Author Topic: Let's torque arms....  (Read 11526 times)

Offline MonkeyMagic

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Let's torque arms....
« on: June 28, 2010, 10:00:21 AM »
Howdy

Just took some pics to post in another topic, so I thought I would share them here.

For those who don't trust their bike frame like me, and want some added safety. Here is an easy way to implement a torque arm/plate to your ride. This method is a fitted plate bolted to the rear bike frame axle plate that's welded to your frame, really it's suited for steel frame bikes or bikes that do not have a special rear drop out. Your bike also needs either rear rack mounts, disc brake caliper mounts or if none of the above you need to work out if you can drill bolt holes in the flat area the plate will be [see the pics below to see what I'm talking about]

Why do people do this? Well I've seen in person what an electric wheel can do to a bike rear drop out axle: regardless of quality of the bike frame, the tread on the wheel axle basically acts as blades when immense force is put on the axle dropout. This occurs most applying regen brakes at speed generally down a steep hill, but also can happen at take off or a applying rear brakes heavily; locking up the wheel.

How to:
-Get a thick piece of steel. [Even use a thick shelf bracket, or double up. You want at least 3-4mm. The thicker the better]
-Align the plate onto your frame dropout and mark the angle the wheel axle sits at.
-Using the fitted washer that came with your wheel, trace the inside on your piece of steel where the hole will be
-Drill a 10mm hole in your piece of steel where the axle will fit through
-Here is the patience part... Make sure you don't drink too much beer before this; With a small file, file out the hole to the fitted size of the axle [14mm, so 2mm rounded each side] -- I did this by clamping the washer behind the hole and filing it out just a little smaller than the washer hole> Creating a really tight fit. The tighter the better. Keep checking your plate to fit or jiggle tightly onto your wheel axle. Be patient!
-If you have made left + right plates like I did, label them for your upcoming reference. [Do it on the inside, 'cos I did outside now I want to paint it haha]
-When the plate fits (and you smile), get a small pencil lead or something and mark the holes behind the brake caliper/parcel rack holes
-Drill the bolt holes in your plate(s)
-Bolt up those bad boys and check the plate sits snugly on your frame. Also check you have plenty of beer in the fridge.
-When you are happy, take the plate(s) off and paint them to your bike color.
-When dry, fit them up and find someone to high 5. Then remove the beer from the fridge and consume... Don't drink and ride though!!

Here's the pics. I don't forsee any problem with this method apart from the possibility of completely snapping the weld at the rear drop out on the bike frame... Pretty unlikely... This also looks neater, painting it to your bike color you wouldn't really guess it was there. I grinded my plate to fit the rear dropout area pretty well. This also serves a purpose should the plate somehow shift around it will also have the bike frame to hit on. Anyways I don't see why people are paying $20-$40+ for a piece of steel then fixing using hoseclamps. If you don't have bolt holes fair enough, but I did this in around an hour.
There are however, some good products for front forks you can buy that require hose or similar clamps as drilling hole will destroy the forks strenth. IMO torque arms are a rule of thumb for front forks.

Not criticising anyone! But don't use a hardened wrench or a spanner or anything, then hose clamp it whatever to your frame. Of course there are some that have worked for ages and suit the rider but I've seen in forums when they fail and just aks yourself; how many shifters[spanners] have you snapped using your hands? I've snapped heaps! Maybe keep that in mind.

Pics:


Offline Leslie

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Re: Let's torque arms....
« Reply #1 on: June 29, 2010, 11:42:03 PM »
Solid as a rock Monkey.  :P

I never needed one for a rear wheel.  Even on a thick alloy frame dropouts.

I still use one though.  Just a modded spanner.  

Some ass undid all the bolts on my wife's ride outside the mall one night including the rear hub bolts.  He didnt miss many bolts.  Even undid the handle bars and a brake caliper allen bolt pin was undid almost until it fell out.  :o

Welll she rode it around for a few kms before I gots the mobile call.  "SOMETHING IS WRONG".  Oh my! I dyno brushed out to her ASAP.  The alloy drop out did survive admirably without a torque arm, and she was carting a smallish load in the trailer.

The bars were all wobbly the wheel was rubbing against the frame the brake handle was undone and the front wheel was set to fall off. I thought at first I had forgotten to do one or two things up, I felt terrible at first.. But no way she rode 15 kms before I got the call and she reported the problem only happened after she parked it outside the mall.
« Last Edit: June 29, 2010, 11:56:44 PM by 317537 »

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Offline MonkeyMagic

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Re: Let's torque arms....
« Reply #2 on: July 01, 2010, 05:03:29 AM »
Holey moley !!

Les, well from what I have seen you built 'em tough so that should be peace of mind for you there..

That ass deserves a big kick where the sun don't shine... I hope you run into him one day, just make sure you invent a 'detachable' torque arm spanner so you can use it for dual purpose haha

Glad your wifes ride is okay.. Geez I wish I had a girl who rode an electric bike that's a very attractive quality! You must be proud :)


Offline Leslie

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Re: Let's torque arms....
« Reply #3 on: July 07, 2010, 11:01:48 AM »
Holey moley !!

Les, well from what I have seen you built 'em tough so that should be peace of mind for you there..

That ass deserves a big kick where the sun don't shine... I hope you run into him one day, just make sure you invent a 'detachable' torque arm spanner so you can use it for dual purpose haha

Glad your wifes ride is okay.. Geez I wish I had a girl who rode an electric bike that's a very attractive quality! You must be proud :)




I think we were lucky really.  I think if I was riding that night I would of spun it out.



I think where your torque arm wins the award is that it allows you to do up the wheel nut very tight without the risk of spreading the dropouts, I think where things can go wrong is you can tighten the wheel nut up as tight as it should be but from looking at some axel spins it almost looks like over tight wheel nuts in some cases is a possible factor to the failure. Your torque arm design looks like it covers this well.  
« Last Edit: July 07, 2010, 11:04:39 AM by 317537 »

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Offline MonkeyMagic

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Re: Let's torque arms....
« Reply #4 on: July 07, 2010, 11:21:25 AM »
Hey thanks alot mate

You are most correct. The whole reason I put them on this bike is the rear dropouts were very easy to spread under pressure. As soon as I bolted up the Pie I said nooooo way that is going to hold so I made up the plates the same afternoon.

It really is tough as, I was going to make up 4 plates for inside and out but no way it needs it. I sensed using a rod or bar (arm) of some sort had the possibility of wear over time. Even 1/2 a mm can cause a rattle and I definitely did not want that.

Another note - I might post some pics of my MP rack mod to fit it on/through the frame of a bike. I lined the underside of my battery with felt so there is NO rattle on top of the rack, then modified and bolted the MP seat post rack to my mid frame. Previously having this on the back it is an incredible difference in weight proportion and balance. Plus the bonus you can hug the battery with your knees and lean into a corner like on a motorbike haha

cheers mate

Offline Leslie

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Re: Let's torque arms....
« Reply #5 on: July 07, 2010, 12:29:56 PM »
Hey thanks alot mate

You are most correct. The whole reason I put them on this bike is the rear dropouts were very easy to spread under pressure. As soon as I bolted up the Pie I said nooooo way that is going to hold so I made up the plates the same afternoon.

It really is tough as, I was going to make up 4 plates for inside and out but no way it needs it. I sensed using a rod or bar (arm) of some sort had the possibility of wear over time. Even 1/2 a mm can cause a rattle and I definitely did not want that.

Another note - I might post some pics of my MP rack mod to fit it on/through the frame of a bike. I lined the underside of my battery with felt so there is NO rattle on top of the rack, then modified and bolted the MP seat post rack to my mid frame. Previously having this on the back it is an incredible difference in weight proportion and balance. Plus the bonus you can hug the battery with your knees and lean into a corner like on a motorbike haha

cheers mate

Certainly the 20" and 16" would require a vey good torque arm solution.

I'm thinking of the 700c with about 25 amps continuous.  I only have a few hills.  The advantage of being able to program your current would be cool for the other size wheels too.

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Offline Leslie

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Re: Let's torque arms....
« Reply #6 on: August 11, 2010, 04:29:29 AM »
Interesting post at ES.  Great resource for in that forum.

" In your tests, have you applied any grease to the axle threads? In Bike Mechanic School (UBI), they taught us that greasing the threads can increase the fastening force by up to 40% while reducing friction-based torsional strain." <<<Click to read entire Dropout Failure Experiements, and a call for Fork Donations Thread at ES

Think this info applies here.



« Last Edit: August 11, 2010, 04:31:40 AM by 317537 »

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