Commando-based frame as vintage dirt bike/trail bike

Is the Commando frame and engine cradle up to it? Recently saw a great P11 look-alike based on a Commando frame and it has got me thinking.

I personally don't think a Commando frame is suitable for any off road work other than perhaps a gentle pootle up an unpaved lane. Even with decent off- road suspension I suspect the isolastics wouldn't last long if ridden in the real rough stuff. I've seen some good looking flat-track style street bikes made from Commandos and the S- Type and SS models are sort of 'Supermotard' in style at least. There are one or two dedicated off-road bikes based on P11s on Google images that look really good though.

Even if you could do it, the low end engine torque would dig you into the ground before you went anywhere...unless your thinking some other power plant.

Commando frames bend if you look at them cross.

Wes and I consider the Commando and other B.I. cycles as about best going for both worlds of unpredicable off road hell and predicable Mt. Twisty heaven. I don't like un-linked C-dos to press limits on or off road but their frame is up to it for up to 6 ft high landings I've tried so far. I did a lot of off road on my P!! low slung dragster in deep sand in deep woods with leaps in/out up/over ditches and embankments and pavement humps and slopes catching air time and bottoming out on landing but seemed to take it in stride but my helmet got slammed on bars at times. I have re-enforced Peel's frame to take the crashes on sides and upside down as she's conquerored pavement so so well spanking angery sports bikes no longer interested be but to show off how corner crippled rest of the world is so my real excitement for Peel is severe hill climbs, creek bed runs and the crazy tree stump boulder filled tracks which ain't a scary wild as what I cut my first triple linked Peel's handling teeth on. W/o the full links you may get whip lashed off saddle, so most my wild stuff is done standing on pegs, which low bars don't allow. Do note ya can't do much real off road with street tires d/t lack of grip. If ya stay stuck with the world wide wisdom ruts on how to modify Roadholders your eye teeth will find that's the main weak area in both strength and its limited travel. One of the best practices for real off road fun [as opposed to just scenic beaten paths that is surrounded by raw good stuff > parking lot or grass stunts are a good warm up exercise. My P!! had throttle response to snick through 4 gears w/o brakes and not move a bike lenght out of the smoke cloud but gave fine power control on grass, sand, gravel, leaves sticks and stones as long as dry-ish and same on Peel so the MX and trial bike guys said it was wonderful errie to hear the big twin barks in deep woods among their chain saw sounds. Peel is lifted 2" higher front and rear d/t hi centering on lumps and the sharp edge of ravine drops but does give extra lean angle on the pavement luxury fun. I didn't take many photo's in all the excitement but now we have tiny digital cameras.








Poor things without balls or power response to just leap over the tree stumps sheeze
https://www.youtube.com/watch?v=LEECE2P ... r_embedded

http://www.motorcycleclassics.com/~/med ... s-side.jpg

Like this??

That is pretty wild. Am thinking more vintage style, a la p11 which was a pretty successful dirt bike. The commando SS did not do so well. Frames were similar, just the isolastics were the primary difference I believe.

Look for it on Classic Bikes web site, called the Norvarna I think

I don't know if those stork forks would work out well for road race play but other wise looks pretty temping to me. Tom Davenport mentored me into iso linkages and he lived on a P11 in Calif. with rubber mounted handle bars.

http://www.vintagenet.us/phantom/contents.html



[video]https://www.youtube.com/watch?v=fkYpWySknw8[/video]

Having been involved to some extent in the original Commando design, and heavily involved in its develpment, I wouod advise most stongly against using it for anything except road riding. The frame was specifically designed for the loads expected in street use, and even then we didn't allow for the much higher loads applied to the top tube by front brakes more powerful than the Italian 2LS drum brake originally specified.

Taking a Commando frame out into the boonies as a dirt bike would be a disaster. The frame would break up in less than 50 hours. Definitely an environment it was not designed to cope with.

Thanks.

In terms of frame tubes, how is the p11 frame different? The commando production racer which used a big disk and AP Caliper, is the frame up to the task for that?

I guess my dream of having a isolastic p11 is not about to become a reality.

Not sure that Frank is telling the whole story with Commando frames there - suspension loadings come into it too.
And Nortons have had previous experience with similar steering head flexing/cracking troubles, in earlier frames too.
Featherbed road frames had to have the steering head gussetted to give it sufficient strength.
And earlier Norton lugged frames (ES2, Model 7, etc) had a bit of a history of cracking their tubing around the steering head too.

To be fair, so did a lot of other makes of bikes - remember the GP Triumph that crossed the finish line of the Manx TT with its frame tubes cracked through.
Thats why the all welded (not lugged) frames were such a revolution in frame making.

P11 used lightweight Reynolds 531 frame tubing, all bronze welded.
Well proven frame design from Matchless and Ajay compy bike use.
Very flexible and forgiving, rather than cracking at the first sign of hard use.

Anyone know if AMC welded P11 frames up themselves, or had Reynolds Tubing do the welding.. ?

elefantrider said:

Is the Commando frame and engine cradle up to it? Recently saw a great P11 look-alike based on a Commando frame and it has got me thinking.

Click to expand...

Great trail bike

Nortiboy said:

Great trail bike

Click to expand...

Until you get to some serious mud !!

I used to look in awe at those advert pics of Atlas scramblers, as they were called, before they became N15CS and then P11 etc.
Might be OK in dry sandy conditions, but in serious mud they'd be a real handful.
And your chances of dragging them out to dry land would be somewhat negligible.

Horses for courses... ?

Nortiboy said:

Great trail bike

Click to expand...

Hopefully, its owner has re-routed the rear brake cable :shock: since that photo was taken?

You may recognise the design carry overs as the designers were the same.



and put to use



No iso's but as last time I took my Commando to the Isle of Man I took it green-laning and managed better than a B40WD so I would give it a try.

year , theres a excellent looking M-X tyred Commando Ex Roadster from Sydney , pictures On Here , Somewhere .

If its damp with knobblies , it aint gunna stress . 1000 mph through sage brush and rocks might be a differant story , with the od lauch'n all . :lol:



Aparently they do this in Israel . You can even get the T - Shirts .

still trying to find the yellow 1972 bike picture with the same exhaust . :x

When I was 20 and wanted to blow out static of school, drugs, gangs, draft and war time riots and girls I'd risk broken foot/ankle or knee to start the P!!, but was so so loud [cop bait] and so low in front was impossible to lean to turn even a major city hwy 4 way intersection, [Tallahasse Fla. state Captiol} so was also impossible to road race on hilly curved hwys, unless in city by stunt bike parking lot, drag wet tire heat smoke out leaps and slides or flat tracker crossed up hi speed slides over 60, which is fine for shows but not public traffic hazards... No problem to drive it anywhere as long as like a bagger with floor board foot forward style. It was so quick in lower gears I'd use mere road crown to catch air leaving stop lights [it did not wheelie just smoke or leap, like that daul engine Triumpet smoking rear standing on tail, P!! would only wheelie to level doing that, ie: floating front 2" high, each gear and half way in 4th] so if an elevated hwy side ramp approach could clear 4 ft across 4 lanes twisting forks side to side and waving at drop jawed wide eye'd folks in stopped cars either side to land on down slope almost bottoming then hit torque on the extra tire patch area to leap out of there, flinging the flying fickle finger of fate into Creators face testing the states of being acid and mushrooms in the spirit of the times with LBJ's lottery number ticking closer. So would head out to the woods and quarries, logging cuts and sink hole swimming hang outs. Ya don't need no long ass fork or much frame clearance if power and traction enough to just lift the front over about anything with enough momentum to bash though sod and limbs, as long as keeping the spun in air rear powered up so ya don't land on nose. On return home next to empty lot with nice grass ditch off road grade and steep 6-8ft tall embankment into lot, I'd slow till could nail rear around to leap dead on into this for the Zero G till bottoming then the several G's launching out then the peace full flight time many bike lengths to land securely w/o hitting helmet on bars then kettle drum idle thump back down and into echoing garage. Don't think the Norton desert racers had much frame issues either.

If Frank was right about the isolastic Commandos then Wes and I would of broken down a few each by now. We break spokes and shock rubbers and rear loops and tail light mounts and battery tie downs and signals and tire surfaces plus ignore torque values on most fasteners but doggone frame and stem taking it in stride. We get surprised by hidden lumps or wash out ruts that bottom-compress everything so solid the jar hits sacrum into chest out jaw and skull pushing a grunt sound out. Hope to make my own trails and stunt course for Peel when the taboo side car is on or off. The scope of a Commando doing stuff well is immense to me and my tool of choice bar none.