Hub motor install - freewheel & brake advice?

harmonist

10 W
Joined
Jul 10, 2016
Messages
66
Location
Auckland, NZ
Hi all,

Just starting on the install for my new Edge hub motor and have some first initial questions.

As you can see in this pic the rear brake caliper mechanism is rubbing against the motor, does that basically mean I can't have a rear disc brake and can only use regen? should I just buy a stealth style frame instead maybe? thats my long term plan.

1.jpg


I'ver never installed a new freewheel before, is there supposed to be an end piece on here that will tighten up against the frame?

2.jpg


Cheers!
 
Looks like I'll need some washers I guess to slot into that freewheel and space it out from the frame, every days a learning day :) https://endless-sphere.com/forums/viewtopic.php?f=3&t=36914
 
She's already a tight fit but I guess I could try what this guy did and push it out with washers, or else look at the thin mechanical caliper mentioned, guess that answers those questions :)
https://electricbikereview.com/forum/threads/brake-calliper-rubs-on-the-hub-motor.4206/
 
harmonist said:
Hi all,

Just starting on the install for my new Edge hub motor and have some first initial questions.

As you can see in this pic the rear brake caliper mechanism is rubbing against the motor, does that basically mean I can't have a rear disc brake and can only use regen? should I just buy a stealth style frame instead maybe? thats my long term plan.

1.jpg


I'ver never installed a new freewheel before, is there supposed to be an end piece on here that will tighten up against the frame?

2.jpg


Cheers!

Lots of issues here.
First off, the axle is not deep enough in the drop outs. You need to take a round file and file them deep enough that the "tab" of the "torque washer"goes down about flush w/ the drop-out opening. Not that we trust that "torque washer" to keep the axle from spinning in the drop-outs, we don't(more on that in a moment).
What you need to do is put that torque washer on the inside to move the hub housing slightly to the inside. To bring the disc back out to the caliper, get disc spacer(s);
http://www.ebikes.ca/diskspacer.html
That is just a single spacer, but the torque washer is probably the same thickness(measure to ck.), so it should work. There are also "kits" avail. w/ various thickness shims for more adjustability.
You also need two torque arms, one on each side for regen. Don't even try it out w/out them or you will be sorry;
http://www.ebikes.ca/shop/electric-bicycle-parts/torque-arms.html
Yeah, that is what a free wheel looks like. Basicly, you will need to add flat washers over the axle til they extend just past the free whl. edge so it won't rub on the inside of the drop-out.
Adding washers on the inside of both sides may require "spreading" the chain stay slightly. It's NBD and usually it can be done w/ your hands. If not, some careful prying w/ a flat-bladed screwdiver should do it. Moving the hub over may or may not move the tire/whl. off center-line. A slight amount may not effect the tracking adversely, but if you can see that it's too far to one side, you will need to move the rim by loosening the spokes and re-centerening it.
Lastly (for this element of your build), that looks to be a free whl. w/ a 13 T sm. gear. If you want to be able to pedal along at speeds above 15 mph, you need a DNP free whl. w/ an 11T sm. gear;
http://www.ebikes.ca/shop/electric-bicycle-parts/freewheels.html?SID=2202751269dcf8fa7d9226d2e39acc9e
If I were you, I would show us(in pic.s) the completed whl. install and any other elements of the build that you are not sure they are 100% correct. It can save you some money and heart-ache.
 
Brilliant thanks for that info momotech, much appreciated!

Haven't had much time to spend on it today but managed to check a few things out, turns out the wheel came with a few spacers so I've been able fit those on the freewheel side, had to spread the dropouts out a little but that was done by hand alright, the freewheel is a "DNP 7-speed Freewheel 11T-28T", so hopefully thats going to be all good pedaling with. I've also got 2 universal torque arms I'm planning on using for the build.

So the next issue it seems is going to be filing out the dropouts to make those spacers sit flush, heres some pics

Whole wheel

1.jpg


I filed a small amount but there's still about 6mm between that washer tab and the top of the dropout so I'd probably need to file up to 1cm before that tab would sit in the dropout

2.jpg


This would cause an issue where the nut and torque arms won't fit because they would come into contact with those rear arm welds, so the question is, is it essential to have those washers sit all the way in the dropout?

3.jpg


Would that be an acceptable torque arm layout?
4.jpg
 
The torque arm on the pivoting link will want to move with the link as it pivots/moves relative to the swing-arm with the axle/dropouts. You would do better by flipping it over to connect to the same fixed part as the axle instead.

Here's a quick example of the forces that will be exerted on the axle and torque arm like that:
file.jpeg
 
I've got this plastic part that came with the wheel, could I use that as a disc spacer or does it really need to be metal?

Cheers

5.jpg
 
Yes, I see that the space around the drop-out is tight. Still, I would like to see the axle down in there a little deeper, the more "meat" around the axle, the better. What I would do is to take a Dremel tool w/ a standard abrasive cut-off wheel and go straight in(like you are boring it) and see if you can gain a little more clearance and a truely flat surface for the hardware to sit on. Obviously, you don't want to remove much metal, but you should be able to get the axle down in at least a couple milimeters more. Kind of 'splitting the difference", a judgement call. I would also smooth out any sharp edges left by the "clearancing".
The torque arm mounting looks good, the torque on it will push against the chain stay, the way it should be. I would add a couple of flat washers to the pivot nut and make sure it is tight, tight, tight(thread locker liquid-axle nuts too).
If you will ever be in any water, I would suggest to get more of a loop in the cable, the idea being water won't run down the cable and possibly enter the hole.
I know that tire well, used them off and on for years. The CST is a good value tire that is thick enough to resist flats. I recently switched to Crazy Bob's, a better tire, but twice the price.
I am also famiular w/. the torque arm;
100_0066.JPG
..and it's a little expensive to call it "universal" :wink: You may notice the only way I could make mine work is to have pull away from the chain stay, but no regen on my low-powered motor and I have a TA on the other side as well;

Do you have another one like it for the other side and how is that going?
 
I'll note that in motomech's picture the torque arm is connected to the same "arm" that the dropout is part of, and not the pivoting part.

You may want to see if you can use the torque arm on the chain side like motomech did since you may have trouble clearing the caliper on the brake side when connecting to the non-pivoting arm (relative to your axle) of your swingarm.
 
zro-1 said:
The torque arm on the pivoting link will want to move with the link as it pivots/moves relative to the swing-arm with the axle/dropouts. You would do better by flipping it over to connect to the same fixed part as the axle instead.

Here's a quick example of the forces that will be exerted on the axle and torque arm like that:
file.jpeg
I don't think the two-piece chain stay connection pivots. That's the type of hardware that is a hollow bolt.
 
harmonist said:
I've got this plastic part that came with the wheel, could I use that as a disc spacer or does it really need to be metal?

Cheers

5.jpg
That's a spacer and will work if the thickness is right.
 
As always, there are different schools of thought...

That dropout is pretty problematic for a hub motor, shallow slot, unequal sides to the slot, aluminum, and little material around the slot.

Although it's always good to get a deep fit, the slot itself is just there to retain the axle and support the weight of the bike - the TA is there to address the business of rotation. I would lean towards retaining as much meat around the slot as possible. I would recommend just reshaping the bottom of the dropout slot without really making it deeper - also paying particular attention to avoiding a sharp corner in the dropout bottom. Here's a post with some hints that may be useful: https://endless-sphere.com/forums/viewtopic.php?f=3&t=92926&p=1359674#p1359674

MM's illustration about the forces on the components is spot on. Here it's important to realize that you have a reasonably powerful motor and that the torque from the motor is counter to wheel rotation. Although the generic TA setup looks okay in principle, I am always concerned about orientations where motor torque primarily tries to slide the articulated piece of the TA down a stay and where it's held in place only by hose clamps. Hose clamps work pretty well for forces applied perpendicular to the stay, but when the force is in line with the stay, you are in danger of the clamps simply sliding along. If we assume that at some point the clamps may loosen or work free a bit, in the perpendicular case, not much happens - the TA displaces a small amount. On the other hand, in the sliding case, the failure is more catastrophic.

So - use at least two very good quality hose clamps.

My preference would instead be to rearrange the axle part of the generic TA, then grab a bit of 1/8" steel flat stock from the hardware store and shoot a few holes like so. The will counter axle rotation with little tendency for the slotted parts to slide and gets that funky bolted stay joint out of the picture as well. Here you may need to put a washer between the two TA pieces if there is a gap when clamped flat by tightening the axle and brake bolts. You may need an axle washer under the TA to lift it over the shoulder in the casting. You might need a couple of longer 6mm brake bolts - also from the hardware store (Ace).

Anyhow, just some thoughts....


alternateTA_800.jpg
 
motomech said:
harmonist said:
I've got this plastic part that came with the wheel, could I use that as a disc spacer or does it really need to be metal?

Cheers

5.jpg
That's a spacer and will work if the thickness is right.

I had a similar spacer and found that it was a bit too thick. I just made my own out of a piece of thin aluminum as is commonly available from hardware stores. I suppose you could probably also use six small steel washer as well if you didn't want to wait for for a shim to get shipped.
 
Thanks for the feedback and suggestions everyone, super helpful and hopefully will prevent some breakages or injury!

I did some more grinding of the dropouts, the axle sits in there flush now but still not much deeper than before, but making progress.

1.jpg

2.jpg


I'll definitely look at getting a piece made up and bolt it on that side like you suggest teklektik, thanks for pointing out the possibility of it sliding using hose clamps, hadn't thought of that! In the meantime I've got them bolted on like so..

4.jpg


I bolted the controller onto the drink bottle screws and plugged it all in (minus cycle analyst) just to see it all spin up and take a slow ride and its working nicely, it has a real nice throttle, very smooth compared to the BBSHD which seems quite jerky now.

Appreciate all the input from everyone! just need to sort out the brakes and finish off the install, the only other question I have at the moment is the shifters, if using a right hand throttle do people move them to the left side? my shifters are on the right so I've had to slide them in on the bars so they don't bang on the throttle parts, I guess I could get a left hand throttle as a solution but it does feel more natural having it on the right side..

6.jpg
 
That looks great. Bur regarding the plastic spacer for the disc rotor, its just there to keep the bolts from sticking in too far to the motor case when there is no rotor mounted. They are too squishy to actually mount the rotor.. the bolts just start wiggling around as they can't be torqued right. It needs to be a metal spacer.
 
Re the shifters, it can be a pain getting a setup you like. It looks like your throttle has the on off and three speed stuff mounted on it? Sometime moving the switches someplace else and getting a lower profile twist grip one can work.
I ended up with a twist 8 speed and a thumb 3 speed so all my shifting it on the left as I couldn't work out a combo I liked with the brakes levers... sometimes getting used to left throttle is the easy way out...lol.



shifters.jpg
 
Looking good. Seating on the axle looks much better.

Not sure if that's just a test fit, but you might like to invert the controller so water runs out of the multiwire grommet instead of getting driven in by the airflow. The best seal is the one that doesn't have to seal...

On the matter of brake screws - if the screws are too long they can break out the casting on the inside of the motor when you torque them down. Check the screw length by running them down finger-tight with spacers in place but no disk - (the missing disk gives a couple of mm of clearance). If the heads hit, you are good to go. If they bottom before the heads hit you may need a washer on the outside of the disk or shorter screws. You seem to have the disk mounted up already, so the stock screws were probably okay, but if you swap screws because of the spacers, give it a check.
 
Voltron said:
Re the shifters, it can be a pain getting a setup you like.
What he said ^^^^^

Here's a setup with a Magura throttle, SRAM X3.0 trigger shifter, and Tektro 4-finger brakes. The controller kill button is mounted where your thumb is with the throttle closed. The controls are bigger and perhaps reminiscent of motorcycle stuff, but they fit together well and are comfy to use - for me.

throttleBrakeShifter.jpg
 
Oh of course, I hadn't thought about getting a throttle without switches attached which this one has, I'll do that and move the switches to the left side, cheers for that!

Yip that was just a test fit but that's good to know thanks teklektik, it'll be nice to tidy up all that wiring so its not visible.

Yeah it looks like the stock screws were all good, I've left the disc mounted for now and didn't end up using the plastic spacer, if I ever need a spacer I'll be sure to use a metal one.

Thanks all, you've saved me a heap of mucking around! :)
 
teklektik said:
Voltron said:
Re the shifters, it can be a pain getting a setup you like.
What he said ^^^^^

Here's a setup with a Magura throttle, SRAM X3.0 trigger shifter, and Tektro 4-finger brakes. The controller kill button is mounted where your thumb is with the throttle closed. The controls are bigger and perhaps reminiscent of motorcycle stuff, but they fit together well and are comfy to use - for me.

throttleBrakeShifter.jpg

ooh thats a nice looking set up, will look into that :)
 
Since I don't use the chain ring shifter, I pull the whole thing off and use a left-hand, half-twist throttle. There is no "getting used to it period" as the brain adapts to it right away. HL, HT throttles can be purchased from Grin or Luna in the States and BMS Battery in China. Left hand thumb throttles are now avail.from BMS Battery, but I just turn the reg. thumb up-side down.
Getting rid of the frt. derailleur can allow the chain to "jump off", but since I always go to a bigger big chain ring, it tensions the chain more and it won't jump off.
Here's a tip on using the DNP, because of the shape of the teeth, shifting can be improved if the derailleur is repositioned further up and under the free wheel. It can be seen in the pic in my post above.
 
Looks like you got most of it sorted. Kind of hard to install a motor on a better bike.

Even though solved, a few thoughts.

The plastic disk spacer is not too thick, if you put the same size spacer on the axle itself. Plastic can also be shaved thinner with a sander.

Re filing the dropout deeper, I always aim for centering the axle in the notch same as the old wheel. this lines up the disk same as it was, up and down. So the caliper grabs the disc with the whole pad again.

For me, the best solution for throttles and shifters is the trigger type shifter. It needs 10 mm or so of space on the handlebar between the handle body and the throttle body. Sometimes this results in a short grip, but you can jam a broomstick in the bar to lengthen it an inch if its really too short.

After that, just converting to an old school handlebar mounted friction shifter can work fine. Depends on the use of the bike, but on street you do tend to put it in one gear forever, usually the highest gear.

With twist shifters, I like to remove the front derailleur or swap to friction shifter on the front. Then put the twist shifter for the rear on the left. Upside down, but works fine. This works REALLY good!
 
FWIW: When fabbing stuff like that TA bar above where you need to transfer hole layout, I find having some setscrews on hand helps get holes centered pretty painlessly.

There I would shoot the TA connecting hole at the end of the bar, put a strip of masking tape on the inside bar face against the brake mounting bosses, and bolt it up so it is aligned properly. Then run a couple of 6mm x 12mm setscrews into the brake adapter and press it into the bosses to mark the tape on the bar with the setscrew points. Center punch the impressions and drill. Done.

If you're doing it some other way, the brake boss holes are 51mm center to center if you want to check your layout.


conePointSetScrews.png
 
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