most britt rear shocks are ~ vertical

acotrel said:

I often wonder if the amount of travel in modern road bike suspensions is really necessary.

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If you had ridden on anything other than billiard smooth Australian 'highways' lately,
you'd know WHY longer travel suspension is a good idea !!

Lumps, bumps, ridges, valleys and the all too familiar potholes are just par for the course.
And then you get on the backroads, where unsigned washaways can launch you, bigtime.
Next to no suspension travel, no thanks.....

It definitely is a trade off between long travel and good handling,
but if you want to live to tell the tale.... ?

Rohan said:

acotrel said:

I often wonder if the amount of travel in modern road bike suspensions is really necessary.

Click to expand...

If you had ridden on anything other than billiard smooth Australian 'highways' lately,
you'd know WHY longer travel suspension is a good idea !!

Lumps, bumps, ridges, valleys and the all too familiar potholes are just par for the course.
And then you get on the backroads, where unsigned washaways can launch you, bigtime.
Next to no suspension travel, no thanks.....

It definitely is a trade off between long travel and good handling,
but if you want to live to tell the tale.... ?

Click to expand...

Sounds like a lot of the roads in the US. If it keeps getting worse we will need 14 inches of travel to run the interstate. Jim

I was always under the impression that race design led what appeared on road bikes etc. The obvious exception was the MX monoshock suspension which appeared on the mid 70s TZ750. It used to always be that race circuits were rougher than most surfaced public roads. Perhaps in Australia we don't get enough rain to regularly destroy the road surface ? The hydraulic effect of trucks squashing water into cracks seems to lift the bitumen - we don't get much of that happening. These days some of the historic guys are quite fast even with rigid frames- the race circuits are much smoother now.

acotrel said:

I was always under the impression that race design led what appeared on road bikes etc. The obvious exception was the MX monoshock suspension which appeared on the mid 70s TZ750. It used to always be that race circuits were rougher than most surfaced public roads. Perhaps in Australia we don't get enough rain to regularly destroy the road surface ? The hydraulic effect of trucks squashing water into cracks seems to lift the bitumen - we don't get much of that happening. These days some of the historic guys are quite fast even with rigid frames- the race circuits are much smoother now.

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big cold thaw temperature changes, snow salt or whatever it is they use these days destroys roads here yearly,

warm weather months are spent fixin winter damage,

and the beat goes on

acotrel said:

Perhaps in Australia we don't get enough rain to regularly destroy the road surface ? .

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You need to get out more Allan ?
There must be thousands of these signs even just in your neck of the woods,
if not tens of thousands of them. And there have been 3 huge and widespread floods in the past 5 years.
With the current austerity regime, there is no splashing the cash to repair them either.

acotrel said:

I was always under the impression that race design led what appeared on road bikes etc.

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Don't get too carried away with that race replica thingy.
Adventure bikes and most touring bikes have a reasonable amount of suspension travel,
and some of those adventure bikes are mega in the suspension dept.
Some of the seats are so high in the showroom I've wondered how folks get on some of them...

Commandos were pushed as quite a comfortable bike to ride, with a claimed ? 6" of front fork travel.
Even if the 6" wasn't quite there....

the future typical bike is already here

https://www.google.ca/search?q=yamaha+t ... 32&bih=957

comnoz said:

Rohan said:

acotrel said:

I often wonder if the amount of travel in modern road bike suspensions is really necessary.

Click to expand...

If you had ridden on anything other than billiard smooth Australian 'highways' lately,
you'd know WHY longer travel suspension is a good idea !!

Lumps, bumps, ridges, valleys and the all too familiar potholes are just par for the course.
And then you get on the backroads, where unsigned washaways can launch you, bigtime.
Next to no suspension travel, no thanks.....

It definitely is a trade off between long travel and good handling,
but if you want to live to tell the tale.... ?

Click to expand...

Sounds like a lot of the roads in the US. If it keeps getting worse we will need 14 inches of travel to run the interstate. Jim

Click to expand...

Hi

Does anyone know if the axial movement in the rear shocks (as referred to in the manual) applies when aftermarket shocks are fitted? (on a MK3)
I guess the reason on the standard set up is to accommodate sideways movement which seems irrelevant as the body of the shock swivels on the rod anyway so I'm a bit confused about why this is so critical

Cheers Jed

comnoz said:

84ok said:

norton rear shocks look ~ 45deg forward angle, any particular reason?

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It was the "in" thing to do in that time period. It gives you more travel out of a short shock.
I have found an Isolastic Norton actually handles better on the track with vertical shocks but they don't look as good. Jim

Click to expand...

thoughts on why better? pix of the setup?

84ok said:

comnoz said:

84ok said:

norton rear shocks look ~ 45deg forward angle, any particular reason?

Click to expand...

It was the "in" thing to do in that time period. It gives you more travel out of a short shock.
I have found an Isolastic Norton actually handles better on the track with vertical shocks but they don't look as good. Jim

Click to expand...

thoughts on why better? pix of the setup?

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That was pre-digital camera days so pictures are scarce. I simply moved the top shock mount back around 6 inches with a plate that went forward to the down tube for support. I had another pair of shocks built for the new geometry.

Think of it this way. If you were to remove the rear shocks and install solid struts in their place you would still have around 1/4 inch of rear wheel travel. Due to the angle of the shock the up and down motion of the wheel will result in forward and back movement of the cradle on the isolastic mounts. This movement would not be damped by anything except the small amount of damping from the rubber in the mount.

That movement of the cradle is still there when the shock is in place. Small fast movements of the shock are resisted by the hydraulics of the shock but there is no resistance to small cradle movements.

The difference on the track was the fact that I could hold a tighter line through a tight corner. The rear tire simply had better traction when all the movement was being controlled by the shock. Jim

comnoz said:

Small fast movements of the shock are resisted by the hydraulics of the shock but there is no resistance to small cradle movements.

Jim

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Wow! Does that mean that Commandos had separate high speed and low speed damping in their suspensions, just like modern high end bikes? Just another example of the far sighted Norton design engineers being ahead of the curve. :lol:

Ken

lcrken said:

comnoz said:

Small fast movements of the shock are resisted by the hydraulics of the shock but there is no resistance to small cradle movements.

Jim

Click to expand...

Wow! Does that mean that Commandos had separate high speed and low speed damping in their suspensions, just like modern high end bikes? Just another example of the far sighted Norton design engineers being ahead of the curve. :lol:

Ken

Click to expand...

Something like that....

comnoz said:

If you look at my bike you will see where I added metal plates to the rear frame loop. The place where the luggage rack is mounted is a shock mount. When I first put my bike together I didn't have a set of Commando shocks so I used some shocks from an old Yamakawahonda. They were a couple inches shorter than the Commando shocks. I used it for a year or so that way before I came up with some longer shocks. The first thing I noticed when I installed the correct shocks was the bike vibrated more, particularly when the rear suspension was compressed by a load or wave in the road. The canted rear shocks pull back on the engine cradle and load the iso bushings so they transmit more vibration.

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How did those long chunky springs miss the chainguard?. Is there allowance for axial movement or is that not an issue with the gas shocks you have on it?

Jed said:

comnoz said:

If you look at my bike you will see where I added metal plates to the rear frame loop. The place where the luggage rack is mounted is a shock mount. When I first put my bike together I didn't have a set of Commando shocks so I used some shocks from an old Yamakawahonda. They were a couple inches shorter than the Commando shocks. I used it for a year or so that way before I came up with some longer shocks. The first thing I noticed when I installed the correct shocks was the bike vibrated more, particularly when the rear suspension was compressed by a load or wave in the road. The canted rear shocks pull back on the engine cradle and load the iso bushings so they transmit more vibration.

Click to expand...

How did those long chunky springs miss the chainguard?. Is there allowance for axial movement or is that not an issue with the gas shocks you have on it?

Click to expand...

Back when I used to run a chain and a guard the aftermarket chainguard was cut away behind the shock. Now that I am running a belt there is no clearance issue. Jim

ludwig said:

comnoz said:

If you were to remove the rear shocks and install solid struts in their place you would still have around 1/4 inch of rear wheel travel. Due to the angle of the shock the up and down motion of the wheel will result in forward and back movement of the cradle on the isolastic mounts. This movement would not be damped by anything except the small amount of damping from the rubber in the mount. ..That movement of the cradle is still there when the shock is in place. Small fast movements of the shock are resisted by the hydraulics of the shock but there is no resistance to small cradle movements.

Click to expand...

Can this not be ' cured ' by placing a tie rod lengthwise below the engine , from the frame cross tube to the craddle, somewhere near the lower gearbox mount ?
Doesn' even need to be a tie rod . A strap of steel would do .

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That would cure the for to rear movement of the cradle, but it would also transfer all the for to rear vibration from the engine to the frame. Jim

Wow! Does that mean that Commandos had separate high speed and low speed damping in their suspensions, just like modern high end bikes? Just another example of the far sighted Norton design engineers being ahead of the curve. :lol: Ken

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Yes Ken it sure as hell did in Ms Peel. But not if only two cushions in rear iso and not if any of the links are close to pivots or iso mounting points, such as under of over mid cradle area or in line close to iso mounts. NO modern so far can match my properly tamed isolastic Commando - though I'm the only one so far to prove this by going against the limited wisdom of too rigid too rebounding construction. I do want to impress world that to get such power load handling of Ms Peel you can not just dive into turns like ordinary racers that pile up on each other - but must hit their limited counter steering loading 1st to compress and take all slack out the system before the magic of triple 3-axis suspension and dampening happens. Actually there is a 4th dimension of handling motion Peel revealed but over your heads to explain so can only demo once Ken's gets Peel engine here.

If ya think I'm just bragging and don't know what I'm talking about oh well that's exactly the impression I hope to dissolve very quickly on future shoot outs with craft that aren't corner cripples - 1000 hp rally cars up and down Pikes Peak, though I doubt they will risk much racing downhill like Peel invited me to. You can only see this level of handling in off roaders and ice spiked speedways but they hardly ever hit Phase Four so I also want to take on the robo-cycles coming online that are able to use straight steering advantage. I can not practice Peels cornering on moderns as they let go before they can load up the tension it takes to make bike fall over on its own when all hell breaks loose. Peel was great off road too and practiced herding both freaked out cattle and deer in their element only escaping Peel on their tail by jumping fences or tree falls so Peel had twist sideways to slow up in time down hill on grass or Gravel. Front has little to do with aim at Peels rates. If can't be hooking up enough power to lift front out of effect though apexes then its a dangerous corner cripple to me.

[video]https://www.youtube.com/watch?v=AKC8pSFg1Vw[/video]

How much suspension travel is there on the front and rear of a standard commando, and how do they handle when gassed hard in the middle of a corner when cranked right over at almost max. lean ? Do they inspire confidence by tightening their line, or do they tend to run wide ? I was surprised when Agostini used MX suspension on the Yamaha TZ750 in the 70s - it seemed to be a great leap forward, on a bike that I would have expected to be 'point and squirt'.

acotrel said:

How much suspension travel is there on the front and rear of a standard commando, and how do they handle when gassed hard in the middle of a corner when cranked right over at almost max. lean ? Do they inspire confidence by tightening their line, or do they tend to run wide ? I was surprised when Agostini used MX suspension on the Yamaha TZ750 in the 70s - it seemed to be a great leap forward, on a bike that I would have expected to be 'point and squirt'.

Click to expand...

With relaxed track riding on a mostly stock streetbike they are pretty nice and neutral -up to the point they push the front tire.

Beyond that individual setup is everything.

With relaxed track riding on a mostly stock streetbike they are pretty nice and neutral -up to the point they push the front tire.

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LOL!!! Relaxed riding can't stress anything so waste of time money track day if not getting scared almost crashing or actually crashing to get better grip on any cycle handling quirks and limits. Factory Roadholders allow a bit over 4" travel and rear shocks about 2.5". A HUGE reason I find all other road going cycles corner cripples is they lack fork travel to keep front in traction when lifting front out of effective traction on powered leaning. I have pushed on too many occasions my SuVee's heated race tire front on Race Tech fork innards to slide it out of control a few bikes lengths trying trying for all my might to even approach Peels rates on my well practiced commute route. No way can rigid frame short travel forks take the loads I crave on Peel. No way can rubber iso baby buggies even approach SuVee's hi powered corner crippled lean capacity. Watch the elites getting upset to see what I mean as they try to transition form every day commuting rates into uncontrolled off road like loose wobble states, the poor dangerous unpredictable things. I too was fooled into thinking modern cycles had an advantage over a Commando beyond just way more power to weight ratio.
Only my late's fathers chiding me I never finished anything made me show him by completing 1st Ms Peel I had no intension to keep - till 2-1-mega jerked me off seat and tri-links allowed this in far over decreaser paisley shaped turns. One of Ricochet Rabbit ridding camp challenges will have a few sections like this, one on the level another two on a slope, one each way, that can not be taken smoothly turning, only bizekly frantically faceting it like a gem stone cutter.

hobot said:

I too was fooled into thinking modern cycles had an advantage over a Commando beyond just way more power to weight ratio.

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I was fooled too. Still am. Guess I will stay that way until I see Hobot out winning a BOT race.....

Ugh if I saw maxed out vintage with world class pilots as any competition I'd not made a peep about Peel. I flat state you have no real idea of the handling capacity you now have with the rump link Jim. You've only gotten mere hints in the loaded down hwy wind gusts and hands off stability down to a stop. I may one the few with the balls to take a cycle beyond two tire traction not because I'm good at it or planned to but because THE Gravel and road hazards forced me but now crave it so so much nothing but a Peel linked Commando can get me there. Past Peel had to have rather more power than normal Combat = equivalent to more expensive vintage racers to pull off the handling level I'm hooked on. It takes deadly speeds in dangerous conditions to reveal the full worth of proper placed and compliant links. I'm more interested to race gymkanna against rally cars than stupid modern corner cripple cycles that buzz the snot out of tire patches. Peels got stunts not yet seen done w/o loosing control. I am not good at it to my mind but Peel was so I let her invite me beyond my own ability which surprised me how easy effortless it was on me. I know what effort it takes to try to control others and want no more of that shit.

NOTE I did not learn Phase Three and Phase Four on a Commando and came close to never trying it on a Commando but for fate to finally finish a stuck with project I'd lost interest in but to be rid of forever as obsolete clunker.
No name Combat lingered in shed boxes while i bought a handy modern and spent $1000's on corner school and modern upgrades down to non DOT race tires. Maybe you'all don't yet know what ya's missing out on like i do.