XF08 in narrow dropouts - advice needed

[Woosh]

You can do one of those things to put your mind at rest but you don't have to. For all the years that I've been selling hub kits, I only put torque arms on heavy motors like the Bafang BPM kits because of their high inertia and on the Gran Camino because it is meant for trail riding.
Your XF08C does not weigh anything like enough for inertia to be a problem.
As for deepening the rear dropout, it's good to do that for your peace of mind but again, you don't have to. As long as you ride on made roads, your weight on the rear wheel is enough.

 

[Nealh]

Just add the torque arm with no filing , easy to do and easy to return to a std push bike with undamaged drop outs.

 

[saneagle]

All this talk of axles spinning out is making me sweat.
So I've ordered one of these:

Are you sure that's not 14mmx 10mm instead 0f 12x10?

 

[Waspy]

Are you sure that's not 14mmx 10mm instead 0f 12x10?

Perhaps they used the same picture for both sizes.

 

[saneagle]

Perhaps they used the same picture for both sizes.

OK. I was worried because Hammer bikes do mainly DD motors. Sorry to worry you. Better safe than sorry.

 

[Waspy]

OK. I was worried because Hammer bikes do mainly DD motors. Sorry to worry you. Better safe than sorry.

Thanks for having my back, bro. The one I ordered is 5mm thick and meant for DD motors. They do a 3mm one for 250w motors, but those don't have the adjustable arm angle, which I really fancy. I'll let you know how I get on with it.

 

[Dadam]

Ordered and fitted 5mm torque arm, the same one as @Waspy, better safe than sorry. Didn't want to file the dropouts deeper as it would be getting close to the fixing bolts for the derailleur hanger, and potentially weakening them.

I wanted to fit it drive side as I thought it would be neater, more or less hidden by the rear mech, and there's more meat on the threaded axle. But it just wouldn't fit; no room with the derailleur mount there, so here it is on non drive side. Only 2 threads showing inside the nut so plenty of thread still engaged.

 

[Nealh]

It's a shame hub makers don't make the axles a bit longer ( 12 -14 mm) esp on the LHS , one then could also thread on or fit a tralier hitch better . One has to be careful when only part of the thread /nut is tightened , it is possble to strip the thread in time.

As it has the inner adjustable ring , I would have dispensed with the bolted second section/arm and tried to use it as a one piece Torque arm, If the arm sat flat I would drill a hole in the first /main part to align with tapped hole.

 

[saneagle]

Ordered and fitted 5mm torque arm, the same one as @Waspy, better safe than sorry. Didn't want to file the dropouts deeper as it would be getting close to the fixing bolts for the derailleur hanger, and potentially weakening them.

I wanted to fit it drive side as I thought it would be neater, more or less hidden by the rear mech, and there's more meat on the threaded axle. But it just wouldn't fit; no room with the derailleur mount there, so here it is on non drive side. Only 2 threads showing inside the nut so plenty of thread still engaged.

You can sling the anti-rotation washer on that side. It's not doing anything to stop the wheel rotating. that will allow you to get the nut on properly, which is much more important.

 

[Dadam]

You can sling the anti-rotation washer on that side. It's not doing anything to stop the wheel rotating. that will allow you to get the nut on properly, which is much more important.

Problem is as I mentioned upthread I needed it on the inside to align the disc in the caliper. The photo angle makes the nut engagement look worse.

 

[Dadam]

Managed to find my verniers and nipped out to the garage. The end of the axle is 3.4mm inside the edge of the nut, however the inner bevelled surface is roughly 1.7mm deep so the actual amount of missing thread engagement is only 1.7mm, and there's a good 9mm engaged.

 

[saneagle]

You can sling the anti-rotation washer on that side. It's not doing anything to stop the wheel rotating. that will allow you to get the nut on properly, which is much more important.

Normally, a single 12mm washer on the inside of the drop-out gives the correct disc alignment. The anti-rotation washer is about 2.5mm thick, so your disc must be right at the end of the slot instead of the middle.

 

[Dadam]

12mm? Did you mean 2mm thick (typo), or 12mm ID? If you look at the OP, that was with the supplied 2mm washer (might be 2.5, can't easily measure without taking it out) inside the dropout and the AR washer outside. That configuration put the caliper too close to the disc (in fact the disc itself rubbed on the chainstay). With just the AR washer inside (post #8) it was near spot on, close to the centre of adjustment range.

Right now the supplied 2mm washer is between the dropout and the torque arm, but that is currently needed or I'd need a chunky spacer between the main torque arm and its adjustable arm, as the hole it's bolted into stands proud of the dropout flat by a fair bit. Already got an extra washer in there.

 

[saneagle]

12mm? Did you mean 2mm thick (typo), or 12mm ID? If you look at the OP, that was with the supplied 2mm washer (might be 2.5, can't easily measure without taking it out) inside the dropout and the AR washer outside. That configuration put the caliper too close to the disc (in fact the disc itself rubbed on the chainstay). With just the AR washer inside (post #8) it was near spot on, close to the centre of adjustment range.

Right now the supplied 2mm washer is between the dropout and the torque arm, but that is currently needed or I'd need a chunky spacer between the main torque arm and its adjustable arm, as the hole it's bolted into stands proud of the dropout flat by a fair bit. Already got an extra washer in there.

Standard 12mm I/D washer with 24mm O/D. Mine are 1.8mm thick. An anti-rotation washer is 6.25mm thick, so you gain 4.45mm for the nut.

 

[Dadam]

Thanks for the clarification. As I say though, that doesn’t seem to fit with this motor in this frame/these brake mounts.

It’s a bit annoying that the compatibility of this combo seems marginal. It’s a Giant Escape, a road oriented hybrid, so nothing weird or obscure.
But apart from the nut engagement, I’d say things are now pretty close. Wheel fits in now, torque arm for peace of mind. Gear shifting is good, brake alignment is good. Still need to true the wheel but it’s not miles out. At least it’s pretty central now which was a concern the other week.

 

[Woosh]

It's a lot of faffing for no real benefit. Millions of those rear hub kits have been installed without torque arms. Have you ever heard that their wheel comes off on normal road?

 

[saneagle]

It's a lot of faffing for no real benefit. Millions of those rear hub kits have been installed without torque arms. Have you ever heard that their wheel comes off on normal road?

You're right that you don't really need a torque arm with a properly installed rear motor withh relatively low power, but OP's axle is not properly in the drop-outs. I wouldn't ride a bike like that without a torque arm. It's not the same as an OEM bike that has a properly fitting axle.

I've seen two front motors pop right in front of me. One had a relatively high torque motor,that the owner was testing it up and down the road, when the motor popped out at low speed and dumped him on the ground. The other was a normal sized motor in quite thin forks that dropped when the bike was pulling away from a stop. The wheel went, but the bike didn't.

 

[Waspy]

I have one of those torque arms waiting to be fitted but I am away at the moment so it will have to wait. I can forsee similar problems, mostly because the axle is a bit short on the brake side. I can see a lot of jiggery-pokery with washers etc. The torque arm seller had 3mm thick 12x10 torque arms but without the adjustable angle, which I wanted. As Woosh says probably totally unecessary (for me) but I do like a bit of fiddling (has to be a dry day mind as I have to work on my bike outside). I wonder if a slimmer M12 axle nut may solve the short axle issue?

 

[Dadam]

It's a lot of faffing for no real benefit. Millions of those rear hub kits have been installed without torque arms. Have you ever heard that their wheel comes off on normal road?

I hear you, but it would have niggled me, with the lugs of the anti rotation washers not fully inside the dropouts. For the sake of 15 quid it was a no brainer. It's fitted now and all seems solid.

Out of interest do you get many customers' bikes with shallow dropouts like mine?

 

[Woosh]

Out of interest do you get many customers' bikes with shallow dropouts like mine?

Yes, we do.
When I convert a bike with shallow dropouts, I have a very good a 10mm round file. I spend 5 minutes deepening the dropouts.
The risk with shallow dropouts is not as big with a rear hub compared to a front hub. The rear of the bike does not bounce as much as the front. You also put 75% of your weight on the rear hub.