E-bike without rear disc mount

[Smurf2]

Not sure what you talking which thin disc tab :/

Rear brake can't lock wheel in breaking:
I bought lower adapter (it says 180/160 like already have, but it is lower). Placed washers from above and sides and longer screws. Now I think that pads are cover the entire surface on disc.

It breaking, but still on break I can't lock rear wheel on asphalt, which means that I not have 100% stoping power (Note that Zoom brakes have double pistons). Right brake handle still have 25% space between.

Also, I asked here about not full coverege pads and did not get answer of you. So I continue drive like this and
after 100km of drive with no full cover pads on disc, I got this shape on pads, like on picture, not same, but similar.

Where is problem? In this video he can lock wheel with Zoom mechanical disc brakes easy.
VIDEO

Is my fake? Must I clean disc? Must drive it more? I can change new Zoom pads before install front brake, but think will be same.

 

[SlowCo]

Rear brake can't lock wheel in breaking

Also, I asked here about not full coverege pads and did not get answer of you. So I continue drive like this and
after 100km of drive with no full cover pads on disc, I got this shape on pads, like on picture, not same, but similar.

Where is problem?


I can change new Zoom pads before install front brake, but think will be same.



View attachment 343070

Now that you have the brake pads covering the whole disc area and the the whole pad area you need the brake pads to be flat. By first riding and braking with the pads above the disc you have worn them uneven. Now only the top of the brake pad that is sticking out is touching the disc instead of the whole pad area. So new brake pads would be the best solution.

 

[glennb]

Those adapters are thin. You could triple them up, as in three on each side. Or use one as a template to simplify making new ones from thicker material.

 

[docw009]

Are you using the beveled washers under the caliper, or flat washers? They beveled washers allow the caliper to better match the plane of the rotor, although ideally the rotor is at 90 degrees to the bike frame.

The classic instructions are to loosen the caliper mount screws, pull the brake levers so the caliper grips the rotor, and then tighten the mount screws, If these are hydraulic, you;re done with adjustments,

You should be able to get the washers at a bike shop for a lot kess thanwhat they charge online.

 

[lnanek]

Might also want to tighten the brake line in case your lever isn't pulling enough cable to fully close the brake calipers. Many brake levers also have a pivot point adjustment you can use to select more pull.

 

[Chalo]

Might also want to tighten the brake line in case your lever isn't pulling enough cable to fully close the brake calipers. Many brake levers also have a pivot point adjustment you can use to select more pull.

Also, if you're using e-brake levers, those don't usually pull enough cable for V-brakes or mechanical discs. That can exaggerate the effects of any brake adjustment issues.

 

[Smurf2]

@docw009
I'm using a normal flat washer.

@Chalo
No. I'm using original V-brake lever (with brake sensor for e-brakes).

@Inanek
I know that all.
Anyway, I said that pads full closed when press about 75% of brake lever. Other 25% not using and can be for further wear adjustment.

Now I swap front and back pads, to see how it will be.

Front wheel:
I bought other beautifully used double wall rim and just installed front wheel brake.

When rotate disc, it scrapes at one place in caliper.
Is it possible that brand-new rotor can be bent? The rim going just little left/right, but more up/down. (I watched truing wheel tutorial).

Because of that, caliper adjusting method with press lever and tighten caliper not work there.

I adjusted it in other way (without pressing lever). Tighten caliper piston to the rotor, then loose piston until scrapes sound stop. Repeat other side. Good?

I will try it in morning.

 

[99t4]

Is it possible that brand-new rotor can be bent?

Yes. Most common rotors are thin metal and can easily bend or warp. It can even happen when installing or removing the wheel, if you are not careful to precisely align the rotor straight into the caliper when installing or removing the wheel.

 

[Chalo]

Yes. Most common rotors are thin metal and can easily bend or warp. It can even happen when installing or removing the wheel, if you are not careful to precisely align the rotor straight into the caliper when installing or removing the wheel.

Also, neither the new rotor nor the hub mounting surface is held to any standard of flatness.

 

[Smurf2]

Ok. Disc brakes was finished on booth wheels. I will see how braking will be and do I need to change something.

glennb said:
Those adapters are thin. You could triple them up, as in three on each side.

Which adapter you mean? The small adapter between fork mount and caliper, or big bracket with mounting holes?

Also, can that big adapter serve me like a torque arm? It seems that, because adapter have hole for axis, and because it's holding on top and pressing it from booth side tight, wheel axis can't go down. Is that enough?

 

[glennb]

The flat plate adapter. The issue is the tiniest of accidental knocks will bend it. Yes, you can promise yourself you’ll be careful to avoid bumping it, but it’ll still inevitably happen.

Yes, such a plate could easily serve both functions as torque resistor and disc brake mount.

 

[99t4]

Also, can that big adapter serve me like a torque arm? It seems that, because adapter have hole for axis, and because it's holding on top and pressing it from booth side tight, wheel axis can't go down. Is that enough?

The TA main job is to keep the axle from spinning in the dropouts. The hole has to tightly match the profile of the axle (so not simply round). Secondary job can be keeping the axle (and wheel) from falling out.

Torque Arms - Grin Products - Product Info

For every force there is an equal and opposite force, and for every torque there is an equal and opposite torque. Sadly with import hub motors this opposing torque is often born entirely by bicycle dropouts that are not up to the task, allowing the motor axle to spin out. Grin has pioneered the...

ebikes.ca

torque arm picture thread

Cross-posting these two threads so a search will turn up both: "Found an awesome torque arm" (3 pages) https://endless-sphere.com/forums/viewtopic.php?f=1&t=11570 xxxxxxxxxxxxxxxxxxxx Original thread died. Figured I'd help out and repost what I saved. Here is the album link...

endless-sphere.com

 

[docw009]

The shiny plate on these adapters is like ,10 inch steel. Too thin to work as a torque plate. If they are braced against the dropout, a torque arm can be placed on the axle, and the resulting assembly is pretty rigid, being clamped to the frame between the nut and motor.

 

[glennb]

Doc’s idea’s are always good, and this one’s no exception. Definitely less effort to fabricate a torque plate that braces the thin plate, than to replicate the existing one in a thicker steel. Mainly because it can be rougher. For the required bracing the new piece needs to span both horizontal brake mounting bolts in addition to the axle, but requires very little precision. A triangle with thee holes, essentially.

 

[Smurf2]

Oh, didn't know that is prevent rotate axies main job of TA.

At #POST 78 you can see my first and thin DIY torque arm, but if I want to place it now, must drill two holes in adapter.

I also bought a new torque arm (thicker),
and not sure that it fit on my bike.

But, I have from both sides insalled already this washers which have that tight shape for anti-rotate axle. Can that prevent axle rotating too?

 

[99t4]

I also bought a new torque arm (thicker),
and not sure that it fit on my bike.

Garbage. A poorly excecuted copy of an originally flawed design, that the original manufacturer/designer discontinued several years ago.

Did you read the link I provided in post #62?

"TorqArm_V1 / DISCONTINUED

We developed our first attempt at a 'universal' torque arm design in late 2009. In this model, the arm part was attached to the fork with a single hose clamp, and the the axle plate could pivot to fit different dropout slot angles. When the motor is powered, it tends to rotate the plate clockwise, and with the pivot point on the back this causes it to further 'push' the axle up deeper in the dropout. Notice that if the torque arm is mounted backwards, on the front side of the fork, then it would have the opposite effect and axle torque would tend to pop the wheel out of the dropout.

While this design did work and was an improvement over no arm, we ran into failures from the hose clamp in cases where a motor controller had shorted mosfets. The curved hose clamp slot in this design put stress concentration points on the clamp which facilitated the hose clamp tearing in half. As well the contact point to the fork was prone to sliding downwards. As a result we discontinued manufacturing this model in 2010 and do not recommend its usage. There are of course now countless Chinese clones of this bad design being sold by clueless people all over the world."
(Bold italics mine)

From

Torque Arms - Grin Products - Product Info

For every force there is an equal and opposite force, and for every torque there is an equal and opposite torque. Sadly with import hub motors this opposing torque is often born entirely by bicycle dropouts that are not up to the task, allowing the motor axle to spin out. Grin has pioneered the...

ebikes.ca

But, I have from both sides insalled already this washers which have that tight shape for anti-rotate axle. Can that prevent axle rotating too?
View attachment 343279

Minimally helpful, only slightly better than nothing.

 

[Chalo]

Minimally helpful, only slightly better than nothing.

Two tabbed washers that fit closely to the axle flats are much more effective than sloppy loose-fitting torque arms, in my experience. But they're only as effective as the strength of the dropouts or fork tips. I've witnessed one failure in a bike I built, and one in a bike I coached somebody through. Those fork tips seemed okay, but were made out of cheese.