Ducati.ms - The Ultimate Ducati Forum banner
  • Hey Everyone! Enter your bike HERE to be a part of this months Bike of the Month Challenge!

1 - 15 of 15 Posts

·
Registered
Joined
·
300 Posts
Discussion Starter · #1 ·
Hey all,

Well we had an awesome weekend here in the NE after a long rainy week. Me and my buddy rode a little over 100 miles on Sunday, and all was good.... until my friend who was leading decided to make a left hand turn last minute. We were only going about 35 MPH, when he decided to hook a quick left, the road was a bit chattered, and as I braked to slow down, I guess between the forks going up and down at a fast rate and quick decision to brake the front got crazy and started to skid and hop up and down.

This same thing happened to me when I first got the bike (I did not have a steering damper then), and the wheel started to flop all over the place. Yesterday, however, the wheel tracked straight, it just hopped up and down.

Now I was quickly able to react, and let off the brake and reapply. Is this this a weakness in the forks? Its not like I was trying to lock up the wheel, but is this what I have to expect when I apply the front brake on a ruff road?
 

·
Premium Member
Joined
·
1,861 Posts
Rebound damping too high?

I'm no expert. I've only read a few articles about suspension setting, and played around with my own.

If the road is "chattered", perhaps your wheel locked up because it was floating in thin air, rather than being turned by the road. This could be caused by too much rebound damping, and/or inadequate preload.

I'm happy that you didn't fall or get hurt.
 

·
Banned
Joined
·
2,916 Posts
Now I was quickly able to react, and let off the brake and reapply. Is this this a weakness in the forks?
no, that could have probably happened with
any other fork too.
it is that the front wheel needs some load on it,
to be able to get the brake forces to the ground.
with your panic stop, you typically brake too hard
from the beginning, giving the front end no time
to sink in, leaving the front wheel skidding "all
over the place", especially if the road is "chattered".

cheers.
 

·
Registered
Joined
·
300 Posts
Discussion Starter · #4 ·
I am going to go back to that road sometime and try and recreate the scenario to see what happens. From what you both said, it sounds exactly like what you described wheel was floating on the bumps with no load, and the brake just skidded the tire along.

My only concern is that i am pretty sure I did not apply the brakes to aggressively.
 

·
Registered
Joined
·
1,410 Posts
I had a very similar experience, my front wheel didn't lock up but DID "chatter" severely as I came to a hard stop. It was the first and really the only time it had done that, so I made sure the next time I was on the same road to check it out. Sure enough, there were ripples in the pavement that my suspension couldn't keep up with under the load. It's never happened anywhere else, but I hope that my "new" S4R forks might perform differently. Maybe I'll just go back and try to replicate the chatter if they haven't re-paved.
 

·
Registered
Joined
·
167 Posts
Hey, its just my opinion, but I wouldn't go trying to get your bike to misbehave again. Don't go trying to hurt yourself.

I've had this same thing happen on my 1098. My tech told me to look at my rebound rates.
 

·
Registered
Joined
·
985 Posts
Experiences like yours led me to replace the heavy steel OEM wheels on my GT. I found that they were so heavy that they kept the suspension from properly doing its job. On poor road surfaces, the wheels would quite often begin to bounce uncontrolled by the forks and shocks, just as you describe.

Light alloy wheels cured these problems. I'm otherwise running the stock suspension, which now has no problems in keeping up with road surface irregularities. The ride is now firm but never harsh, just as I like it.
 

·
Premium Member
Joined
·
1,625 Posts
Experiences like yours led me to replace the heavy steel OEM wheels on my GT. I found that they were so heavy that they kept the suspension from properly doing its job. On poor road surfaces, the wheels would quite often begin to bounce uncontrolled by the forks and shocks, just as you describe...
+1 on this - exactly what i was thinking as i read your first post. when you hit a bump the wheel starts travelling upwards and the heavier it is the more momentum has to be overcome by spring and compression damping. the wheel wants to keep going up and if your forks can't resist it adequately it will un-weight or in some cases actually leave the road surface which significantly affects braking.

lighter wheels make a huge difference, especially the combo on the gt of very heavy wheels and softly sprung forks.

interestingly, too much rebound dampening can also be a problem, as the suspension "stacks up" - in other words, with repetative bumps (chatter) the suspension is unable to return back fast enough and loses a little bit of travel with each successive bump.
 

·
Registered
Joined
·
1,071 Posts
Hey all,

Well we had an awesome weekend here in the NE after a long rainy week. Me and my buddy rode a little over 100 miles on Sunday, and all was good.... until my friend who was leading decided to make a left hand turn last minute. We were only going about 35 MPH, when he decided to hook a quick left, the road was a bit chattered, and as I braked to slow down, I guess between the forks going up and down at a fast rate and quick decision to brake the front got crazy and started to skid and hop up and down.

This same thing happened to me when I first got the bike (I did not have a steering damper then), and the wheel started to flop all over the place. Yesterday, however, the wheel tracked straight, it just hopped up and down.

Now I was quickly able to react, and let off the brake and reapply. Is this this a weakness in the forks? Its not like I was trying to lock up the wheel, but is this what I have to expect when I apply the front brake on a ruff road?
Yeah, not only does the Sport Classic line LOOK retro, it also HANDLES retro...or even worse. I can't remember my bikes from back in the day being nearly as scary to ride as the Sport Classics in stock configuration, and half of those bikes were Kwaka triples.

Your forks are bottoming out. This is unfortunately a common and dangerous problem with the inadequate stock Sport Classic suspension, wheels, tires and tire tubes, all working together to toss you off your bike or into hard inamimate objects. The problem is exacerbated if you weigh anywhere near 200 lbs or more. The steering damper will not help this skittering pogo stick thing -- that's a whole other problem, but related.

You need to get Ohlins, Showas off another Duc model or have your stock forks totally reworked by Traxxion or someone similar. You need to get rid of your stock wheels and tires and replace them with lighter tubeless wheels -- either alloy wheels or Alpina spokers -- and modern sport tires.

Yes, this will take effort and cost money, but I assume your neck is worth it to you. Once you replace these items, you will have a really nice handling bike instead of the tankslapping pogo stick you experienced.

I would not bother with half measures like trying to gob up the inside of your rims in a vain attempt to make them tubeless -- that could conceivably make them even more dangerous than the stock wheels with tubes. Nor would I bother to replace springs, fluids, pvc pipe spacers and what not to try doctor up your stock forks. The stock rear shocks are poor, so they should be replaced, too.

Good luck!
 

·
Registered
Joined
·
555 Posts
well, I don't quite agree with that. Replacing the rims with something lighter and getting quality tires makes a massive difference. The stock suspension is fixable, without being replaced - perhaps not for track use but certainly for the road.
 

·
Registered
Joined
·
1,410 Posts
Sport1000 points out some of the "less-than-optimal" features of our stock bikes, but to compare them to true '70's bikes handling seems way off the mark to me. I too rode the old beasties, in my garage next to the GT1000 lives a '74 Suzuki GT550 that's licensed and ready to roll. And it's handling is not what I think most folks would expect.

See, back then the suspension, wheels, and brakes were crap. Pure and simple. It was all we knew. So even then, comparisons were made and mods were done for "improvements". But underneath it all, the steering geometry was WAYYY different. My GT550 does not turn. Period. I've got to throw my weight all over the place to force a lean. But it is pretty stable, with nary a head shake. The original Ducati bevel drives had, what, 35 degrees of rake!?! And it was renowned for it's stability.

Point being, yea, the stock front suspension isn't really up to the task with the modern relatively steep 24 degrees of rake. But there's no comparison with the old Kawi triples, they had really flexible frames and (I think) 33mm fork tubes.
 

·
Registered
Joined
·
28 Posts
I've locked up the front on my PS twice now. Once on stock rubber, once on corsa III's. It believe, both times it was a combination of not having enough heat in the tires and the fact that the rake is more than your typical sport bike. I do not think I am getting good weight transfer upon braking. I intend to dial back on the front spring preload before I get back on the road.
 

·
Registered
Joined
·
164 Posts
I guess I haven't really had a good enough handling motorcycle! I have had a Yamaha xs1100 and a Honda 360t, and I thought the Sport Classic was a dream in terms of handling compared to my other bikes. I really feel like I can push this bike through corners and it does great. I can't say anything bad or good about the brakes, as I have not ever really had to stop in a hurry (besides practice) and they have always done there job. I plan on getting a set of softer brake pads to help out a little.

I would love nothing more than a set of ohlins, don't get me wrong. But for the money, I would rather have my heads ported and polished and install a set of cams. Everyone to their own!:)
 

·
Registered
Joined
·
1,071 Posts
Sport1000 points out some of the "less-than-optimal" features of our stock bikes, but to compare them to true '70's bikes handling seems way off the mark to me. I too rode the old beasties, in my garage next to the GT1000 lives a '74 Suzuki GT550 that's licensed and ready to roll. And it's handling is not what I think most folks would expect.

See, back then the suspension, wheels, and brakes were crap. Pure and simple. It was all we knew. So even then, comparisons were made and mods were done for "improvements". But underneath it all, the steering geometry was WAYYY different. My GT550 does not turn. Period. I've got to throw my weight all over the place to force a lean. But it is pretty stable, with nary a head shake. The original Ducati bevel drives had, what, 35 degrees of rake!?! And it was renowned for it's stability.

Point being, yea, the stock front suspension isn't really up to the task with the modern relatively steep 24 degrees of rake. But there's no comparison with the old Kawi triples, they had really flexible frames and (I think) 33mm fork tubes.

The Mach IIIs had a lot of bad handling habits but I never once had one bottom out and lock up on me when braking. The brakes would be the last thing you want to fail on any bike. The brakes on the Mach III were actually pretty predictable, even the front drum -- you just learned not to overdo it because they would fade. The steering damper, which I believe came stock from the factory begining in 1971 pretty much solved the tank slapper problem.

Of course, after the first couple of years, everybody who was paying attention knew what the "Widow Maker's" faults were. The Mach IIIs and H2s were actually a lot of fun once you realized they were basically just "point and shoot."

The problem with the Sport Classic is that they are sold as modern sport bikes in retro garb. To the unsuspecting, the fork, wheels, tubes and tires are a booby trap waiting to happen, especially if you're riding it like a sport bike.

When the little old lady in the Caddy pulls out in front of you, the last thing you want is for the forks to bottom out and the brakes/tires to fail.
 
1 - 15 of 15 Posts
Top