13 years ago.... GPX750R

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Re: 13 years ago.... GPX750R

Post by weeksy »

Wasn't you? Hmmmm dunno who it was then
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Re: 13 years ago.... GPX750R

Post by weeksy »

Potter wrote: Sun Jan 23, 2022 5:01 am 2ptjoe was a smashing fella, lovely family and very kind.

I remember you buying the GPX, I think it was your first 'project bike' and you swore never again, but I always liked the GPZ/GPX, I still think they look good now.
He still flaunts with the Mx thing, occasionally. So does 1 of the kids.

He's done a few trackdays again and has a few bikes, OW01 he's put gazillions into, Ducati 996R and I think the Hyperstrada still.
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Re: 13 years ago.... GPX750R

Post by Dodgy69 »

KungFooBob wrote: Thu Jan 20, 2022 5:49 pm Reminds me of my GPZ600, it was a horrid thing.

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I quite like that, never rode one and compared to modern stuff, well, but nice styling and colours, imo. 👍
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Re: 13 years ago.... GPX750R

Post by Skub »

Dodgy knees wrote: Sun Jan 23, 2022 9:19 am
KungFooBob wrote: Thu Jan 20, 2022 5:49 pm Reminds me of my GPZ600, it was a horrid thing.

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I quite like that, never rode one and compared to modern stuff, well, but nice styling and colours, imo. 👍
The GPZ1000RX was the daddy of the range and a major let down. Because the GPZ900R was such a groundbreaking bike,everyone was expecting a 900R plus. The RX certainly had more power,but took a big step backwards in handling. It wasn't such a bad bike if you didn't compare it to the 900R,but it was a disappointment. Kawasaki didn't improve much with the following model,the ZX10 either,it wasn't until the mighty ZZR1100 that they had another winner.

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Re: 13 years ago.... GPX750R

Post by Le_Fromage_Grande »

The 1000RX was a wildebeest, a strange handling bike.
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Re: 13 years ago.... GPX750R

Post by Bigjawa »

Le_Fromage_Grande wrote: Sun Jan 23, 2022 2:00 pm The 1000RX was a wildebeest, a strange handling bike.
Didn't they have the press launch at a track in the pissing rain and half the press bikes ended up wrecked after losing the front?
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Re: 13 years ago.... GPX750R

Post by Skub »

Bigjawa wrote: Sun Jan 23, 2022 4:46 pm
Le_Fromage_Grande wrote: Sun Jan 23, 2022 2:00 pm The 1000RX was a wildebeest, a strange handling bike.
Didn't they have the press launch at a track in the pissing rain and half the press bikes ended up wrecked after losing the front?
Yeah,the anti dive mechanism on the forks was a hard taskmaster. I seemed to recall it encouraged the forks into something akin to hydraulic lock. Brake hard once,it's ok,maybe twice ok too,then the next time is :shock:
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Re: 13 years ago.... GPX750R

Post by The Spin Doctor »

Skub wrote: Sun Jan 23, 2022 5:18 pm
Yeah,the anti dive mechanism on the forks was a hard taskmaster. I seemed to recall it encouraged the forks into something akin to hydraulic lock. Brake hard once,it's ok,maybe twice ok too,then the next time is :shock:
CBX550 had a similar anti-dive - my brother bought one, turned it up full and promptly crashed it.
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Re: 13 years ago.... GPX750R

Post by Le_Fromage_Grande »

Early GSXR750s had "anti dive" but all it did was increase the compression damping, you couldn't feel the difference between any of the 4 settings.
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Re: 13 years ago.... GPX750R

Post by Count Steer »

Dive seems to be an inevitable consequence of how forks work and reducing dive by stuff like compression damping just constrains their operation. Has anyone really solved that conflict? I know BMW have a well tested design but it hasn't made it into successful competition etc

(Should probably be a new thread but, as we're here...)
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Re: 13 years ago.... GPX750R

Post by Le_Fromage_Grande »

There are front suspension designs that don't dive, leading link forks, most hub centre steering designs, Hossack front end and BMW Telelever (which isn't a BMW idea BTW), but is a lack of dive what you want?
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Re: 13 years ago.... GPX750R

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Le_Fromage_Grande wrote: Mon Jan 24, 2022 10:23 am There are front suspension designs that don't dive, leading link forks, most hub centre steering designs, Hossack front end and BMW Telelever (which isn't a BMW idea BTW), but is a lack of dive what you want?
Intuitively, yes but clearly it's designed in and the overall geometry/performance copes with it. Does it benefit from it? Dunno, that's why I asked really. Why add anti-dive if dive is a 'good thing'?
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Re: 13 years ago.... GPX750R

Post by Skub »

Anti dive was a thing when front suspension wasn't very good. It was an attempt to make fork dive useable and controllable. More modern tech allows this to be done in a more efficient way using damping.
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Re: 13 years ago.... GPX750R

Post by Le_Fromage_Grande »

Count Steer wrote: Mon Jan 24, 2022 10:33 am
Le_Fromage_Grande wrote: Mon Jan 24, 2022 10:23 am There are front suspension designs that don't dive, leading link forks, most hub centre steering designs, Hossack front end and BMW Telelever (which isn't a BMW idea BTW), but is a lack of dive what you want?
Intuitively, yes but clearly it's designed in and the overall geometry/performance copes with it. Does it benefit from it? Dunno, that's why I asked really. Why add anti-dive if dive is a 'good thing'?
I think, as Skub has said, improvements in bike design have done away with the need for anti dive, I believe the requirement for anti dive largely came from Endurance racing using Z1000 and GS1000 engines that had to be mounted high to get good ground clearance, leading to some odd weight distribution. These bikes also have forks at least 50mm longer than modern bikes.
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Re: 13 years ago.... GPX750R

Post by Count Steer »

Cheers. It's interesting that all those early designs never really caught on more widely. They must have started from the assumption that dive wasn't optimal, or at least needed better control. Interesting technical/design issue though.

(The last bike I owned with conventional forks was a '79 CX500 :D but I've ridden a few 'long travel' suspension bikes - off road. The last bike I owned with a chain final drive was a BSA A7. I like low maintenance :lol: )
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Re: 13 years ago.... GPX750R

Post by mangocrazy »

First generation VFR750s (RC24) had anti-dive fitted on one leg, and it was as crap as all the other manufacturer's offerings. If you went over a big bump in the road on the brakes, the forks let out a loud bang, which was very disconcerting. I blanked off and disabled the anti-dive and it was an improvement in every way. As others have said, once manufacturers stopped using damper rod forks and went to cartridge forks, anti-dive disappeared into the dustbin of history, along with 16" front wheels.
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Re: 13 years ago.... GPX750R

Post by Count Steer »

Count Steer wrote: Mon Jan 24, 2022 11:41 am Cheers. It's interesting that all those early designs never really caught on more widely. They must have started from the assumption that dive wasn't optimal, or at least needed better control. Interesting technical/design issue though.

(The last bike I owned with conventional forks was a '79 CX500 :D but I've ridden a few 'long travel' suspension bikes - off road. The last bike I owned with a chain final drive was a BSA A7. I like low maintenance :lol: )
Just realised that neither of those last 2 points are true. I had a BMW F800GS ( hated it so much I must have deleted it from my memory!)
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Re: 13 years ago.... GPX750R

Post by Hairybiker84 »

I had one of those, took it in P/X for some 750 custom thing (god knows how I ended up with that), I was well impressed with it, 150mph bike I seem to recall, which was no slouch then. Perfectly practical real world motorcycle, not some race rep you're glad to get off after 40 minutes.
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Re: 13 years ago.... GPX750R

Post by The Spin Doctor »

Le_Fromage_Grande wrote: Mon Jan 24, 2022 10:23 am There are front suspension designs that don't dive, leading link forks, most hub centre steering designs, Hossack front end and BMW Telelever (which isn't a BMW idea BTW), but is a lack of dive what you want?
AFAIK the original Telelever design damped out around 90% of the movement of conventional suspension under braking... and test riders found it made difficult to judge how hard the rider was braking.

I believe in the production version, there's 50% of the movement of conventional suspension.
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