What do you think of this type of toqure arm

[bigisland]

I have seen this style torque arm on some thread here on ES and am wondering weather it is a good design?

Its a steel plate, for an aluminum frame, it has that tang that prevents it from rotating . (along with rack/fender bolts)

Questions I had

are slots ok as opposed to a double D hole for the axle?

Is the tang needed?

what about the fact that this design does not transfer any forces away from the drop out to the frame, as in the arm type?

I am thinking about this for a BMC V2T hub.


Thanks

 

[neptronix]

By the way, this is called a torque plate

Yes, this is one of the best designs you could really ask for, short of welding a custom rear to a bike.
I don't know what this 'tang' you are referring to is, lol
The left portion of each plate that doesn't bolt on to anything isn't very necessary. Two holes to mount to are what prevents the axle from moving.

Slots work fine. A hole where the axle bolts through is just more like extra insurance from the bolt coming loose and the wheel coming off than anything else. More difficult to cut out though.

 

[dogman dan]

The tang, the peg that fits in the v between the stays looks needed to me, unless some other way of securing the place is used.

A D hole can't spread, while an open dropout can. But make it fat enough, and it will likely be strong enough. Not if you are Methods, or LFP, but normal folks running 2000 watts or less it should hold.

A loose nut can still allow the wheel to leave the bike with an open design though. The ultimate torque plate designs use pinch dropouts.

 

[Drunkskunk]

Great Design! That tang needs some work, if the motor does start to spin, it may take the full power of the motor, and its small to be transferring that force effectively. it might shear off, or press into the frame, letting the axle shaft rotate, and breaking the dropout's legs.
I would make it bigger and contoured to the crotch of the frame. Flat surface to flat surface with the tang, and as tight a fit as possible. that way if your nuts fall off, you can keep your shaft were it belongs without breaking her legs.

 

[Gordo]

Maybe read what is written, and look a little closer at the picture;

"it has that tang that prevents it from rotating . (along with rack/fender bolts)
Two bolts plus the tang, keep it from rotating.

Not as good as a DD arm or a pinch bolt, but OK for most applications.

 

[neptronix]

my disc brake holes and rack mount holes on the other side seem to be working fine for me up to 2500w ( never took the amperage higher so i can't tell )

A 'tang" is just extra security. I think it just adds more complexity though.

 

[bigisland]

Neptronix, what do you got there looks like 1/4 " steel plate?

I think I need the pin up against the wheel stay because the threaded holes on my dropuots are cloes to the edge and the bolts seem thin I dont think theres enough metal around them.

I guess the best version would be just the plates with the doubble D holes that would have a more fitted "tang" and then you reall dont need to bolt them the axel nuts would hold them in place.

if your nuts fall off, you can keep your shaft were it belongs without breaking her legs.

Yes but you must then be in the hole.

Has any one filed out a doubbel D hole in like 3/16 steel.
with a file?

 

[neptronix]

Neptronix, what do you got there looks like 1/4 " steel plate?

Tow hitch.

I think I need the pin up against the wheel stay because the threaded holes on my dropuots are cloes to the edge and the bolts seem thin I dont think theres enough metal around them.

If you have disc brake holes, those work excellently. They are meant to handle a lot of torque by design.

Has any one filed out a doubbel D hole in like 3/16 steel.
with a file?

I think magudaman has such a thing for sale in the new/used section these days..

 

[bigisland]

Looks like hes not doin any more work,

What about doubbel D hole washers any body sell them?

 

[Drunkskunk]

Maybe read what is written, an look a little closer to the picture

I read. And I saw. and those rack mount holes wouldn't be enough on their own. I repair bikes for friends and strangers, and have seen plenty of those rack mount points destroied by too much force being applied. They are simply too close to the center of rotation. bigisland seems to understand that as he included that tang for extra support.

 

[bigisland]

On a bmc hub which way will the axel want to turn, opposite. The rotation of the wheel?

Thanks y

 

[Gordo]

On a bmc hub which way will the axel want to turn, opposite. The rotation of the wheel?

Thanks y

Opposite the rotation. Look at Neptronix's pictures. Brutally strong installation. Note the Nord-Lock washers under the axle nut. If you are worried about the plate tearing out both bolts and the pin, drill a 1/4" hole through the assembly and use a grade 8 capscrew.

 

[bigisland]

What does he got there I guess thats 1/4" steel?

I think the pin would hold for sure.

 

[dogman dan]

Pin would be fine, provided it was not soft steel. But a perfect fit would be cruicial. If it had room to wiggle, it would. Two bolts would be better than one bolt and one pin, simply because of an accurate fit. So a v shaped piece of steel, jammed into the space between the frame tubes would spread the load better to the frame, and could be bolted on in the position insuring a perfect, tight fit. Same concept as the tang or pin, but tighter fitting, and micro adjustable. You'd fit the V shaped plate to the installed torque plate, drill your holes, and bolt in in place for a perfect fit.

 

[bigisland]

Dogman do you think a V is necessary, would you be expecting movement in the plate in both colck wise and counter clock wise directions? I'm thinking something along these lines.