Time for a new ride... (ideas welcome!) | Page 9 | GTAMotorcycle.com

Time for a new ride... (ideas welcome!)

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shanekingsley said:
There’s so much I like about these ZRX’s, but what is the reasoning behind the weird split swingarm thing?

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It's a braced swingarm and sort of a callback to the bikes that inspired the ZRX from the late-'70s and early-'80s, I think. The stock Japanese bikes of the day had weedy swingarms and bendy frames that had long been overpowered by the huge power advances through the '70s. Braced swingarms were a go-fast item, just like aftermarket exhausts. Superbike racing was becoming a thing, with legends like Fast Eddie Lawson riding these race-modified bucking broncos like so:

1728871473336.jpeg
Braced swingarms, Kerker exhausts, modified airboxes, Stage III jet kits, porting and polishing, tampons in the sump, all were part of the scene that bikes like the Zed-Rex is trying to recapture. All of it infinitely cooler to me than the Bonnevilles, cafe racers, black leather jackets and Brylcreem scene, or the various other nostalgia trips that have gripped biking over the years...

Modern swingarms can be similarly braced, but in a much more complex way:

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You can see a real shift in swingarm fabrication between the SP-1 version of the RC51 (2000-2001) and the SP-2 version (2002-2005) here:

1728872350014.jpeg

The older one on the right is a traditional fork swingarm with bracing welded on. The newer one isn't made of box-section steel anymore and has more of a monocoque design with much more complex elements. It's much lighter and a bit stiffer, and more easily tuned for things like lateral flex.
 
Lightcycle said:
No need to remind you to post pix of your new ride, right?
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I'm trying to get ahead of myself here. Hanging desperately on to the illusion that I'll be able to walk away if the bike isn't right. Have only looked at pics and studied the mechanic service history the owner has sent. While everything seems to be ideal based on those, I've looked at enough used bikes to know how many serious flaws can be hidden with carefully framed pics and selective sharing.

That said, I'm also renting a UHaul trailer and bringing cash, so draw your own conclusions...
 
Nobody takes a trailer with them to kick tires. None-the-less a rented one.
Congrats on the new bike.
 
Priller said:
It's a braced swingarm and sort of a callback to the bikes that inspired the ZRX from the late-'70s and early-'80s, I think. The stock Japanese bikes of the day had weedy swingarms and bendy frames that had long been overpowered by the huge power advances through the '70s. Braced swingarms were a go-fast item, just like aftermarket exhausts. Superbike racing was becoming a thing, with legends like Fast Eddie Lawson riding these race-modified bucking broncos like so:

View attachment 70395
Braced swingarms, Kerker exhausts, modified airboxes, Stage III jet kits, porting and polishing, tampons in the sump, all were part of the scene that bikes like the Zed-Rex is trying to recapture. All of it infinitely cooler to me than the Bonnevilles, cafe racers, black leather jackets and Brylcreem scene, or the various other nostalgia trips that have gripped biking over the years...

Modern swingarms can be similarly braced, but in a much more complex way:

View attachment 70397
Click to expand...
Thanks for the detailed info. Very interesting stuff and I had a dual Kerker exhaust on my '86 VFR750 which absolutely howled.

Good Luck with the Griso!
 
The swingarms on those '70s bikes weren't strong enough for the big motors (neither were the frames, but that's another discussion) so CalFab whipped up these trussed swingers... which just moved the excessive forces to the swingarm pivot, so they started bracing that too, which moved the forces to the steering head... and we got aluminum extruded frames.
A buddy used to wrench for Lang Hindle when Lang was at the top, and the things they did to that bike to make it turn was hilarious.
Modern thinking says a moly swingarm is better than aluminum, you can make it almost as strong for the same mass but a steel swinger will spring back to shape faster than aluminum... it will flex a little bit more, but snap back to shape a LOT faster
A KZ or GS at speed is still pretty scary, even today. A GS or KZ weighs about the same as a CBx and is only about 2" narrower. That's a LOT of bike to get turned.
CalFab is making swingarms again.
 
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