39mm vs 49mm front end weight - Forty-Eight

[MODO SIKLER]

I've done days worth of research on this before I ended up burdening this membership with this.

2010 to 2015 Forty-Eight was equipped with 39mm stanchions on a "wide" front end.

2016 on, the Forty-Eight was fitted with 49mm stanchions on a "wide" front end.

I know it's a longshot ... but ... can anyone provide the observed weights (for comparison with one another)?

I'm interested in the 49mm set, but if it's going to add too much porkage I'll go another way.

Thanks for the help.

[84rzv500r]

i went from 39mm triple adjustable forks and triples to the XR1200X USD setup and anecdotally the USD bits felt about the same... where the improvements were:

20 year newer bits
better spring rate
Order of magnitude Stiffer - Fork harmonics gone + solid mount Bars nearly zero felt vibration in the bars and no more blurred mirrors..
3 deg less rake
Way better brake calipers + pad compound selection
Better tire selection=better braking
handling is quick but neutral - reacts pretty linear to counter steering inputs and stays where I put it with no tendency to turn in or stand up with a little trail braking...

[MODO SIKLER]

Originally Posted by 84rzv500r

i went from 39mm triple adjustable forks and triples to the XR1200X USD setup and anecdotally the USD bits felt about the same... where the improvements were:

20 year newer bits
better spring rate
Order of magnitude Stiffer - Fork harmonics gone + solid mount Bars nearly zero felt vibration in the bars and no more blurred mirrors..
3 deg less rake
Way better brake calipers + pad compound selection
Better tire selection=better braking
handling is quick but neutral - reacts pretty linear to counter steering inputs and stays where I put it with no tendency to turn in or stand up with a little trail braking...

I am coming off of Ducati 2valve air cooled stuff (1996 CR900), that bike is fitted stock with Showa USDs and "one finger stoppy front brakes" (not that I do any of that clowning around). So I'm hearing what you're saying about USD fork leg rigidity especially just beneath the lower edge of the bottom triple clamp which is a flex/vibration moment.

Only thing is that rig looks so ~meh~ in 2023 on a Sportster. Kinda like "who hasn't done that already?" type of thing, y'know? However I am open to discussing that idea. For sure ..

Would you say that some of the "quick but stable" handling characteristics are due to (perhaps) a small but significant reduction in trail rather than anything the ~USD~ rig is offering in that area of interest?

Is your front end from an XR1200? (EDIT: scratch this, I read your signature)

Are you running a 17inch front wheel? (EDIT: scratch this, I read your signature)

3 degree rake reduction ... achieved by the use of the XR1200 triple clamps?

Different aspect ratio (front tire) on the XR1200 front end you cooked up? (EDIT: scratch this, I read your signature)

What are the specs of your front tire? (EDIT: scratch this, I read your signature)


I'm nursing an idea that is a sortof nod to the early 1980s. In AMA Production racing back then there were some deeply important configuration discoveries made that (once refined) ended up influencing sport bike and even streetbike configurations from roughly 1990 to present day. I'll explain more about what I'm getting at later.

Hey, so thanks for the help so far! It's deeply appreciated.

[84rzv500r]

Originally Posted by MODO SIKLER

I am coming off of Ducati 2valve air cooled stuff (1996 CR900), that bike is fitted stock with Showa USDs and "one finger stoppy front brakes" (not that I do any of that clowning around). So I'm hearing what you're saying about USD fork leg rigidity especially just beneath the lower edge of the bottom triple clamp which is a flex/vibration moment.

Only thing is that rig looks so ~meh~ in 2023 on a Sportster. Kinda like "who hasn't done that already?" type of thing, y'know? However I am open to discussing that idea. For sure ..

Would you say that some of the "quick but stable" handling characteristics are due to (perhaps) a small but significant reduction in trail rather than anything the ~USD~ rig is offering in that area of interest?

Is your front end from an XR1200? (EDIT: scratch this, I read your signature)

Are you running a 17inch front wheel? (EDIT: scratch this, I read your signature)

3 degree rake reduction ... achieved by the use of the XR1200 triple clamps?

Different aspect ratio (front tire) on the XR1200 front end you cooked up? (EDIT: scratch this, I read your signature)

What are the specs of your front tire? (EDIT: scratch this, I read your signature)


I'm nursing an idea that is a sortof nod to the early 1980s. In AMA Production racing back then there were some deeply important configuration discoveries made that (once refined) ended up influencing sport bike and even streetbike configurations from roughly 1990 to present day. I'll explain more about what I'm getting at later.

Hey, so thanks for the help so far! It's deeply appreciated.

yep the XR1200 triples are -3... read Tony Foale on trail...

LOL I lived through that early 80's AMA/CCS, WERA, GP PRO, and later FUSA time... GPZ550, RZ350, FJ1100, FJ600, 87 FZR1000, 89 FZR1000, 90 FZR400, 92 Duc 900 SuperLight, AMHRA on 84RZV500R/R1 Hybrid..... did 2 years chasin the AMA BOTT as the wrench on a MG 1000 Lemans.. Quit in 2011.. also had a stint with go fast turn left from 69-75 AMA District 4..

[84rzv500r]

once you've gone USD lol you cant go back... the 84 RZV500R used the same clutch plates and countershaft sprockets as the 2002 R1 the production based two stroke made a little better torque on the dyno but was down maybe 25 HP on top from the R1 but 150 LBS lighter LOL ... front end ws bolt on... swingarm was a RZV/R6/R1 weld up piece... I had the hand welded alloy frame Japan Spec Bike i bought on the Grey Market.... no 17 digit VIN caused some issues... Harley and Yamaha are Parts Bin companies FWIW

[MODO SIKLER]

Really neat configuration you've worked up there.

Ducatis are another Parts Bin maker ("Monster").

I've read Foale years ago. I own his book (the first one) and the PDF of his as well. It's excellent stuff!

[hpotter]

test, please ignore