More modern cartridge fork options - retaining GS wheels & proper/revised geometry

[John Kat]

I don't know if it's wisdom or not but I would go with the most brakes I could get and then worry about learning to not lock them up. If you can't lock your wheel you don't have nearly enough braking power. And I never use more than 2 fingers. If it takes more than that something is wrong and needs fixing.


Mark

I agree with Mark, go with the best calipers and M/C available for your bike.
The difference is not related to the capability of locking the front wheel but to the control you have on your braking power BEFORE locking up the front wheel.
My modern KTM 1290 R comes with the latest Brembo gear and it's amazing when you are braking real hard that you can modulate the last percent of braking power in total control.
My GS 1000 S fitted with GSXR 1100 first gen fork and calipers improved a lot when I fitted a Nissin Radial M/C.

[John Kat]

Has anyone so far tried the Vstrom 1000 triples?
What's the spacing between the fork tubes ( center to center)?
Ideally it should be 205 mm to take eitheir a complete GSXR 11K or R6 front end.
Well, I got the info today...it's 205 mm!!!
This means that thanks to the research done through this thread we now have a good solution for a modern cartridge type fork for the GS 1000 WITH the correct geometry.
I personally prefer the R6 fork over the GSXR 11K given that it's 753 mm long versus 740 mm and that the R6 calipers are far superior to the GSXR's.

[Chuck78]

I'm looking into this again, as I'm looking into wheel and fork combinations for a spare 750 titled frame build that I have (870cc, VTR1000 Superhawk forks or CBR600F4 forks), and my GS550 corner carver build.
I'm trying to get Bores Cycle Salvage to measure an 01-06-ish VSTROM DL1000 steering stem to see if that will work on a GS frame with any shimming to the lower bearimg or the upper race. If so, that and some RF900R or CBR600F4 forks would work great with a 3.00/3.50x17 GS1150 rear and 130/90-17 or 140/80-17 rear tire, and an 83-84 VF750C/VF1100C Honda wheel in 18x2.50 (looks like GS star mag, 296mm Shadow 600 rotors will fit, need to look into 310mm rotors if RF900R forks).
The VF1000F Interceptor or 91(93?)-07 CB750 Nighthawk steering stems will be useable (potentially too tall), then the superhawk forks would work well with a 17" front wheel off of a Zephyr 550 and a 110/80-17.
The Zephyr triples may be a candidate as well but i have not looked into stem height.

[bobgroger]

I'm looking into this again, as I'm looking into wheel and fork combinations for a spare 750 titled frame build that I have (870cc, VTR1000 Superhawk forks or CBR600F4 forks), and my GS550 corner carver build.
I'm trying to get Bores Cycle Salvage to measure an 01-06-ish VSTROM DL1000 steering stem to see if that will work on a GS frame with any shimming to the lower bearimg or the upper race. If so, that and some RF900R or CBR600F4 forks would work great with a 3.00/3.50x17 GS1150 rear and 130/90-17 or 140/80-17 rear tire, and an 83-84 VF750C/VF1100C Honda wheel in 18x2.50 (looks like GS star mag, 296mm Shadow 600 rotors will fit, need to look into 310mm rotors if RF900R forks).
The VF1000F Interceptor or 91(93?)-07 CB750 Nighthawk steering stems will be useable (potentially too tall), then the superhawk forks would work well with a 17" front wheel off of a Zephyr 550 and a 110/80-17.
The Zephyr triples may be a candidate as well but i have not looked into stem height.

The RF900R stem and triples will work with no modifications. If you want to use handlebars the Bandit upper fits with the addition of a hardware store bushing. IIRC the forks are considerably shorter.

[salty_monk]

Honda Blackbird Rotors are 310mm & have the same offset as the CBR Rotors (around 16mm). The Hyabusa rotors are 5 bolt & don't have much offset.

The issue you will have using a 4 or 6 pot caliper with the standard wheels is space between the caliper & the wheel. You will have to space the rotor out quite a bit to get clearance & then the issue becomes the speedo drive.

It should be possible (as long as you're using a wider fork) but you'll have to look at the clearances carefully.

One thing you may want to look at is using the 16" wheel from the 1150 - they have a wider hub.

I used the GSXR 6 Pot calipers on my GS750ES with a GSXR1100 fork and a 17" wheel. They worked great. I bought them only as they were cheap on Craigslist locally. A lot of the GSXR guys take them off & run the 4 pots as they say better feel with no loss of power (not sure I believe that as the swept volume of the 6 pots is greater - however it may not be real world usable extra power...).
IMG_3544.jpg

[John Kat]

I'm looking into this again, as I'm looking into wheel and fork combinations for a spare 750 titled frame build that I have (870cc, VTR1000 Superhawk forks or CBR600F4 forks), and my GS550 corner carver build.
I'm trying to get Bores Cycle Salvage to measure an 01-06-ish VSTROM DL1000 steering stem to see if that will work on a GS frame with any shimming to the lower bearimg or the upper race. If so, that and some RF900R or CBR600F4 forks would work great with a 3.00/3.50x17 GS1150 rear and 130/90-17 or 140/80-17 rear tire, and an 83-84 VF750C/VF1100C Honda wheel in 18x2.50 (looks like GS star mag, 296mm Shadow 600 rotors will fit, need to look into 310mm rotors if RF900R forks).
The VF1000F Interceptor or 91(93?)-07 CB750 Nighthawk steering stems will be useable (potentially too tall), then the superhawk forks would work well with a 17" front wheel off of a Zephyr 550 and a 110/80-17.
The Zephyr triples may be a candidate as well but i have not looked into stem height.

I bought a DL 1000 VStrom triple that I pulled apart.
I will measure the spacing between the bearing landings for you tomorrow.
Do you have the measurements of what will work?
I didn't want to dismantle one of my bikes to measure....

[Chuck78]

I bought a DL 1000 VStrom triple that I pulled apart.
I will measure the spacing between the bearing landings for you tomorrow.
Do you have the measurements of what will work?
I didn't want to dismantle one of my bikes to measure....

What year of Vstrom triple?
Looking at the eBay listings, I later realized that there are two different types of RSU/ conventional fork steering stems. One looks like the GSXR Hayabusa stems that I have here, 30 mm upper and lower bearing area, and all aluminum clear anodized stem. If it is the same height as that, it can be made to work with little shimming adjustment.

[limeex2]

Here's a front end assy off of a 95-97 Triumph Sprint 900 I have as a parts bike. Other than 1 shim under the steering stem nut, it bolted right up. There are 3 different heights of clip-on style bars off of different models that will fit and 1" spacers are available too. 95's have no adjustments. My 97 every day driver is fully adjustable and will get swapped into this build. 95's with Gold Valves/springs are beautiful riding. Brakes w/EBC HH pads and S/S lines are true 2 finger braking.

[Chuck78]

Lime,thanks for sharing. Is that GS1000?


I'm generally not so much a fan of futuristic looking modern wheels like that, hence the topic of this thread and the emphasis on taller forks and triple clamps with proper offset for frames with 27 degree rake and 19" or 18" front wheels.
I do make an exception for some wheels such as early Honda CBR wheels.



The CBR600F3 wheels are fantastic looking in a semi-retro way, and can run a 160/60-17 and 120/70-17 sticky hypersport type radial tire, but still look generally like an old school 6 (or 8, etc) spoke mag wheel. I think that mixing a vintage bike with a futuristic looking modern wheel is a bit odd and I'm not very attracted to it. and this thread I devoted to fork upgrades to modern cartridge systems while still retaining proper geometry and not ADDING any amount of trail to our steering geometry. Most of these modern sport machines have 25, 24.5, 24, and even now 23.5 degree head tube rakes on the frames. Thus the modern triple clamps that were originally paired with the forks have very little offset to make for proper trail geometry spec on the intended frames. On our flexy vintage frames, we are dealing with 2.5 or 3 degrees more rake than what was intended for with the minimal offset triple clamps, so we are going to be adding a modern looking fork and wheel with no real benefit other than better damping and braking, as the trail will still remain in the same vicinity as stock (somewhat slow steering). It gets reduced significantly by dropping from a tall 19" tire to a low profile 17" tire, but then increased right back again by attaching this fork/wheel to the bike with a triple clamp set that has very minimal offset (generating a significant amount more of trail).
Proper selection of triple clamp offset is very critical when you are desiring a bike which handles in a very sporty and fun manor. That is why I was very interested in that ~01-'06 VSTROM DL1000 triple clamp... It looked to have the same GSXR/Haybusa stem that I have two of here, which could be adapted to a GS frame with the right bearings and spacers, and it looked to be approximately 42mm offset from stem to centerline between the fork tubes. This would work out really well without having to drop the front end to the ground in order to reduce rake in order to reduce the excess trail spec.

More front tire diameter, or less triple clamp offset, or more relaxed steering rake (shorter "lowering" shocks), or any of these together or seperate = more trail = slower steering = less sporty feeling = more stability at high speed.
Less front tire diameter, more triple clamp offset, or more frame head tube rake = less trail = faster steering = more sporty feel

If going 17" wheels, it is really a good idea to go at least 25mm longer on the rear shocks, so that you can gain back a slight bit of cornering clearance lost by dropping the front a few inches. Our bikes with stock wheel sizes can't really lean over to the edge of the tire tread (even on a tire properly sized for the rim width), and dropping the front end over 2" and the rear around 1" will mean stator cover and footpegs are going to rub much sooner in hard leans, limiting the cornering potential of our GS's.


Angle milled and TIG welded stator covers can be made to get some of that clearance back, but it's always a compromise going down to 17" on that regard.

Lots more could be said about the pros and cons of each side of the story with these upgrades and their compromises, but I'll leave it at that for now while I go browse for Suzuki Samurai / '78-'91 Chevy LUV truck / '79-'83 Toyota short bed pickup truck 4x4's...

[John Kat]

What year of Vstrom triple?
Looking at the eBay listings, I later realized that there are two different types of RSU/ conventional fork steering stems. One looks like the GSXR Hayabusa stems that I have here, 30 mm upper and lower bearing area, and all aluminum clear anodized stem. If it is the same height as that, it can be made to work with little shimming adjustment.

I believe I have the early Vstrom triples with removable handlebar fittings.
The bearing areas are both 30 mm in diameter as you stated however the bottom is slightly larger requiring a force fitting.
The bottom landing is 22.5 mm long while the top is 16 mm long.
The inner distance between the two landings is 151 mm.
Here's a picture:

IMG_1134.jpg

[John Kat]

And here is the top triple:

IMG_0755.jpg

[John Kat]

Good news, the DL 1000 Vstrom triples should fit our GS 1000s without modifying the stem!
I measured the distance between the bearing landings on a first gen GSXR 1100 frame ( that's identical to our GS 1000s) and it comes out at 153 mm.
As the inner and outer races of the bearings are in the same plane (on the side of interest), the 151 mm measured between the bearing landings on the stem provide a margin of 2 mm.
As the bottom bearing is 17 mm high there is a space of 5 mm below it that must be filled with eitheir a spacer and/or the bottom seal.

[Chuck78]

AWESOME, THANKS JOHN!

I suspected this was the case going off of the triple that I had here with the same looking stem. And it did look like there was quite a bit of room to space the triple up and down on the bearings and head tube of the frame. This is most excellent news. I was going to buy one of these myself just to measure it, as I see some on eBay for $13 just for the lower. I suspected this was the case going off of the GSXR & Hayabusa triples that I had here with the what appeared to be the same stem. And it did look like there was quite a bit of room to take the triple up and down on the bearings and head to above the frame. This is most excellent news. I was going to buy one of these myself just to measure it, as I see some on eBay for $13 just for the lower.

This triple sounds like it will be the ticket then for getting quicker steering on Fork conversions without much hassle.
Running a GS with a 17" set of wheels and this triple, in CBR 600 F4 or F4i forks, Bandit 1200 Forks, 1989 GSXR 1100 K Forks, or for the smaller bikes with shorter forks, 1989 GSXR 750 forks, and I believe 1990 is the same on the 750. RF900R forks are the same as Bandit except the 1997 models, the last year, had adjustable damping, but they are very short, even shorter than the CBR 600 F4 forks, which are about the minimum Fork blank that you would want to run on the bigger bikes, and that will drop a front a good bit even. The RF forks would work great on a twin but the springs are a bit stiff for a lightweight twin, but may work well for a GS 550 or 650 with a 4 into 2 exhaust.


This is most excellent news because this gives bikes a reduction in trail to make it much more sporty feeling than the stock specs! I was befuddled quite often with people who would run a near stock frame rake with 17 inch wheels and very minimal offset triple from their modern fork swap, as it would not improve on the steering whatsoever, and kill the ground clearance.

Thanks a lot, John!

FYI AllBalls has 5 mm lower bearing spacers that they have shipped me with kits before, so this is very readily available in very doable.

[John Kat]

AWESOME, THANKS JOHN!

I suspected this was the case going off of the triple that I had here with the same looking stem. And it did look like there was quite a bit of room to space the triple up and down on the bearings and head tube of the frame. This is most excellent news. I was going to buy one of these myself just to measure it, as I see some on eBay for $13 just for the lower. I suspected this was the case going off of the GSXR & Hayabusa triples that I had here with the what appeared to be the same stem. And it did look like there was quite a bit of room to take the triple up and down on the bearings and head to above the frame. This is most excellent news. I was going to buy one of these myself just to measure it, as I see some on eBay for $13 just for the lower.

This triple sounds like it will be the ticket then for getting quicker steering on Fork conversions without much hassle.
Running a GS with a 17" set of wheels and this triple, in CBR 600 F4 or F4i forks, Bandit 1200 Forks, 1989 GSXR 1100 K Forks, or for the smaller bikes with shorter forks, 1989 GSXR 750 forks, and I believe 1990 is the same on the 750. RF900R forks are the same as Bandit except the 1997 models, the last year, had adjustable damping, but they are very short, even shorter than the CBR 600 F4 forks, which are about the minimum Fork blank that you would want to run on the bigger bikes, and that will drop a front a good bit even. The RF forks would work great on a twin but the springs are a bit stiff for a lightweight twin, but may work well for a GS 550 or 650 with a 4 into 2 exhaust.


This is most excellent news because this gives bikes a reduction in trail to make it much more sporty feeling than the stock specs! I was befuddled quite often with people who would run a near stock frame rake with 17 inch wheels and very minimal offset triple from their modern fork swap, as it would not improve on the steering whatsoever, and kill the ground clearance.

Thanks a lot, John!

FYI AllBalls has 5 mm lower bearing spacers that they have shipped me with kits before, so this is very readily available in very doable.

Hi Chuck, I'm glad I was able to help!
In fact I believe that it's because I saw your mention of the Vstrom triples that I got going.
Like you, I've been wanting to quicken the steering on our old bikes.
You maybe saw this thread I started a while back:

https://www.thegsresources.com/_forum/showthread.php?206668-A-modern-fork-upgrade-for-17-18-and-19-quot-wheels/page2

Post N°25 shows my GS 1000 ST with the OEM 19" wheel attached to a GSXR 11K fork.
The slowest steering you can come up with for sure!
BTW, the the trail and caster are not the only parameters that affect the steering response.
I recently tried a 2018 Triumph Speed Triple R and the steering felt rather heavy at low speeds despite a drastic geometry.
Maybe it's due to the weight distribution towards the front?
Great I could help you on this subject!
John

[Chuck78]

John, did you have any drawings that you had posted previously for those 15 mm to 20 mm axle adapters?

Did you ever figure out why the first GSXR 1100 K Fork was so stiff? You said you swap the fork tubes. I wasn't sure if you just meant the Chrome upper tubes, or the entire fork leg assemblies. You also mentioned some different oil viscosities. Have you just put too stiff of oil into it? 2.5 weight was best? In Bel-Ray?
How did the GSXR 1100 K Forks compared to the Bandit damping?

Those two forks get the vote for me because they look almost exactly like a GS Fork, whereas they very awesome performing CBR 600 F4 Fork has the modern style caliper mounts with the lower projecting rearward an inch-and-a-half further. This is probably not a big deal at all, but I like the fact that the first two that I mentioned look very much like a GS Fork.

Thanks!

Chuck