rear frame loop strength

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toppy

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How strong is the rear seat loop of a Commando frame?? I am planning on fitting a small carrying rack to my 74 roadster to carry a chain (the chain it to lamp post to stop someone stealing it kind) but hope to go away for long weekends touring with friends. This will not involve camping gear just small rucksack or at the most throw over saddle bags. I have heard the rear loop may bend if over loaded but as I ride solo an luggage will weigh less than a pillion passenger should I worry about adding bracing to the rack to share the load between it an pillion footrests
 
I had a Craven rack on my MK3 and carried all sorts of stuff on it no problems, but I was a lot younger then and didn't know I was riding a 'classic'. If you get a purpose made rack and don't put on too much weight, it should be fine.

CB
 
rear loop is strong enough to ride with 2 adults . The MKIII is stronger thanks to longer bracing .

Anyway up you intend to fit a carrying rack it's better to have some tubing going down to the passenger footrest.

This is a hepco rack and luggage system sold by Andover Norton . You can see the support on rear footrest on this picture
rear frame loop strength
 
JRD said:
rear loop is strong enough to ride with 2 adults . The MKIII is stronger thanks to longer bracing .

Anyway up you intend to fit a carrying rack it's better to have some tubing going down to the passenger footrest.

This is a hepco rack and luggage system sold by Andover Norton . You can see the support on rear footrest on this picture
rear frame loop strength
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Mine sagged. I suspect it was from two up riding and the passenger carrying a case of beer and two porter house.
 
The rear loop does not carry much of the weight of a pillion passenger. That weight is distributed through the seat pan to the top shock mounts with a lesser amount on the rubber bumpers resting on the rear fender. That fender is mounted at the bottom of the frame and the frame loop, spreading out that load. It does not take much weight to make that loop bend and touring with 20-25 lbs on it can make it sag over time. I would not use a luggage rack that doesn't at least brace at the top shock mount and clamp to the loop. For touring I would only use one that triangulates to the passenger pegs.
 
you are just fine, no worries

I travelled fully loaded on the rear with all my camping stuff for over 4000 miles in two weeks crossing the USA
 
1up3down said:
you are just fine, no worries

I travelled fully loaded on the rear with all my camping stuff for over 4000 miles in two weeks crossing the USA
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On the seat or on a non-triangulated luggage rack clamped to the rear loop?
 
I agree from testing to point of loop failure after some creeping up sagging, that 20-25 lb is about tops for routine loads over road bumps. Pre-Peel failed with some groceries and couple oil quarts and a skill saw in a milk crate bungee'd on a luggage rack w/o the support struts. With struts on the heaviest thing carried was a 33" mudder PU truck tire/wheel to a shop, over miles of THE Gravel roughness ok. Main issue of struts is to space out off loop enough there's a straight shot at the Z plate w/o fouling the shock springs.

rear frame loop strength
 
Main issue of struts is to space out off loop enough there's a straight shot at the Z plate w/o fouling the shock springs.
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The Craven system uses flat strap steel that curves around the shock spring.
 
swooshdave said:
cmessenk said:
swooshdave said:
:mrgreen:
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Our bikes weren't made for flipping and landing on their asses, Dave, without some visible effects.
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You're no fun!
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Just stating the facts...I know what that bent tube means...not the result of fat-assed pillion...don't ask me how I know this. :roll:




BTW, I still have the scars to prove it.
 
Put Peel upside down 4 times so attest that is not how rear loop get bent but sure can the handle bars and swing arm. Hauling a heavy pillion will bottom the shocks or tire on the fender but loop is out of that load loop.
 
Ron L said:
The Craven system uses flat strap steel that curves around the shock spring.
Click to expand...

That sounds like material just waiting to curve some more, under stress...
 
One of our forum members built this. Looks easy enough with the materials and a welder. I need to get his name to credit him.

rear frame loop strength


Dave
69S
 
At the INOA Rally in Ivy Lea Canada a few years back, 2001 I guess, there was a Canadian Norton rider that had a trailer attached to the rear loop seat frame. He had drilled holes in it and just bolted the trailer hitch to it. He claimed that he has ridden all over Canada 2 up with the rig.
Sorry, no photos, that was way before digital photos. Someone in the Ontario Norton Owners may know of him. Contact Pete Turner from Ontario Norton Owners, ( just catch him before the cocktail hour!!! Ha! )

MF
 
I carry two cases of beer on Trixie's un supported loop and camping gear for two a 1000 miles a trip w/o any sag so far. I try to avoid big bumps at speed though. Poor past Peel's repair, - sliced off the other unfractured bent down side, drilled 3/8" holes in the loop tube end, ground 2 ~ 6" long steel rods to hammer in frame end fully then bammed the loop on to them then welded up then ground back then painted. Then years later I cut up a carpenter square to weld long gussets to weld under ~1/2 the length of the loop. Peel can carry a decent passenger or 4 cases of beer w/o struts over failry good surfaces w/o worry. After Peel's repair I noticed loop was kind droppy yet, so picked up raw frame and slammed the loop on carpet floor til loop leveled up. Its does urk me a bit that there's a few extra oz's of mass I can't remove from Peel now, so wished I'd put in hollow tube instead of solid pins. Peel has special needs and one of those needs its for her rear loop to hold most the bike and pilot mass pressing from below upward with wheelie level engine force adding on to that.

I've never seen a Cdo with a trailer, so interesting report of one with hitch mounted to factory loop. There are no that much downward loads on a motorcycle trailer tongue though. I'm not figured out how to put a hitch on Peel yet.
 
DogT said:
One of our forum members built this. Looks easy enough with the materials and a welder. I need to get his name to credit him.

rear frame loop strength


Dave
69S
Click to expand...

I remember that one. The most elegant design in the history of Norton Commandos. Removes with no tools. Supports the weight perfectly. Fucking brilliant.
 
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