Wheel hop

[Steve]

Or, ... maybe just need an upgrade to the front brakes. :-k











While doing a stoppie, the rear wheel won't hop AT ALL.

.

 

[Lorenzo]

Rob, I do not know your level of knowledge on the matter, so forgive me if I say something obvious to you;

When a shock is compressed, the brunt is taken by the springs, that, if not restrained, will bounce back harshly.

So it must be introduced an "hydraulic brake" which prevents the shocks from "pogoing".

In a shock you might have three adjustments:

preload, you simply rise or lower the point of intervention of the springs;

damping, also known as "compression brake" which is designed to smooth the action of the springs, again;

finally the "rebound brake" which prevents the shock from fiercely recoiling, under the thrust of the spring, with adverse effects on the stability of the machine.

I personally like the approach of addressing the problem by looking at it from an 180? which is correct both academically and practically, so it holds true pointing to the weigth transfer from rear to front, during braking/decelerating, but if I was to say to you that, applying the rear brake, along with the front, is going to help the stability of the vehicle, whould you be surprised? Why? because braking transform part of the revolving momentum on the rear wheel, in straight and parallel to the ground, motion, or rather friction, contrasting the tendency of the wheel to "hunt" and trying to capsize the bike.

The above, to make the point that as bwringer said, the equilibrium, that in our case, opens the doors to a gainful ride, is attained by the positive combination of a moltitude of factors.

Going along the line of the front forks, you could also benefit, provided you had enough turf, from rising the upper triple, relative to the fork tubes, in so doing, contrasting not only the noise dive but, (no, no I am not going to talk about rake and trail....)

But, starting with a lame horse (being the worn out component), is not going to win you any race.

 

[Guest]

I just hope he is going AGAT this time around. I have never felt anything like this on either my 750EX or 1100ED in any state of suspension.

Same here and my bike has 59,000 miles on it. I make sure my suspension components are always up to snuff. The only time I get any rear wheel hop is braking on washboard roads and then you need to feather the rear brake on those.

 

[posplayr]

Handling in a vintage bike is not just one or two things -- it's a system with many interrelated parts. Your particular issue could have several different overlapping causes. You'll need to look at several different things to make improvements. At the moment, the stock shocks are the most obvious limitation in your bike's overall "system", barring mechanical issues. Until you fix that, changes to the front end will have little effect.

In terms of priorities, first make sure there are no mechanical issues, like bad swingarm or steering stem bearings. Make 110% sure you're starting with a stable, perfectly functioning frame. Do NOT assume anything and do NOT skip this step. Take the rear wheel and shocks off and check the motion of the swingarm carefully. Remove the swingarm pivot and grease the bearings. Upgrade the steering stem bearings to quality tapered bearings if that hasn't been done yet. Make sure everything is straight and there's no binding. Check the wheel and sprocket carrier bearings carefully.

Make sure the brakes front and rear are tip-top -- stock GS brakes work astonishingly well with fresh innards, pads, and stainless lines. Make sure your rear brake pivot isn't binding in the frame.

You've already done the springs in the front fork, which is where most start because they're relatively cheap and the positive effect is dramatic. It's a fantastic start, and it gets the front end 90% of the way there.

Next, upgrade the rear shocks. The stock shocks were junk 30 years ago and age hasn't improved them. Yes, I know some folks are saying this particular problem could be in the front, but I think they may be assuming you've already upgraded the rear, or that the shocks are functioning correctly. They are not. Until you fix this, you can dink around with the front all you want without making much difference in handling. In other words, you've already started by upgrading your front end, so the limit at the moment is the rear shocks. Upgrade these so you have a predictable platform. (the minimum is Progressive or Hagon shocks for around $220 - $250 a set; the Bitubos above are interesting, and there are several other brands such as Ikon.) Don't waste your time with the $80-$100 Chinesium shocks. Some have also installed slightly longer shocks to quicken steering.

Once the rear end is behaving, turn your attention back to the front end. Some 1100E owners disable the antidive crap, and lots of GS owners have installed Race Tech Gold Valves to improve our primitive damper rod forks.

Once that's done, then some people install a fork braces. This is sort of the last priority, and to a degree a fork brace is a matter of taste.

I agree that most everything is interrelated as described, however the black GS1100EZ/ED shocks are generally pretty good and even if 35 years old. If what Rob is describing comes from just "pulling the front brake" to haul down the bike's speed quickly, I would be inspecting both steering tube bearings and the swingarm pivot bolt to make sure they are in good shape and change out with good waterproof grease if any doubts.

When I started riding my old GS70EX in the twisties, I made it a very distinct practice to haul down the speed abruptly before entering any corner, release the heavy brake to regain a level attitude and then countersteer into the turn, and then back on the gas after the turn. These are generally tight mountain road type turns (30-40 mph). The FRONT ONLY braking was exaggerated so I developed confidence with the coordinated speed reduction and attitude adjustment coupled with APPROACHING the corners with TOO MUCH SPEED. If there was any of what Rob was describing I would have been in the ditch.

If anything this bike should not handle as well as an 1100EZ/ED and it was other than progressive springs and Hagon rear shock bone stone stock running on various tires including the Avon. Rob what tires are you running and how old are they?

At the time that bike had progressive springs new oil and a set of used $75 Hagons (the 750 shocks are not the same as the 1100) and I don't remember any such shuddering. Of course the steering bearings had been swapped out and the swing arm was in good order.

My only point to Rob, is there must be something wrong that is more than the rear shocks.

 

[Rob S.]

Less than 1k miles on Pirelli Sport Demons, front and rear.

It seems to me this wheel hop is why 'slipper' clutches were devised.

All bearings and bushings have been checked. I think slowing down is the solution (unless a slipper clutch can be retro-fitted - see my new thread).

Let me know when it's time to start packing up the side covers.