View Single Post
Old April 4th, 2015, 08:26 AM   #63
InvisiBill
EX500 full of EX250 parts
 
InvisiBill's Avatar
 
Name: Bill
Location: Grand Rapids-ish, MI
Join Date: Jul 2012

Motorcycle(s): '18 Ninja 400 • '09 Ninja 500R (selling) • '98 VFR800 (project) • '85 Vulcan VN700 (sold)

Posts: A lot.
Blog Entries: 1
MOTM - Aug '15
Quote:
Originally Posted by Ghostt View Post
Good to know, makes sense that the fork springs are stiffer, just like the rear, so they match.
For loose definitions of "match".

According to RT's calc (which may or may not be perfectly accurate), the NewGen's fork springs are good for 95lb while the rear is good for 220lb. Assuming the PreGen's rear suspension is pretty similar to the 500's, its rear spring is good for ~180lb and the fork springs are good for <30lb according to RT. Likewise, the EX500 has fork springs for <30lb and a rear spring for 130lb. The '06-'11 EX650 is the opposite, with 320lb fork springs and a 140lb rear spring.

I understand that they can only sell a bike with one spring rate, probably aimed at an average rider. The springs may be too heavy or too light for your particular weight. But I cannot fathom why the front and rear would be so far off from each other. Rather than the spring rate just not matching the rider's weight all that well, they're causing "rocking horse effect" and other issues with the wildly mismatched spring rates. I had some interference with the SV650 shock on my bike at first, so I can personally attest that a too-stiff rear can make even a good front end feel really bad.


But yeah, according to the RT calc, the NewGen's fork springs should be good for a ~150lb rider on a PreGen. The EX500 springs are good for ~110lb. That's still way better (33% stiffer) than stock, but the NewGen springs are probably better for a lot of people. It would be nice to have someone verify 100% that the NewGen springs will work in the PreGen forks. The Gen1 springs are longer than Gen2, so they could also be cut down to raise the rate to around .70kg/mm (180lb PreGen rider) at 17" long. If you don't mind doing the mod work, the Gen1 springs' higher rate and length give you a pretty wide weight range that could be covered.
__________________________________________________

*** Unregistered, I'm not your mom and I'm not paying for your parts, so do whatever you want with your own bike. ***
InvisiBill is offline   Reply With Quote