whatever he wants with his own post!
When I first got here, it would have been people encouraging respect for the make it work attitude, instead of hey, just throw that motor away. Maybe I missed it, but did a single person that said there's no way the axle would be that short say "oh I get it, weird axle!" after seeing the picture? Because I sure thought that....
Instead it's turned into you're doing it wrong, just start over with a different motor, get another fork and throw that one away, you must be a dummy for not reading old posts about it despite the not always easy to use search, etc.
Plus just a general distain for a chatty attitude about a project, and complaints about not staying on topic, to the guy who can do whatever he wants with his own post!
Voltron
1 MW
So off topic 
Sorry ynot.
Near as I could tell, the black trafficlight thing is LED light assembly (the big basket blocks regular bar mount light), and the big stainless knob is for locking it into the docking station (matching one on the other side).
Sorry ynot.
Near as I could tell, the black trafficlight thing is LED light assembly (the big basket blocks regular bar mount light), and the big stainless knob is for locking it into the docking station (matching one on the other side).
