Shimano axle thread

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MarySkater
Posts: 104
Joined: 7 Mar 2007, 2:17pm
Location: SW Scotland

Shimano axle thread

Post by MarySkater »

Please can someone help a non-technical person...

I have a new bike. I have an old, but serviceable, Burley cargo trailer. My trailer did have the old style of Burley hitch ("Classic") which clamps on to the rear triangle (is that the right phrase?). But that won't work on the new bike which has the nearside chainstay modified to take a prop stand (which I want to keep). The Classic hitch doesn't fit.

So I need to change to the new, "Standard" Burley hitch, which fits on to the rear axle, to be left permanently on the bike. Okay so far, I can manage to use a spanner. However, the hitch does interfere with folding the prop stand. It's possible, but not ideal. Burley offer hitch adapters, a small stand-off which screws on to the axle. The hitch then fits on to the adapter, and is thus moved slightly further out from the bike frame. I think this might make it easier for me to position the hitch, and I'm willing to give it a try.

Now comes my problem: Burley offer variations of this adapter, according to the diameter and thread pattern of the rear axle. The options are:
3/8 x 26
M10 x 1.0
M10.5 x 1.0
QR

I assume QR is quick release, which I don't have, so I can eliminate that. But which of the others is right? I have a Shimano Nexus 8-speed hub gear. I've tried looking up Shimano specs, and they give the axle length but not the thread. The bike is a Riese & Muller "Blue Label" pedelec, but the bike manual also doesn't mention the axle thread. Can anyone please tell me what thread I have?

Mary
I used to be known as "maryinoxford," but I've moved...
MartinC
Posts: 2127
Joined: 10 May 2007, 6:31pm
Location: Bredon

Re: Shimano axle thread

Post by MartinC »

I have a recollection (I can't check at the moment 'cos I'm away from home) that a Nexus axle is 9.5mm.
Brucey
Posts: 44522
Joined: 4 Jan 2012, 6:25pm

Re: Shimano axle thread

Post by Brucey »

IIRC the correct size is 3/8" x 26 tpi.

You can verify the pitch by offering up a screw alongside (like a thread pitch gauge) that is also 26tpi or at least eliminate 1mm pitch using a 1mm pitch screw.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~
MarySkater
Posts: 104
Joined: 7 Mar 2007, 2:17pm
Location: SW Scotland

Re: Shimano axle thread

Post by MarySkater »

Thanks for the input. Sorry, Brucey, I can't do your suggested test, because I don't own any screws of known pitch...

Maybe I need to think again about the problem. The standard hitch:
Image
hangs vertically from the axle. In that position, it only allows the prop stand to fold halfway up. It would probably be okay, but it sticks out a bit and could conceivably catch on something. When not using the trailer, I could slacken the nut and swing the hitch 90 degrees to the right, so it's "trailing." In that position, it's fine, not in the way at all. But it means adjusting the hitch whenever I use the trailer (maybe once or twice a month). I'm a bit worried about wear and tear on the nut and axle if I go that route. If I do, I think I need to invest in a torque wrench to be sure I'm tightening the nut enough but not too much. Any recommendations for a tool for the job?

Mary
I used to be known as "maryinoxford," but I've moved...
Brucey
Posts: 44522
Joined: 4 Jan 2012, 6:25pm

Re: Shimano axle thread

Post by Brucey »

if you have a standard M6 screw that will have a 1mm pitch. If you don't have one on your bike somewhere you can buy such a screw for pennies. I am reasonably sure about the size of the thread BTW.

I think you are right to be concerned about the wear on the axle and the nut if you are planning to loosen it regularly. The ends of Nexus axles are not super-hard or anything.

I think the Burley tow hitch bracket design is flawed in that the thrust loads from the trailer are alternately trying to turn the bracket one way or the other. In this respect the (say) Carry Freedom bracket and lollypop arrangement is a better idea; the thrusts are all in one plane.

Thought; is there any reason why you can't mount the standard Burley bracket the other way up, and leave it be?

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~
MarySkater
Posts: 104
Joined: 7 Mar 2007, 2:17pm
Location: SW Scotland

Re: Shimano axle thread

Post by MarySkater »

Brucey wrote:Thought; is there any reason why you can't mount the standard Burley bracket the other way up, and leave it be?


That's an option I'm seriously considering. At the moment it won't work because the fittings for rack and mudguard get in the way. That's why I wanted the adapter, to push the hitch a little further out and then put it on upside down and leave it. It would make the attachment a little higher than it's meant to be, tilting the trailer slightly up at the front. But I don't think that's a serious problem so long as I'm careful when loading anything heavy (i.e. keep it in front of the trailer axle, so that the weight is pressing the bike wheel down and not lifting it up.

I suppose I need to get hold of something that will let me confirm the shimano thread.

Thanks, Brucey.

Mary
I used to be known as "maryinoxford," but I've moved...
Brucey
Posts: 44522
Joined: 4 Jan 2012, 6:25pm

Re: Shimano axle thread

Post by Brucey »

here;

http://www.sjscycles.co.uk/shimano-nexus-br-im40-cap-nut-3-8-inch-prod23812/

there is a listing for all the hubs that use the same 3/8" nuts. Sheldon Brown identifies the threading as 3/8" x 26tpi too.

cheers
-------------------------------------------------------------------------------
~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~
MarySkater
Posts: 104
Joined: 7 Mar 2007, 2:17pm
Location: SW Scotland

Re: Shimano axle thread

Post by MarySkater »

Thanks for getting me that info, Brucey. Obviously I wasn't looking in the right places.

Much obliged for your help.

Mary
I used to be known as "maryinoxford," but I've moved...
MartinC
Posts: 2127
Joined: 10 May 2007, 6:31pm
Location: Bredon

Re: Shimano axle thread

Post by MartinC »

Brucey wrote:IIRC the correct size is 3/8" x 26 tpi......................


Nice one. As ever a fount of info. My recollection was from playing around with NTWs to see if I could mix and match them for a Spectro 7. Shimano ones had an internal diameter of 9.5mm, SRAM in 10mm and old SRAM ones 10.5mm (9/32" ?). Can't remember what SA ones were. Some of this could easily go in the other metric/imperial thread!
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