Avoiding Triple-Clamps for Leading-Edge Axles?

[twist-throttle]

My '77 GS750B has 35mm forks with the axle underneath the forks, versus the leading edge of the forks.

I'm browsing similar era front-ends... particularly the 37mm from the 850, 1000 & 1100's...

Does anyone know if the leading edge fork that are often found on the L models... do their triple-clamps use a different Rake or Offset then the non-leading edge front-ends?

I do want to keep with the non-leading edge fork types... I want to keep the axle underneath the fork tubes.

If I go with 37mm triple-clamp from a bike that had leading-edge forks/axle... I presume that the geometry numbers will be different then my stock set-up.

What should I be looking for, or how do I distinguish which triple-clamp is which... say if the triple clamps are being sold by themselves without the forks.

Thanks for your time.

[Dave8338]

To the best of my knowledge...there is no offset in the trees themselves. There may be a greater rake in the neck/head stock...but the triples are straight inline with eachother. I sized this very question up when I was working on another project and looking for a front end (UJM) that had offset trees (in conjunction with my frame mods).
My 650 does not... Hope that helps.

In addition, If you're looking for more rake in the front end, I would suggest AGAINST offset trees, alone! Unless there is only a degree or two, you'll notice a significant amount of wheel flop in slow speed maneuvers (ie. parking lots and tight spaces). I've ridden a few HD's with offset trees and though the look is nice...they have a tendency "crappie flop" when you're rolling slow. .02 cents

[twist-throttle]

To the best of my knowledge...there is no offset in the trees themselves. There may be a greater rake in the neck/head stock...but the triples are straight inline with each other.

Sweet, this is exactly what I was hoping for, unless someone else disagrees with you...

No, no HD chopper action for me... I'm into the sport side of riding... so I am hoping to not reduce the handling of the bike at all.

After comparing the online micro fiche, it looks like the top clamp of the L models have a lower handlebar riser (which seems opposite of my expectations)... but if as you say, the actual offset is the same... I should be good to go either way, if I do end up installing this setup on my bike. Thanks

[Old Colt]

The offset of the triples between a straight and a leading axle are not the same.
I would recommend staying with the straight fork legs setup.
Running straight legs in a set of triples intended for leading axle will increase the trail making the steering heavy.
Doing the reverse will lighten the steering, probably to much so and may be on the verge of unstable. Nothing a good steering damper wouldn't hide though.

I am running GS1000 forks in my 79 GS550. What I did was bore the original triples from 35mm to 37mm and just slide the new forks in. Sweet and simple.
You can swap to the GS1000 triples if you want to space the fork legs wider to fit a 120-17 wheel and tire since the narrower 550-750 forks will be a bit tight with more than a 110 on a 3" wide rim.
Not an issue if you are staying with a 19" wheel.

If you swap to the 1000 triples you will need a different lower stem bearing.

Here are my 1K forks in the 550-750 triples. As you can see my upper has been blended to remove the bar mounts.

[twist-throttle]

Old Colt, wow... sweet mods to your 550 & thanks for the informative post.

I totally dig your riser-less top clamp & clip-ons... looks similar to my '08 GSXR 600... I've been thinking of putting clip-ons on my GS & was wondering about the risers sitting on the top clamp unused.
Looks like you won't be able to turn the bars much before hitting the tank... well that's like a modern sportbike as well... not being able to turn the bars very much. Did you weld up something different for steering stops to prevent the bars from hitting the tank, or no?

Also, I was wondering what was different with the front axle... I see that the micro fiche tell me a different part# between my 750 front axle & the 850, 1000, & 1100 use a different part#.
So the front-ends off of the bikes larger then the 750... their fork tubes are spread further apart??? That would be good for me, as I feel the narrow stock front-end looks a little week. Just my opinion though...

Hmmm, I just re-read your post... so you are still using your 550 triple-clamps... you just bored them out. I take it that you feel it's still safe, that there was only minimal material removed from the yokes... I suppose it would only be 1mm removed... as both sides will give the 2mm increase in fork tube diameter...

Man, I don't want to change the topic of this post, but as I browse your pic, what is that I'm seeing for rotors... are those Honda F3 rotors on it? I've read something about someone putting those on their original GS mag rims... what gives with your rotors that I'm seeing?

Once again, I really dig what you have going on with your GS, I'm sure the purist will be frowning... but that's ok

The offset of the triples between a straight and a leading axle are not the same.
I would recommend staying with the straight fork legs setup.
Running straight legs in a set of triples intended for leading axle will increase the trail making the steering heavy.
Doing the reverse will lighten the steering, probably to much so and may be on the verge of unstable. Nothing a good steering damper wouldn't hide though.

I am running GS1000 forks in my 79 GS550. What I did was bore the original triples from 35mm to 37mm and just slide the new forks in. Sweet and simple.
You can swap to the GS1000 triples if you want to space the fork legs wider to fit a 120-17 wheel and tire since the narrower 550-750 forks will be a bit tight with more than a 110 on a 3" wide rim.
Not an issue if you are staying with a 19" wheel.

If you swap to the 1000 triples you will need a different lower stem bearing.

Here are my 1K forks in the 550-750 triples. As you can see my upper has been blended to remove the bar mounts.

[Old Colt]

Umm, I have in the past needed to do K turns with a few of my bikes.
The steering stops are extended but more as a function of safety when road racing, It is done to reduce high siding.
The 750 tank has a fair amount of room for low bars compared to the 550 tank.
The 1K forks are spaced about 12mm wider than the 550-750 ones. I have a custom machined brace on the lower fork that does a very good job of tightening up the front end. It clamps on to the area where the boot would be and I run an internal mounted wiper from a 1983 550ES. I will try and get a pic up of this, it is a sweet setup.

The big bike axle is the same diameter but is longer with different spacers solely due to the 12mm wider spacing. Your original wheel, axle and brakes will go right on the 1K fork legs if they are in your trees.

And yes, Honda rotors, same bolt circle and fit right up with Bandit calipers. Minor bracket work for one bolt on the calipers and the rotors need there 6mm holes opened up for the 8mm bolts on the GS wheel. There are active threads for using the Kawi calipers on the forum.

I did my brake and fork swap 7 years ago so not every detail is fresh on my mind.


Here is a front view taken last month.



And here is a 17X3" mounted up with a trial fit of one late model disc.

[Old Colt]

Here is a picture of the fork brace I machined up for the bike.

[twist-throttle]

Old Colt: Thanks again for the informative post.
You say the larger bike's forks are spaced 12mm wider... well that's not very much I suppose... I mean it probably wouldn't make much of a visual difference.

Yep, I've read some of the kawi caliper mod posts... but I didn't have any facts about the F3 rotors... thanks for the heads up on that.

Your fork brace does look pretty trick!

Interesting build... this opens up some additional paths & ideas for my own bike.