tweeking the steering head

Rohan said:

But we diverge, as usual.

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Obviously no one in this thread has ridden a 1997 to 2001 Suzuki TL1000S (except for Madass140) with stock forks and rotary damper. :lol:
A girder fork and sprung hub would have been better.

That rotary damper was supposed to be the way of the future.
Can remember all the pretty colour-coded cross-sectional drawings of the workings of it - but not how it actually worked.
So what happened ??

Rohan said:

acotrel said:

The book also mentions Les Graham's fatal crash on Bray Hill in 1953 while riding a Gilera fitted with Earles forks. The bike used to shake it's head at high speed.

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Obviously they didn't have it set up right - should have asked BMW for advice.
Or just copied their design, ala normal motorcycle practice.

It can't have been too obvious, or Les would not have ridden it ?
All bikes used to have girder fork front ends once-upon-a-time, before telescopics were invented,
so there was plenty of experience with them, they reigned for 40 years....

But we diverge, as usual.

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The point is that the vice is often NOT obvious ! The bike can feel perfect, however when you come off a high speed bend and brake into a corner, it can grab you by the throat. Also you can have the situation where the bike gives a bit of warning, and if you disregard it and press on, it can all go wrong at the highest speed. Les Graham was the top rider of his time and he still got caught out. Earles forks were used on many bikes in the same era that telescopics were used, this has nothing to do with girder forks. I will say this once - if you get the steering geometry wrong it can bite you in unexpected ways. It always pays to proceed with care and work up to high speed slowly. Les had his warning, and it cost him his life when he ignored it.

Rohan, - A simple question : How many times have you crashed a motorcycle ?

Interesting question - how many crashes but its not alway pilot or bike fault and even when it is a number of things can splash together so harsh/fast ya really don't know what went wrong. That is how I learned not to crash, but facing facts I didn't know what was going on/wrong on THE Gravel so made myself face crashing knowingly till I mostly got the hang of it and bit different view - attitude about going around near and beyond hooked up limits.

So what I keep wanting to impress on rest of the world is how Peel both isolated and yet transmitted all the variables, tires shape temp and PSI, front axle angle to level or gravity, fork fluid and stiffness, lumps/dips in surface, fork angle, bike resistance to tip or falling on its own and wind gusts and eddies off forks and blockage by engine, side covers and spoke stirring blasts. I keep telling ya - you just don't know what you are missing out on lurking innately in the antique one of a kind isolastic Commando thin tube rubber baby buggy turofan powered UFO. In some our steep down hill turns I'd power rear out a bit so bike fell over into turn to feel like a P51 Mustang pitching over into a ground straffing run. I've done it in aircraft and errie similar G's.

acotrel said:

Rohan, - A simple question : How many times have you crashed a motorcycle ?

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Enough times to know it can hurt.
And cost.
But NEVER on Bray Hill.
And since I wasn't there, and haven't read the crash analysis report, and it may well have been aerodynamically related,
we could well speculate until the cows come home.

Given also that what happened 50 years ago may have no relevance whatsoever to this question, or this thread topic,
we will/should simply ignore such silly diversions...

here is the jig I used for sorting out the frames, bolted to the floor with a mark on the floor for steering head alignment.
this particular frame was having a section of front downtube replaced from what looked like crashbar damage.

That looks a supa strong jig to maintain iso points for various repairs.. I like it... Cutting and replacing tube section "releases" tensions the can be corrected prior to welding, As im sure your aware.......

I can visualise your Jig incorporating a head stock, mounting point that physically holds and maintains alignment of both iso's and head tube whilst cutting and welding of frame.. Also to align those frames that have no "obvious" deformations, but wont fit the jig.... Some will vomit at the idea of cutting frames to release "tensions" to correct alignment, but if thats what it takes, then....... Here we go!

Where are the cones and brace which lock the steering head in position in relation to the pivot, while the welding is being done ? It is normal to measure from the top steering head bearing to each side of a rod passing through the pivot mount. Even then the steering head angles must be maintained in two directions.