Scott Scale 950 - Torque Arm solutions?

[bonbond]

Hi there

I'm on the verge of building my first eBike, it all seems to stack up nicely, but I'm thinking about my options as far as torque arms go. I was wondering if anybody here had any bright ideas or had converted the same bike (as per title, a Scott Scale 950)?

Essentially, I'm looking at a running a 1500-2000W rear hub from 58V and I'm unconvinced by ugly 'generic' torque arms. I'm not a fan of jubilee clips and would like to avoid them if at all possible....

Photos below show the dropouts I'm dealing with.

The only real options I can see are to attach a custom built torque arm to the caliper mounts which would need to come over the top of the chain stays and/or possibly just bolt through the derailleur hanger attachment on the other side. The first option feels overly complex and far from brilliant mechanically.

Am I over-thinking this? I may be overreacting to the jubilee clip solution...

Anyway, any advice, experience or thoughts would be much appreciated.

Cheers

 

[Tommm]

That frame is one of the more difficult ones to make a torque arm for. No screw holes for derailleur on one side. No side facing brake adapter holes on the other.

I am not convinced by universal torque arms either. I just don't get it why the bolt joint connecting the two parts wouldn't just spin instead of transmitting the torque to the longer arm piece.

 

[E-HP]

Grin's torque arms are pretty well machined, or at least a lot better than the generic stamped steel ones. They fit pretty tight on the axle flats, but I wedged a piece of razor blade in between it and my axle flat so there's no movement at all, even with using regen.


https://www.ebikes.ca/shop/electric-bicycle-parts/torque-arms/torqarm-v4.html#

 

[Tommm]

Grin's torque arms are pretty well machined, or at least a lot better than the generic stamped steel ones. They fit pretty tight on the axle flats, but I wedged a piece of razor blade in between it and my axle flat so there's no movement at all, even with using regen.
grin.jpg

https://www.ebikes.ca/shop/electric-bicycle-parts/torque-arms/torqarm-v4.html#

Good shout on the blade idea. I got a box cutter that is ready to go.

 

[goatman]

maybe try torque arm v2 on deraileur side

https://www.ebikes.ca/product-info/torque-arms.html

 

[bonbond]

Thanks all.

So the general consensus is that that attaching torque arms to frame via jubilee clips/hose clamps is the norm and not a bodge? I'm just looking for clean build really, but above that I obviously want to build something which is mechanically sound.

I can live with the jubilee clips if that's the right solution...

So aside from the jubilee clip/hose clamp sentiments, do you folks think this frame can work, or am I looking at something which is inherently compromised mechanically?

Attaching a generic torque arm to the derailleur side looks like the simplest solution, but do you think the drop outs on the other side are deep enough for a second torque arm though (either another generic one, a modified generic one, or custom cut one)?

Again, just concerned about mechanical viability here - I want to build something that's safe and doesn't destroy the frame.

Cheers

 

[E-HP]

So aside from the jubilee clip/hose clamp sentiments, do you folks think this frame can work, or am I looking at something which is inherently compromised mechanically?

The dropouts are really shallow. I don't think they will even cover the flats of the axle. I know there's not too much material, be you may be able to get the axle to sit a millimeter or two deeper with some light filing/reshaping.

Are you sticking with 29", or maybe building a 69er?

Also, on the other side, you could anchor it using a piece of 1" angle iron, could even be aluminum, cutout to fit around the caliper, and attached by the caliper bolts. You may need an extra washer at the dropout, but then you could use the same Grin torque arm and bolt to it.

 

[Manbeer]

First post so Hi! Lol
Any thought on using one of these as means of a more secure mount to the frame as you are not thrilled with hose clamps? I'm pretty sure that using this on the non-drive side, if you couldn't adapt to the holes it already has that you could pretty easily drill something out that would provide a solid mounting point for you

https://www.google.com/search?q=a2z+disc+brake+adapter&oq=a2z+dis&aqs=chrome.1.69i57j0l3j46.3959j0j4&client=ms-android-verizon&sourceid=chrome-mobile&ie=UTF-8

I'm also not terribly in love with the idea of using them, and although my first build is with a front suspension fork, I have a set of direct mount front derailleur adapters coming with a hinged clamp to try to create a rigid mounting point up front

https://www.jbi.bike/site/product_details.php?part_number=26229

Obviously the diameter here is too large but something similar would also work.

I'm not sure if the above link will load or if you need to have an account. I'm moonlight as a bike mechanic so I'm logged in to their site. I'm not sure if you need to be a reseller to access or not

 

[goatman]

id be afraid of the tire falling off and theres no way i would use regen at all. my marin is like that and i "machined" a block of aluminum with a skilsaw and a drill, then "machined" the axle with a sawzall and could only fit a single speed on the rear. then i could put 2500 watts and regen to it. id get a different frame if i was you.

 

[bonbond]

Thanks for all the replies.

So you guys think something custom-cut like this wouldn't do the job, then running a bolt through the same hole as the derailleur hanger?

I can see it'd stop the wheel falling out at least, and probably stop the dropout from spaying, but as you can see there isn't much on the other side (and from what I'm reading here I should be thinking about two TAs not just one).

I'm got myself into a bit of a spin here, I'm quite attached to this bike and cant justify a new (second hand) bike of comparable quality, I guess my eBike dreams may be on hold for a while...

 

[goatman]

thats pretty much how i have the torque arm on my trike mounted. ive got 5000km on it at 2200 watts with no problems but no regen. if i were to use regen id make it thick enough to tap a set screw for clamping

 

[bonbond]

Thanks, that’s good to know. One have a TA on the one side?

 

[goatman]

no but i have an aluminum hitch plate that i haul a 35lb trailer with that relies on the torque arm screw

https://endless-sphere.com/forums/viewtopic.php?f=6&t=103834#p1520879

 

[E-HP]

Curious, what size chainring does that frame have clearance for?

 

[bonbond]

My Scale 950? Looks like its got a 39t on there at the moment, with little or no room for anything bigger

 

[E-HP]

My Scale 950? Looks like its got a 39t on there at the moment, with little or no room for anything bigger

Thanks. That's the hardest thing to judge when I'm looking for donor frames on Craigslist, unless I can google a picture with the chainrings in place. I see some nice Scott frames once in a while, but shown with smaller chainrings, so I can't tell if they will take a 46T (I have 1mm clearance on my current frame).

 

[bonbond]

No worries, we’ll if you do find a Scott frame and you figure out a decent approach to the TAs let me know!