Legend John Surtees riding his Norton

This Rare piture is of the Legend John Surtees riding his Norton.



A striking freeze frame of corner loads on vintage bike and pilot.
Its more my style, back and centered nothing hanging out from CoG to keep more mass over the rear patch. Looks to me like he's just about maxed out in phase 2 handling. Ie: leaned with front tire slightly aimed to outside of turn. Front counter steer is tripping bike down while rear trail attack angle is trying to lift bike back up. If front lets go in this state > hi side, if rear spins out first > low side. Inbetween is chassis twist and release we call THE Hinge in Commando's. In other bikes its called no warning crashing going a bit harder just prior.
Note the low rear end by frame angle to road, implies the front is being lifted unloaded in line with fork spring.

Can ya picture what would happen if he kicked rear on out and at same time snatched forks into straight steering to follow road curve direction?

Can ya picture what would happen if he had power and traction to finish lifting front completely out of traction?

Can ya picture what happens to twist-torqued chassis and suspension in either of the above transition states?

hobot

hi hobot,great pic,although he prob did,nt know at the time what he was doing ,i think he,s rear wheel drifting or as the young uns say "laying a darkie" the only man on the planet to win world championships on 2 and 4 wheels,now thats we call a legend

Thanks Chris, especially as you confirm what I sensed too, that he is slightly overpowering rear approaching max grip of 10% slippage. I ride like that too, at times, on Gravel and tarmac so can assure you he must know exactly what's he's doing as his professional job, even if I don't feel like I fully do and may never.
What sinks in to me looking at the photo is how he's got most the mass and momentum focused on the rear patch as he takes bike to max apex loads and about to let it rebound-relax into more upright straighter exit of turn.

A slow mo video would reveal how steady or wobbly he let it get in this turning rush. To get past this state and not back off, will cause a sudden reversal in loads and effects of pilot inputs. More power looses acceleration but swings or leans bike, less power grips better and thrusts forward on crank momentum.
Brakes don't slow but skew bike and change lean angle suddenly on CoG and line of ballistics. Extra power trips bike down while let offs jerk it back up, but little speed change in this short time interval > But Boy Howdy lean and aim sure does!
If power and traction enough front is lifted to useless and can twitch sides faster than humans can follow or preform. Similar to sail boat boom on a tack change, you must duck-dodge it not resist it.
Only two bikes I now of, both isolastic rear linked Commando's being neutral enough to allow pilot to just let go and let God fly em to faster orbits.
A steering damper absolutely prevents this self correcting fast action = SPLAT.

hobot

The ' Grand Prix ' Avon rear tyre then was a dead ringer for the early Roadrunner Highly Hysterical ( Hi Hysterisis ) rubber road tyre ,
with the contiuous edge bead so there was no tread squirm ' at the giddy limit . I think surtee's advantage was he didnt get giddy !

So being highly dramatic on the lighter bikes ( than Gillerra's etc) was somewhat tame in contrast to traction availabe by 1980 ,
Michilen and Perrili Hard case tyres with grippy rubber you could tear of in a long race. I think yhey looked to get a few races out
of the tyres in the 50s . At the limits any uncoordiated inputs could have he rider as a passenger untill speed bled of.Hopefully
not instataeneously .

Rideing on a borrowed rear wheel with a square section ' Speedmaster Mk II ' ( indeed ) had throttle steer and drama available
at modest lean angles and moderate throttle settings .' We dont know how lucky we are ' with modern tyres fitted .
Hydious Nylon 400 18 rears up whoopy hill corners had the rear going outwards out of every dip . Gross throttle movements ,
or ' stuffing it open ' would have you on your ear , head , or in the ditch etc .

The racing tyres in the 50s wernt a lot differant . Sealed roads wernt in the majority previously , tyres were starting to be
developed for sealed roads only . Note , Starting , to be . Old canvas cased things, the rubber was like an erasser !

After reading the two responses from hobot and matt, I am convinced they are either related or steve now has an alter ego I like the picture, thanks.

britbike220 said:

After reading the two responses from hobot and matt, I am convinced they are either related or steve now has an alter ego I like the picture, thanks.

Click to expand...

That idea has crossed my mind more than once.

For some time, Avon (mabe Dunlop) produced a "tiangular" tire that had a very small rounded profile at the point where it would touch the road if the bike was upright, then flat sections each side at an angle that would lie flat on the road in a high-g turn. I think Peter Inchley used them on the works-entered Villiers Starmaker powered 250cc TT racer in 1967.

I believe they were sold to street riders for a while.

frankdamp said:

For some time, Avon (mabe Dunlop) produced a "tiangular" tire that had a very small rounded profile at the point where it would touch the road if the bike was upright, then flat sections each side at an angle that would lie flat on the road in a high-g turn. I think Peter Inchley used them on the works-entered Villiers Starmaker powered 250cc TT racer in 1967.

I believe they were sold to street riders for a while.

Click to expand...

Aren't the K81 TT100 tires like this?