Race Commando handling secrets revealed

Not everyone wants to reveal their secrets especially in racing and I am not retiring from racing yet, although I fell off a few times in 2009 and lost to Kenny for the first time ( I should have retired right there ), I have slowed a bit.
It is possible that there is a better set up Commando chassis that turns in as quick, can be laid on it's side through an 90mph sweeper without a weave and is dead straight at 130mph. Anything is possible.
There is no credit for me, Herb Becker was the brainchild who built the bike, the ideas and fabrication were all his- I was amazed at the difference between this and my original flexi-flyer Commando racebike that weaved and bounced its way all over the track when you started to push hard.
I have raced against Seeley framed bikes, I don't think they have much if anything at all over this bike and mine doesn't buzz your hands to sleep like a solid mounted Seeley.
I am not going to get into shocks or steering dampers, just the chassis set up of the bike.

The modifications;
Looking at the side profile of the bike, you can see that the tank is a custom, shortened version of a Production racer- this allows you to get further forward and get your weight over the front wheel- the seat has been lengthened to compensate. Getting weight over the front is a good thing..


The bike has adjustable front fork rake- stock, 1 degree and 2 degree steeper. I always use the 2 degree steeper. The rake is changed using 2 eccentric machined aluminum inserts that go top and bottom where your normal head bearings would go. Then a smaller bearing is put in there. The maximum you can change the rake with inserts is 2 degrees, after that you are out of room. In the picture, you can see the insert- fat at the back and skinny at the front- the bottom insert will be the opposite.


To make the steeper rake work correctly, you need to use reduced offset triple trees to obtain good 'trail' numbers. Modern sport bikes have very reduced offset triple trees. The bike will now turn in very quickly to the corner.


A good headsteady is a good thing, Herb designed his own which works well but a good aftermarket one should do you fine.


A little frame bracing at the front is a good idea, to stop flexing.


The most important modification, in my opinion;
Early Commando frames have a cross tube under the transmission cradle- Herb used that tube at first to attach his cradle stabilizer block to, but on this frame the tube was added.
To this tube a machined aluminum block was clamped that extends up inside the cradle; a square of teflon extends slightly out from the block on both sides and this is cut to be tight to the cradle.
Now the cradle can only move front to back and not side to side at all. The buzz at the bars feels like a stock Norton to me.



The bike has 5 position adjustable rear shock height- quite simply there are 5 sets of 4 plates that bolt the shock bottom to the swingarm with a 1/4" height difference between each set. I use the the second lowest.


The most tricky bit of the bike is the adjustable swingarm pivot height. The swingarm pivot point behind the transmission can be adjusted to 4 different heights. You will see on modern bikes that the swingarm pivot point is very high- this is beneficial for bike squatting under acceleration and makes for better geometry for putting the power down. There is a plate welded to the back of the tranny cradle and there is an 'H' shaped piece that bolts the pivot point to the plate- this can be turned upside down giving another height and there is another 'H' shaped clamp that gives you 2 more heights. Optimum height is a bit higher than stock.


That is all necessary so you can then go out and do this-


Heat race at Mosport last year, going OK;
[video]http://www.youtube.com/watch?v=_Mg0cqNQeMg[/video]

I think the best video for handling is to watch my on board from tight, twisty Roebling Road where I was still hard on the gas- you can see how the bike transitions quickly from vertical to full lean and is solid coming through the 80 mph sweeper onto the front straight-
[video]http://www.youtube.com/watch?v=EuYrHKk9STA[/video]

That's it. It also helps to twist the rubber thing on the right handlebar toward you.

Thanks to Herb Becker and Walridge Motors.

Very nifty.

That rear block does the same thing as the third links some have done and the idea I believe is one of the best to triangulate the rod joints (or in this case, blocks) with the three isolastics for a fully limited isolastic machine.

Hoot, hoot.

thanx.

awesome

Ohh man, Hobot is going to have a field day with this post. I'm going to make some popcorn!

Doug MacRae said:

....and lost to Kenny for the first time ( I should have retired right there ), I have slowed a bit.

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Well well, my main man Dougie. Yes, you may have slowed, while others have sped up. It's all part of the natural evolution of things.

Doug MacRae said:

I have raced against Seeley framed bikes, I don't think they have much if anything at all over this bike and mine doesn't buzz your hands to sleep like a solid mounted Seeley.

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Hmmm, when was the last time you raced on a Seeley? In fact, when was the last time you raced one with JS Motorsports pistons and a decent balance factor? When???? I thought so.

I smell the gauntlet being tossed here. C'mon Dougie... step up. Any time, any where.

Don't let your little fender-bender at Daytona be your excuse now.

Signed,

Your friend, Holmeslice
#1

Great Post, could you give rake and trail figures for the -2deg setup? Or even just the offset?
Great simplicity to the engine mounts,
I have worked on a commando where we rotated the cradle into the engine, also raising the swingarm pivot.

bwolfie said:

Ohh man, Hobot is going to have a field day with this post. I'm going to make some popcorn!

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He's probably curled in a fetal position now after reading the post. :mrgreen:

Great post, Doug. I love to see all that technical info. Herb really deserves some serious credit for all the work he put into Commando racers for so many years.

Ken

Did that start as a 750 or 850 frame? The manual I have shows the 750 with a steeper head by a degree over the 850 to start with

Curled up like in my mommies womb.

Cleaver as hell modifications especially the fork angle and swing arm height effects on top of the new way to tame the isolastic sloppiness.

Rear camera angle most informative to me to see Doug hanging off and even the tire grind slide at some points.

Front view gives the lean angle meter of horizon, I read as up 55' at most.

Throttle power sounds also informative of pilot trust to stick going into apexes.

Hope Kenny and Doug get to shoot it out some more and live to brag and bitch about it.

hobot can't hang off linked isolastic Cdo as no room nor time to do so while throttling up into crash states w/o a hint of buzz so curling up into fetus now...

Very cool post! What a bike!!! Thanks for sharing and all the detail shots. Superb!

Do you use a rear chain tensioner?

Fork angle looks pretty close to the 24 degree's used on most modern bikes, as does the reduced fork offset. The facility to adjust rear suspension squat geometry looks very useful, and these mods in conjunction with reducing the amount of flex in the isolastic system, are going to improve handling enormously.

However a bike modified in this way will be lot more twitchy than a stock bike with chopper geometry, and may not be ideal for everyone.

Carbonfibre said:

Fork angle looks pretty close to the 24 degree's used on most modern bikes, as does the reduced fork offset. The facility to adjust rear suspension squat geometry looks very useful, and these mods in conjunction with reducing the amount of flex in the isolastic system, are going to improve handling enormously.

However a bike modified in this way will be lot more twitchy than a stock bike with chopper geometry, and may not be ideal for everyone.

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Nope, not ideal for everyone.

Heck, for that matter, Nortons aren't ideal for everyone.

I'm glad we're all not alike or this would be one boring world (unless everyone was like me).

You know I'm just razzing you Kenny. I have told you before we should swap bikes at the track and you will want to park that thing.
Seeleys are for sissies.
I might be in NYC next month, I will let you know

My friend Fred Eiker raced a "wobbley" commando with stock pistons. So he got rid of the isolastics, added a swingarm brace and it handled better but then the frame cracked at the front motor mounts which then needed rewelding & gussets.

To win you must lighten your bike. The isolastics weigh a ton. The CDO swingarm and engine plates are also very heavy at around 24 lbs. If you could lose some of that weight and use the low vibe lightweight pistons/longer rods you should have the best of both worlds (and no one needs to tell you the importance of reliable rods).

Everyone - note the length of his intake manifolds in the first photo (hint hint).

Jim S

Get your pop corn and stiff drinks ready...


Before radius rods ruled my chopper-ish Commando, friction pads were experimented with. Got a teflon pad head steady if anyone cares to play with it further. It has witness marks that show about half the engine bounce arc than the front. Gerry Bristow, aortic aneurysm dead now, made/tested it but felt buzz transmitted so donated it to me. Gerry is the only other rider I know of that practiced flinging both tires off surface in cresting turns to twist in air on CoG to land just right for the hi side upright into full power new direction!
He played his Cdo flings in Greece.

Norton cradle is a bit flexy in each of its rear extensions beyond the iso mount. I tied Peel's rear cradle together so both cradle sides resist the side loading. I assume the swing arm H piece does similar in Herb Becker's ingenious innovations.

Peel's rear frame bottom bends are also tube tied together as each alone is deflect -able by hard hand loading. Bob Patten calculated 300+ lb ballpark of possible side loads to resist by a link attached to that area. I now believe that only applies to phase 2 normal cornering but spikes to over rider+bike mass in Peel flings. I have to resist tunnel vision and brain black out by fighter pilot breath control when I let Peels hair out going too fast to fear what awaits in blinds. This is the only effort I must expend other than throttle working, so no need of athletic conditioning to take Peel around like she likes too. Its a set up us old frail farts can enjoy while thumbing nose at crazy antics elites endure.

I see how yoose real racers hang off and shift around to feel secure, I can't get away with that on Peel in chicane switch backs as each opposite fling would leave me going one way and bike the other. Peel switches direction as fast as one half cycle of tank slapper onset - so no time for pilot to shift one iota. I now feel that tank slap onset is bike telling ya too leaned over and forks too turned out to handle the counter steering which aims front the opposite way bike needs to go. Peel is totally immune to tank slapper onset and self corrects in 1/2 cycle - so no need of stinking sluggish fun limiting steering damper.

I can't get away with hanging off in long leaned over sweepers neither as at Peel rates she tends to fall over all by herself till must straight steer suddenly or low side right down. I find Ms Peel able to handle rather more lean/counter steer than elite modern bikes, so much so I find this steady state power-lean is the most unstable oscillation building state a bike can get into - short of **trail braking into apexes** - an Absolute NO NO to me on Ms Peel or any bike. To enter phase 3 straight steering requires harsh powering up well before max lean at apex relief point - the rest of the world must wait for to put down accelerating power. Hehe too little too late to take on Ms Peel and me.

Once Peel leaves rest of the counter-steering world behind, long held sweepers become a series of short straights - punctuated by severe G spikes of maxim turn angle snatches when hook up is lost on purpose, to get upright to get power hooked better accelerating into next snatch out. So far only had Combat power enough to pull this off up to 90 mph. At Peels rates only increasing excess power controls safe direction changing and resists crashing.
When she runs out of tire spin power she must transition back into normal world of phase 2 steering - which as I said is still too fast to worry about any modern corner cripples to catch up.

Motorcycles of all types are best at taking short sharp max angle loads not long held steady-ish turning. I learned this on fat tired moderns but they then jiggle and shake and tank slap like crazy, -too much for me to predict their sploshing and splashing together of resonances to enjoy, so gave up on em. Even so I pushed them harder to find a way beyond their upsetting limits by hi siding them far and long enough they settled down by time of landing. BUT because their resonance splashing to road texture and wind gusts on chassis is so unpredictable, its risky to launch them perfectly each time, as they may cause slight delay in lift off or lift off before intened, which means then land at slightly unpredictable angles and distances, I gave up on em. Ms Peel loves to do these exactly as I desire right now perfect no matter the wind or road texture.
Side ways air time is phase 4 handling. I only seen Rossi do this once after wining a race and celebrating by crossing up in a straight then jerking straight steer to hi side a tiny bit to get back in line and power away straight ahead.
Even he seems smart enough not to attempt that in severe cornering states on such sloppy corner cripples. I posted the video in other section. Pashaw.

Seeleys are for sissies.

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No way do I believe that Doug, as impressed no end how Kenny and others handle such rigid buzz bombs but then again I don't see you handling Herb's isolastic Cdo any better in posture, leans or throttling up. So nothing for it but two world class experts switch rides on same day and track to see which saves the most time around. Much as i like watching racing on normal bikes its counter productive study to me on Ms Peel. OH how I've tried to practice Peel's lines on my SV650 on 17" non-DOT heated race rubber but no way can it approach the rates-loads Peel must - to be able to use her lines around, so gave up on that forever more. What i would love is let you two have your way with my favorite love and let us know if ya can't get enough of her either to spoil ya forever more.

"Nope, not ideal for everyone.

Heck, for that matter, Nortons aren't ideal for everyone.

I'm glad we're all not alike or this would be one boring world (unless everyone was like me)"

Point here is that when Norton themselves made slight alterations to the Commando steering geometry, several less experienced riders crashed the bikes, so while a bike with modernised handling will suit most people just fine, it might not be good for everyone.

Nay so dear Carbono, my Ms Peel is both the easiest bike to operate in normal legal ways and gets easier yet into 3 more phases of handling than elite racers will do to save a race that makes or breaks their career. Only 125's-250's might be better off road d/t easier to fling and pick up by weaker-smaller women and boys.

I'm so besides myself to get Peel going again as there really is nothing to compare to out there - so its unbelievable to read my posts or even relate to the wonders of a totally Neutral Light handling cycle. I even got a way now to make a hi CR 920 hand lever start-able so even that will not be an excuse for women or boys not to crave one themselves.

I've interviewed Kenny in race pits and others to find their too low slung rides actually pogo on pegs to lift tires in leans so he must shove back up on knee slider. Can't make bike too low I found in both my dragster and moderns to prevent lean enough to make it sharp enough w/o backing off.

Carbonfibre said:

"Nope, not ideal for everyone.

Heck, for that matter, Nortons aren't ideal for everyone.

I'm glad we're all not alike or this would be one boring world (unless everyone was like me)"

Point here is that when Norton themselves made slight alterations to the Commando steering geometry, several less experienced riders crashed the bikes, so while a bike with modernised handling will suit most people just fine, it might not be good for everyone.

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Machines like Doug's are highly specialised, finely honed tools for one aim only — to win races, so of course they are not good for everyone. You infer that such quick turning bikes are unstable or twitchy. Not necessarily so. My Seeley-framed race bike is quick-turning but stable. I have been lucky enough to own and/or ride a number of modern race and track day bikes with quicker steering than normal and they were also stable at speed. This is because good chassis tuning includes work to the suspension and also the riding position. Some very quick-turning bikes are ridden regularly on bumpy real roads circuits and they don't misbehave if they are well set up. My own 996R Ducati with the steeper of the two steering settings of 23.5 degrees was perfectly stable on road or track, no front end tuck or head shake, but the suspension was very good as standard and was properly dialed in.

Thanks for posting this, Doug, I found it really interesting. A nicely-turned out, successful race bike.

I don't REALLY believe Seeleys are for sissiies..... I just like to needle my good friend Kenny whenever the opportunity presents itself.