Skip to main content
000000 000003 000006 000009 000012 000015 000018 000021 000024 000027 000030 000033 000036 000039 000042 000045 000048 000051 000054 000057 000060 000063 000066 000069 000072 000075 000078 000081 000084 000087 000090 000093 000096 000099 000102 000105 000108 000111 000114 000117 000120 000123 000126 000129 000132 000135 000138 000141 000144 000147 000150 000153 000156 000159 000162 000165 000168 000171 000174 000177 000180 000183 000186 000189 000192 000195 000198 000201 000204 000207 000210 000213 000216 000219 000222 000225 000228 000231 000234 000237 000240 000243 000246 000249 000252 000255 000258 000261 000264 000267 000270 000273 000276 000279 000282 000285 000288 000291 000294 000297 000300 000303 000306 000309 000312 000318 000321 000324 000327 000330 000333 000336 000339 000342 000345 000348 000351 000354 000357 000360 000363 000366 000369 000372 000375 000378 000381 000384 000387 000390 000393 000396 000399 000402 000405 000408 000411 000414 000417 000420 000423 000426 000429 000432 000435 000438 000441 000444 000447 000450 000453 000456 000459 000462 000465 000468 000471 000474 000477 000480 000483 000486 000489 000492 000495 000498 000501 000504 000507 000510 000513 000516 000519 000522 000525 000528 000531 000534 000537 000540 000543 000546 000549 000552 000555 000558 000561 000564 000567 000570 000573 000576 000579 000582 000585 000588 000591 000594 000597 000600 000603 000606 000609 000612 000615 000618 000621 000624 000627 000630 000633 000636 000639 000642 000645 000648 000651 000654 000657 000660 000663 000666 000669 000672 000675 000678 000681 000684 000687 000690 000693 000696 000699 000702 000705 000708 000711 000714 000717 000720 000723 000726 000729 000732 000735 000738 000741 000744 000747 000750 000753 000756 000759 000762 000765 000768 000771 000774 000777 000780 000783 000786 000789 000792 000795 000798 000801 000804 000807 000810 000813 000816 000819 000822 000825 000828 000831 000834 000837 000840 000843 000846 000849 000852 000855 000858 000861 000864 000867 000870 000873 000876 000879 000882
English French German Italian Spanish

Wheel Offsets

A review of correspondence from NOC-L

The debate about how Commando wheels are supposed to be centred


Commando wheel offset dimensions

"I sent my wheels out to be rebuilt with stainless steel spokes. The front came back built incorrectly - the rear I'm not sure about. The offset on the front is way off, such that the tyre is contacting the fender bracket. The rear I'm pretty sure is OK, since the tyre is equidistant between the swinging arm - it's not positioned in the middle of the fender, but that might be correct"

Thanks to everyone who responded with measurements of their wheels. While waiting for responses, I was able to find someone who has built a fair number of wheels who gave me copies of his notes about the correct offsets. I also spoke to Ron Fratturelli of British Marketing who gave me quotes from the specs they have there at British Marketing.

It turns out that my rear wheel is within spec. and my front is off by approximately 1/8". The specs are 1/2" from the hub rotor flange to the rim for the front, and 1" to 1-1/16" from the edge of the hub on the cush drive side of the rear wheel to the rim. That puts the rear rim in the centre of the swinging arm.

The fascinating part of this exercise is that several people said their front rims were centred in the middle of their forks (or felt they should be centred). Neither my wheel, nor the specs. have the rim centred in the forks; it has an offset of about 3/16". I don't know if this is a Mk.lll specific offset or if all front disc-braked Commando rims are supposed to be offset.

John S. Morris (jsm@mediaone.net) on NOC-L 4th. Oct 1997


Commando rear wheel offset

I read someplace that the offset that you find in the isolastics is made up at the rear wheel. The hub is laced so that the wheel isn't centred in the swinging arm but set about ¼" to the right.

Bob Patton (bpatton@humboldt1.com) on NOC-L 9th. Oct 1997


Commando rear wheel offset - why should it be that way?

Whereas the offset reported by Bob Patton is likely true, it is still really counter intuitive, and difficult for me to accept. If the rear wheel is centred in the swinging arm, and the swinging arm is centred in the frame, then the front wheel should be as well. Since the steering head by definition is on the frame centre line, then the front wheel should be centred in the forks. Having the front wheel offset to one side makes no sense to me at all.

Greg Kricorissian (grkricor@ccs.carleton.ca) on NOC-L 10th. Oct 1997


Commando rear wheel offset - it shouldn't be

I just checked a Mk.lll that has never had its front wheel tinkered with since leaving the factory and it is centred between the forks. Also all pre-Mk.lll Commandos that I have had re-laced were centred before and after I received them back from Buchanan's Frame Shop.

Gary Slabaugh (gdslabaugh@sprintmail.com) on NOC-L 11th. Oct 1997


The Commando swinging arm is offset

I agree that the front rim should be in the centre. The swinging arm however is not centred in the frame! The frame mounts are centred but the rear isolastic is offset by 3/16". If the arm itself is symmetrical then the rear rim has to be moved over to put it in the centre. I have straightened many Commando frames but not as many swinging arms. Perhaps on the later ones the arms were made with an offset. I do know that the 750s had a symmetrical arm and the rim offset 3/16" to make up for it.

Vernon Fueston (fueston@snowcrest.net) on NOC-L 11th. Nov 1997


Is the Commando front wheel bracket important to the offset?

Do all Commandos also have the bracket (06-6160) between the fender and the slider where the brake line passes by? My bracket is just about the same thickness as the offset of the factory spec for the rim, which centres the fender over the tyre. Or another way to ask - are all fenders offset over the tyre 3/16" because of the bracket?

Today at European Motorcycle Day I took advantage of the Nortons in attendance, in particular the six Mk.lll Commandos which were entered in the show. All looked to have original spokes and wheels. I chatted with three of the owners and all three said that they believed their wheels to be original. Five of the six front wheels had offsets comparable to the Norton spec. One of the six was centred in the middle of the slider. All six had the same bracket holding the brake pipe so that the fender appeared to be centred on the five with offsets. On the one without the offset, the fender looked slightly off-centre.

As much as I respect the engineering logic of having the wheel centred, the fact that the Norton spec., a reputable and experienced Norton wheel builder and a fair number of examples all include an offset for the Mk.lll front wheel, I'm convinced that the offset spec. is correct but that there are some examples on the road which do not conform to the spec. Apparently they don't suffer any ills because of it.

John S. Morris (jsm@mediaone.net) on NOC-L 12th. Oct 1997


Do not confuse Commando hub offset with rim offset

I think there is some confusion between front wheel offset as measured in relation to the hub, with offset as measured in relation to the forks.

The front wheel is supposed to be centred in between the forks of a Commando no matter what year or type of brake (i.e. no offset). On disc braked Nortons the wheel is not supposed to be centred on the hub since the hub flanges are not equidistant from the forks. If the wheel is laced up so it's centred on the hub it will be offset to one side of the forks.

On a disc brake equipped Norton, in order to have the wheel centred between the forks, the wheel must be laced with some offset in relation to the hub centre. The easiest way to do this is to have the wheel builder measure the offset before disassembling the wheel. Experienced wheel builders usually do this as a matter of course but unfortunately some assume the wheel must be centred on the hub.

As far as I know the rear wheel on a Commando should be centred in the swinging arm. I have never measured a Mk.lll wheel but I would guess it is conceivable the rear must be offset on the hub like the front.

Raul Biascoechea(raul-sandy@juno.com) on NOC-L 14th. Oct 1997


Commando engine and rear wheel offsets

"When assembling a Mk.lll Commando recently, I found that the engine/gearbox was indeed about 1/8" offset.

I met a guy with a really beautiful Commando, but it handled like a snake. He had the rear wheel adjusted so it was centred in the swinging arm and when you looked at the adjusters at the axle you could see they were way off, pulled to the right.
"

If you are lucky enough to have wheels that line up, you still have to deal with the offset of the engine/cradle/swinging arm. The load path isn't straight and cants the cradle and frame against each other which is maybe why you can't set them with the wheels on the ground.

Drum brake Commandos, like their Matchless and Featherbed framed predecessors using the same hub, have their rear rims centred on the hub. I am not familiar with the Mk.lll rear wheel - it has a conical hub, no? and uses that same whopping big thick disc caliper as used on the front; the one that requires a huge offset of the front rim for clearance.

On every Commando I have ever seen, the top frame tube runs dead centre down the middle of the cylinder head, and the head steady, symmetrical in design and construction, bolting up neatly as intended. It is true that the main front and rear isolastic spacers and so forth are not symmetrical, but look at any motorcycle and you will find differing left and right spacers on the motor mounts. Engine cases are never symmetrical due to the different requirements for containing timing gear on one side and primary drive on the other, and I suspect the whole mystery has its origins in that fact, although on the Mk.lll Commando the caliper-required wheel offset also influences the situation.

Ben English (ben.english@DMVMS.mailnet.state.ny.us) on NOC-L 14th. Nov 1997


The Commando rear wheel is offset

First of all, Commando drum brake rear rims are not centred on the hub. My notes (stolen from Buchanan's) show the rim centre three and a half inches off the brake drum outer edge (not the backing plate). If you centre the rim on the hub you will miss the frame centre by about ¼". The isolastic mounts are off centre but the swinging arm is not symmetrical either which confuses the issue.

I now have a 1973 850 Commando frame on the table. Fortunately I am also in possesion of cases, cylinder, head, swinging arm, rear wheel and all the related hardware. I will assemble the pieces on my straightening jig and see how they all interface. The Norvil headsteady is definatly not symetrical so I suspect there is an offset to the head.

Vernon Fueston (fueston@snowcrest.net) on NOC-L 15th. Nov 1997


Commando front disc and engine only are offset

All my records show that the rear drum on a Commando is perfectly centred. The front disc is offset, yes, but any non-symmetry at the rear is new to me. I did a wheel perfectly centred last winter without any ill side effects, and yes, the engine is also mounted offset inside the frame.

Klaus Kaak (kaak@inforamp.net) on NOC-L 15th. Nov 1997


Commando wheel offset - the definitive answer

I have the definitive answer as to what is offset, how much, and which way!

I set up a 1973 850 on the frame table and verified it was straight. I then put together a dummy engine and installed it with new isolastics, new washers, Hemmings adjusters, and a Norvil head steady. I put both adjusters on the left side, checked the swinging arm in my fixture and then installed it in the frame. I took all the play out of the adjusters and started measuring:-

  • The frame is symmetrical
  • The engine/gearbox cradle is offset 1/8" to the left.
  • The swinging arm is offset 1/8" to the right so the axle pads end up centred in the frame

I then installed the rear wheel:-

  • The spoke flanges are offset 1/8" to the left as mounted in the arm, so the rim is laced off 1/8" to the right to put the tyre in the centre
  • The centre of the rim is 3.3/8" from a straight edge laid across the brake drum (not the backing plate

With the stock Dunlop rim, if you sight across the rim on the brake drum side you will see about 1/16" of hub when it's in the right place. In my opinion, front and rear adjusters should be on the same side. Otherwise as things wear and you take up the slop you angle the engine and gearbox in the frame. Since the swinging arm mounts to the cradle, a little one way in the front and a bit the other way in the back and the rear wheel is out of line considerably. The chain will still line up but the wheels will not.

Vernon Fueston (fueston@snowcrest.net) on NOC-L 22nd. Nov 1997

 

Norton Owners Club Website by White-Hot Design

Privacy Policy