Great AMA Mid-Ohio Norton race video

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Was Dave Roper's bike in the rearwards facing shots of the clip? It looked like an XR750 to me. What was the 350 Harley Davidson - an aermacchi ? . There were sounds of two strokes in the clip. Perhaps I'm confused who was on which bike
 
Roper was on his 1970 H-D Aermacchi ERTT 350 Sprint- Mid-Ohio is a very technical track with lots of tricky elevation changes and a top-of-the-food-chain rider like Roper (who is a legend in vintage race circles) can pick up a lot of ground on a larger bike.
Kenny and I did switch bikes a few weeks ago at a film shoot, it was very interesting. Look up my 'race commando handling secrets' post if you want to see what was done to the bike- one of the things that I think makes it so smooth is the one-off head steady that Herb made for it which is not bolted to the frame in any way- it is just a teflon interference fit.
 
Thanks for making the video and for sharing it with us. There's more to it than people know.

As for that little H-D, those things were at the pinnacle of AMA 350cc roadracing when the Yamaha two stroke twins came along. LIght narrow handlers with engines that could spin. Faired and geared, big top speed. Ducati singles, even desmos, couldn't match them - inferior ports.
 
Unread postby J.A.W. » Thu Aug 09, 2012 3:01 pm
Has anyone tried elliptical shaped isos in place of the circular? could try rotating them cam-wise for best feel/location in the vibe plane?

Interesting concept I wondered on, about half way through grinding my front cushions to beveled profiles. There a two HUGE issues here to me, I call the Goldie Locks Paradox. Can chassis be too rigid or too flexy and how the tire edge hysteria handles the power hits. Peel's power unit sense and a whole bunch of other splishing-splashings that ain't coming from where its felt disappeared so nothing but pure traction issues showed up, which brings up the other isolastic wonder to me, how it seems to dampen the power hits on tire edge hysteria harmonics. Basically so forgiving even doodoo bird can get wild on it. If the cushions were made thinner in line with the tire pulse thrusts maybe traction dampening would lessen, maybe help hmm, dang I don't know so will try it. If ya want less engine vibes then thin the top-bottom of cushions. My prior feeling is road-chassis loads also carried by the cushions, so timidly decided on full circumference support, so far.
I paid big money to wreck someone else's bike learning what happens by over powering at worse possible points and times. It gave me the sense of too rigid while my Combat is definitely too flexy rebounding. If ya ain't hearing your tires sing pretty often at either end accelerating turns then might not appreciate the wonder lurking in isolastics.

by Doug MacRae » Thu Aug 09, 2012 6:16 pm
Roper was on his 1970 H-D Aermacchi ERTT 350 Sprint- Mid-Ohio is a very technical track with lots of tricky elevation changes and a top-of-the-food-chain rider like Roper (who is a legend in vintage race circles) can pick up a lot of ground on a larger bike.
Kenny and I did switch bikes a few weeks ago at a film shoot, it was very interesting. Look up my 'race commando handling secrets' post if you want to see what was done to the bike- one of the things that I think makes it so smooth is the one-off head steady that Herb made for it which is not bolted to the frame in any way- it is just a teflon interference fit.

Dang it Doug, you give a double hit to me, one on 3 point tamed isolastics and 2, Rooper's high handling loads on skinny tires. To further our education you might try a track day with only one swash plate functional at a time, then combos of two at once to see what's doing what. I've done it and last one I'd give up is the low rear one, then front then top. If only two to keep make it front and rear for me, if mounted above and below isolastics to help resist side tipping.

I'll take a big balloon tire any day over a narrow one for hi power, until the leaning gets over 45-50'.
 
Or try mixed media? drill rubber iso bush/disc radially, bond polyurethane plugs in place? Damp/kill the harmonic frequency moment?
 
yes sir J.A.W. I've heard that discussed and tired, but don't think it worked out as worth while, so far.
 
Pneumatics then? the solid rubber tyre was replaced with a gas bladder to good effect, just spit-balling here of course, Steve..
 
I love your thinking out of the box J.A.W., have heard air bladders also suggested but never tried. I've reviewed ferro fluids the voltage could vary to vary the viscosity, but mostly with fork action in mind.

I found Ms Peel has solved everything about handling so no longer seeking any more, just more power to weight ratio to enjoy spanking the tires off sports bikes quicker in public then main purpose to explore the faster ways around on non public places. Everything that matters gets through on Peel, nothing else, so nothing interfering with sensing the tire patch grip, the let go points of front or rear or both at once w/o any time&traction acceleration wasting drifts and slides - I absolutely detest, abhor and fear. Peel was so good I have a chance to upset the thinking and physics involved on two inline tire craft, but may have to add a 3rd driven tire to get the G's I crave beyond that.

To get sense of the dramatic phase transitions, consider phase 1 into phase 2 transition we all know, up to about 10 mph we can straight steer, but if ya try to counter steer that slow, WEEdogiedoo hi sides as fast as you can turn forks. That gives idea of how much load Peel can tolerate with ease and type loads that upset all others.

Worse condition for turning is being leaned on brake or holding a constant attitude, same with Peel, so she invites me into a series of sharply decreasing radii to make long-ish sweepers feel like a handful of short straight sprints punctuated by spikes of angular acceleration in between.

What i ran into is if chassis gets too rebounding flexy or too vibrating rigid then can't go fast enough into turns counter steering to pile up, store up the energy it takes to transition to next phase of faster handling. This energy building needs both speed and power. Realize when one is holding/forcing front tire in counter steer it forces bike to lay over more and makes rear dangerous to put much power on w/o sudden low side. Low CoG bikes like Harleys or Cdo's will lo slide wide off tangent with rear end leading the way, high CoG bikes like the modern elites will lift both tires up at once to fly off at a tangent horizontally in the air with rear leading till striking ground soon after to slide or hi side. There is a sweet zone of CoG I lucked out the Cdo has innately.

If ya can go in fast enough the bike will fall over on its own with rear power, front tire will flip forks into road following straight steer then pilot can add more fork inside turn pressure to lever down on rear patch, so fork is trying to hi side while rear trying to low side which twists the shit out of chassis, which if rebounds like flexy diving board or vibes like a metal rod at that point under power it will hi side dramatically. Peel just winds up twisting tight as I like pressing all the harder on rear tire edge so can increase power. Her rebound reaction is so small but so powerful its aim-able like a sling shot for a controlled crash just right to save us. Peel can hi side off front or rear.

But once beyond phase 2 counter steering the only ending of the turning loads is a low or hi side crash reaction. Flat tracker slide is just extension of phase 2 as still aiming front to outside, so better have Wide path to enjoy the ease as can't put on any more inward turning force or then becomes a tricycle with a boot down still sliding wide, like I did as a child on sanded sidewalks. Trying to turn in sharper while sliding wide flips tricycle pilot on noggin.

Being able to force rear patch hard into surface allows more power on its extra grip till point the front can lift up while leaned way over, so better have power enough to keep it up off surface till bike pivots sharp enough on rear patch pivot, its lined up right on touch down to cause a hi side just back to upright again. That's phase 3 style as always in surface contact. The 'down side' to this style on Peel is having to back off accelerating like a wheeling dragster forward to let front down, but its still fun because no momentum lost during the lull time before upright again to get back on power. Consider the power band required for this as the G's forces are forcing the front down and outward on the tangent rather hard, so extra hard to lift against that force, which does tend to force blood out of my head, which messes with vision field and focus. No way to do this if hanging off beyond CoG so not inline with chassis like a dragster launch where almost no one sticks anything out beyond gripping tight and low and back as possible. Also can not be done if slowing up into turns, only going in faster than ordinary cycles can take it. Uncanny Flabbergasting Fantastic!

Great AMA Mid-Ohio Norton race video
 
Excellent vid, thanks.

xbacksideslider said:
As for that little H-D, those things were at the pinnacle of AMA 350cc roadracing when the Yamaha two stroke twins came along. LIght narrow handlers with engines that could spin. Faired and geared, big top speed. Ducati singles, even desmos, couldn't match them - inferior ports.

I remember them well over here when they were mixing it with the TZs in the early 70s. They had the legs of my Ducati 450 in classic road racing during the 80s. Like the TZs, they were proper privateer GP machines and they showed their class, while Ducatis were road bikes that needed a lot done to them to make them go quick.
 
There are both H-D/A 4T singles, & 2T twins, it was the twins that won G.P. world championships though..& Hobot, have you heard of "dyna-focal" anti-vibe engine mounts? as developed by Bristol Aero for their big sleeve-valve radial aircraft mills?
 
No J.A.W i haven't nor have any reason to seek them out. Ms Peel is totally solved for my meager needs as regards her uncanny disappearing act and totally neutral non-athletic power lean G handling, The only thing significantly different chassis wise from Racer MacRae is Mr. McBride made his rather rigid with 3 robust non compliant swash plates while Peel only has one robust link, her 'rump rod'. The front and top links were just scab on experiments back in '03 to see if vibes transmitted, but the front nulled the forks road following hunting and the top nullifed the wind gusts eddies jiggles. So worked up to find limits, knowing she'd never match the super school bikes with fat race meats, to absolutely freak out getting no hints of upset easy matching the school ride G's, then went insane trying to upset her yet never could. After that first test fling I lost my respect for other cycles cornering ability. Either I've lost touch with reality or there is something different with Peel than any other bike. Only thing I can sense is her 2 wimpy links allow steel frame to articulate at iso's and tubes to absorb weird surfaces with wind hits > to pass right though like a flag in the breeze, also to take up the tire vector-traction conflicts, plus twist up like torsion spring to store energy but releases to Neutral relaxed state w/o going past it to rebound. Sling shots are like that, can stretch way back and just ease off for nothing or stretch and let go for the SNAP! All's I can feel for the rest of you'lls is ya might not know what's ya missing out on and likely don't realize how close to disaster you ride w/o even knowing it.
 
Thanks for sharing, I shall do an iso Commando but I am undecided whether to go the road-bike look,[very stylish/cool/correct] or put the mill in a superlight nimble 250 G.P. chassis for dynamic reasons, maybe I`ll vivsit you for 1st hand mindmeld purposes?
 
Someday may be able to display Peel in way that makes sense but my hobby goal is best handling cycle for fun and some magazine shoot outs if they'd cooperate. You know what my tool of choice is and why. Also want to see if good enough to take on 4wd rally cars too as they steer and use similar lines through turns as Peel. They can use phase 5 handling-steering like Peel, so only hope is out sharp em with phase 3 and 4.
 
Try Cycle World, their editors are Commando riders/fans & they do an ongoing 'American Flyers' pictorial series on hot/sexy classic bikes.
 
Yes my bud Wes gave me a subscription last few years and where I'd check in 1st, which as I ain't got nothing but hot aire so far, should tell them they need to do a story and evaluation with racers bikes like MacRae's. Vintage classes have rules many try to cheap on but Peel is a blatant outlaw.

BTW the opening scene where Doug starts up so we hear the deep throbs was very pleasing presence to sense what's to come.
 
Dances with Shrapnel said:
Ah, er, ah, it's a 350 Harley Davidson that Dave Roper was riding :oops:

Well that is really entertaining to watch old-man Roper run with 750s on a 350. If you freeze the video when he passes you can see a single small exhaust pipe poking out the right rear, not the two big meggas a 750 would have.

The bodywork and paint Roper has on his bike is the type that was originally developed for the 68' KRTT 750 side-valve bikes, I think it was designed at a university's wind tunnel in California back then. At Daytona that year Harley kicked the shit out of everyone else.
I think in the late 1980's Roger Reiman got his original 68 Krtt out of mothballs, took it to the AHRMA vintage race at Daytona and got first place with it beating Dave Roper on Ianucci's Matchless G50, the same bike that Roper raced at the IOM.

After 68' Harley kept that bodywork and paint pretty much for the rest of it's race program, on through the early 70's on the xr750s, and then it was used again in the 1980s when Jay Sprinsteen raced the Lucifer's Hammer XR1000 in Battle of the Twins races and did very well.

As far as isolastics go, I never like them, they are an engineering compromise, taking power from the engine and turning it into radiated heat. The Japanese would not have produced a farce like the Commando in the first place, but if they were asked to put a band-aid on it they would have used a balance shaft.

A balance shaft would not bleed energy like isolastics, it would store it like a flywheel and feed it back to the drive on upshifts. a lighter flywheel could be used on the engine then. Maybe someone like Hobot could make up a new engine cradle for a Commando with a set of nice bearings to hold a gilmer-belt driven balance shaft. Then the engine/swingarm could be mounted solid to the frame eliminating the heavy Isos and improving handling...
 
beng, I'm fascinated-addicted by handling phenomena and acceleration that takes front tire out of traction effect, straight ahead or laid full over. Obviously un-tamed isolastic design was created for pilot comfort and frame protection not for secure handling. The only reason to eliminate the isolastics is the dangerous handling onset when front tire is pointing one way and the rear another and their traction on surface effects differ in force vectors the chassis must resist or take up >- bad juju.
Vector = a force arrow with a magnitude and a direction. After Ms Peel I see the whole cycle world handling concepts differently than any one else but MX bikes horizontal in deep dirt ruts or ice spiked speedway racers accelerating to enter turns to fall over w/o steering effort or sliding wide, but doing it on flat tarmac w/o any banking in narrow confines.

Mr MacBride's innovative construction and racer MacRae intensiveness have done the experiment that was keeping me awake too often, What happens if isolastic engine mount was installed in essentially rigid chassis? It seems to behave similar/as well as the rigid rigs. As Doug put it, " I give up nothing in handling to those Seely's". Well dear sir that just ain't good enough for my G glee anymore. I might as well have a foot forward comfy chopper for that level of hanging turns. i've studied the chopper handling too, as Peel was half of one to find they too have to depend more on rear lean-slide steering than front and tear it up with flat trackers on dirt or stunting on parking lots, minus the stoppies, though they can't stop like Peel to be tossed over the bars with rear still in contact. I need butt velcro and ape hanger bars to stop shorter, so Peel won't have no clip ons, No Sir Ree Bob. Ears end up near hands for straights on 'her'.

Beng you are the only other one on forum to discuss the power hits on the drive train to tire patch so far. There is lots of this discussed under the "Big Bang" theory which concerns applying POWer Pulses when laid far over and coming out of turns. This is the second area I find my tri-tamed steel spaghetti tubed isolastic Commando shines brighter than all others, hooking up power/torque straight up or scraping. My course on this were steel wheel roller skates then bicycles on sidewaks spread with sugar sand, then 2 stroke on sand and rock pit graveling, then P!! dragster behaving the same on any surface, then THE ever-loving Gravel on factory Combats and SV650, then Code's School on Nina 900's, then on Ms Peel.

Note the decreasing radii behavior but not hooking up so good while only counter steering.
[video]http://www.youtube.com/watch?feature=fvwp&v=eQf_8-qtN0c&NR=1[/video]

Adv>> to see act, note the straight steering with and w/o leaning and no need of front to turn sharp as he likes. Note @ 50sec the hands off straight steer by unassisted natural lean only. Yes I seek to master a number of his moves. I've seen motorcycle do this too, just not time to hunt the video.
[video]http://www.youtube.com/watch?v=bhjYQFDNXps&feature=related[/video]

Now back to the power pulses and delivery efficiency. What you'all don't yet appreciate because ya never been on a totally neutral motorcycle with innate power dampening on tire hysteria is a power cycle needs 3 suspension systems, one for the road lump/dips, one for the side forces of turns and wind pressure and one for the tire thrusting. Ms Peel reveals it all and THE Gravel teaches all. Its all about energy flows and resonance of vectors, once ya get to limits of power lean and traction. CoG comes into play too. What I've seen in video of best riders on best elites holding max lean and power slightly loose in grip, is they can suddenly pivot on CoG to lift both tires till essentially horizontal and fly off the tangent, taking others out.

On the ones that don't pivot off CoG its the traction that lets them down first, though both combine as G vectors lighten the tire down force, zip there goes another good racer down. Sand on cement on rock hard tires and tire howl, squeal, chirp on soft hot race slicks has a resonance zone they loose their Van der Wall's ionic bonding resonance so surface interlocking drag is lost. Put rubber eraser on glass and tip till slides off, then vibrate the glass or rubber and less tip to start sliding, then once sliding its self re-enforcing vibrations, which sonic effects are still a great mystery in land and snow slides carrying so far away. Not to me on THE Gravel or quick sand, or perfect tarmac when resonance hits their liquifying zone. So yes the isolastics take up some of the power in the hits to tire patch by taking the peaks out of the spikes and delivering the rest while tire rubber layer is able to handle it.

I'm more a stunt rider than racer and stunt riders live to break free for more control. On the rigids I loose grip more from the buzz into rear than the power itself. This shows up as either abraded away rubber or melted lost rubber but there is an in between zone that smears the rubber out. Abrading lost of traction chirps, melting lost of traction screeches, smearing grip hums/howls. So my tool of choice is flexy w/o rebound energy storing, road wind resonance passing chassis with power spike dampening to pilot and tire patch isolastic Commando. I so remember the intense G forces on Ninja and SV on non DOT heated tires at fouling limits nailing throttle hoping for more thrust only to loose it, then on Peel getting to same conditions on skinny dual purpose hard tires and having the front lift against the outward force with so much traction on rear hook up. Why is that?
 
Hobot, you are correct re the importance of empirical lateral suspension,Commando designer Bob Trigg speaks about it in that Best of British Norton video, & it is the same phenomena that crippled Ducati's G.P. bike when they went from the tubular steel space frame [with its frequency/flex modulus]to the rigid carbon chassis, [maybe they should be looking at the Williams J.P.N. Monocque design].
As for the Japanese would be Commando beater - TX 750 Yamaha -, well that wasn`t exactly a techincal triumph either...[`scuse the pun].
 
J.A.W. long ago lost respect for all nation's cycles, no longer concerned a whitworth on out handling them, just need way more power to weight to take Peel turning advantage to higher speeds quicker. What I do not yet know is what size rear and pressure to run. Already explored 150 size to 170 and 100 to 120 rear, so leaves 130-140 to try. I also don't know if hobot Roaholder's or Lansdowne forks are safer but Peel was not been limited by forks so may not matter. When ever I get a wild hair to press my modern into turns like Peel effortless handling I get suddenly reassured they are dam dangerous corner cripples, rear skips out or front juddering into slide outs. Depending on the CoG of the cycle, ie: inline 4 or V twin they will fight like crazy to hold down or fight like crazy to arise back up. Modern hinge in those condition by way faster and harsher once onset than a sloppy un-tamed Commando.

I mean to say. do any of ya know what fun it is to leave black strips going into turns where everyone and their sister is hardest on brake. Alls I can say further is its anti-climatic by time apex relief arrives. Get ya crash done early then spend rest to the turn in crash recovery let off mode.
 
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