Triple tree stem lengths? Front end swap issues

Just for perspective here's a couple of xs750 triples showing the difference between standard and forward leading........
This is a standard
http://www.ebay.com/itm/1976-Yamaha...ash=item4165a8c2d4:g:ss0AAOSwv0tVbOhu&vxp=mtr
This is forward leading
http://www.ebay.com/itm/1979-Yamaha...ash=item4165a8c37a:g:bC4AAOSwNSxVbOhu&vxp=mtr

Taken off eBay so check 'em out while they're still up.

 

nj I don't think most stock triples have a "lean" or angle between stem and tubes, AFAIK all stock triples have parallel stems and tubes, the offset certainly does change, as you say bikes with forward axle lowers tend to have less offset in the triples, The only "offset or angled triples I know of are aftermarket for Harley choppers and some dirt track forks.

 

Right G, all parallel. Proper term is offset, gotcha. Keep me straight, I'm getting old. CRS.

Looking at pics of the zzr's on eBay it appears the offset is the same as the forward leading triple axles, and the pics at the beginning of this thread show non leading forks on what I assume are zzr triples.
So
The same result of stance, if the zzr's and the xs750 leading axle triples are the same offset, could be gained with a set of xs750 leading axle triples-swapping stems with the xs650- and adding a set of Standard xs750 forks, 36mm diameter.

Think I'll go out and play with the chickens now............

 

Sorry nj not trying to beat you up.

It appears the ZZR fork he is using is a conventional axle inline with the tube design.



The Axle forward was mostly used on cruisers and dirt bikes. As mentioned for the long look on the cruisers and long suspension travel on dirt bikes.

It appears the ZZR triples have quite a bit less offset than the XS units.





I think it should be possible to get some risers bolted on the the ZZR top triple you have.
I would suggest you do NOT attempt to find "some other triple" This will almost be guaranteed to be a path littered with part$ that will not fit. My suggestion would to find a set of risers and bars you like and find a machine/custom shop to drill / fit them to the ZZR top triple.


This is critical stuff, getting the fork action right can be life or death. reducing off set can "quicken" steering action, making head shake and other not nice handling quirks more likely. The late model XS steering geometry is rather conservative and can take a bit of jiggering without becoming a monster but tread lightly here.

There is a lot of info out there on fork design and how offset, trail, rake, all affect handling, it's a deep subject, ANY geometry changes should be approached with caution. Check fork handle bar to gas tank clearance at steering lock also.

Gary's oft repeated mantra; If you ever get a speed wobble going; push FORWARD on both grips, your arms will then act as dampers and help stop the wobble. If you pull back on the bars attempting to stop a fork oscillation, your body mechanics will act to INCREASE the wobble, weave with bad results.

 

I have been following this thread with interest as I too am in the process of putting together information and parts for a front end swap.

My research has yielded different information than what is listed below. Please do not take offense Gary as I am not questioning your expertise at all. Obviously well respected on this forum. Just want to make sure I fully understand it as well.

All things being equal, meaning all other figures stay the same (rake, wheel diameter, fork length, etc), doesn't reducing the triple offset increase the trail? Increasing the trail makes the steering vague, or slower acting more like a cruiser. We would essentially be moving the forks closer to the steering stem, moving the wheel back, increasing the distance from where the wheel contacts the earth from where the axis of the steering stem would contact the earth.

We all know that when it comes to a front end swap, all things are not equal. All those figures above change even with a simple change and caution needs to be heeded.

Info from these sites (as well as others):
http://www.motorcycle-superstore.com/4125/mngr/rake-and-trail-explained.aspx
http://www.cycleworld.com/2015/05/2...icks-understanding-motorcycle-rake-and-trail/

Trail-Rake Calculator:
https://www.rbracing-rsr.com/rakeandtrail.html

 

No offense taken at all! I have no fork design expertise, my comment is/was seat of the pants intuitive and I welcome anyone that can unravel the mysteries to straighten me out,

 

I believe that would be the way to go. It's hard enough trying to get a new front end to work on a different bike. I think adding a top clamp from an entirely different 3rd bike would open up a huge can of worms.

My fork design experience is in research only. My original plan to cafe my bike fell apart when I encountered frame issues. I did acquire a very nicely priced, very nice front end (forks and triples) from a 1980 XS1100G. That's the standard, not the axle leading special. Triple offset is less than the 650 but haven't measured to know exact measurements. I wouldn't be able to accurately measure trail until I had the rolling chassis put together though.

Just trying to learn as I go, and listen to those that have gone before me.

 

SkavenDC Quick look around sure says you are right about reduced offset longer trail more "stable" steering. Was kinda riffing sport bikes often have less offset therefore less is quicker. But perhaps it's more of a compensation for steeper sportbike neck rake??

Tradition and fashion enter into the manufacturer's design tradeoffs also.

 

That was my finding as well. Narrow offset coupled with a steeper rake yielded quick, sport bike steering.

Found this on another site.

The relationship between rake, trail and offset

If you increase the rake, the trail increases​

If you increase the trail, the rake increases​

If you increase the offset for both yokes then the trail decreases​

If you increase the offset for only the top yoke/ triple tree then the trail will increase​

If you increase the offset for the bottom yoke/ triple tree independently then the trail will decrease​

Can't find it now, but also found some very interest information regarding raking a chopper and why they have raked triples and not just rake the neck. Basically, splitting the difference between the neck and the triples provided a more stable bike.

 

That's good, SkavenDC. I'm glad that info on raked front ends and steering geometry is out there for folks to see. Back in the day, there was a short-lived company that marketed an "easy rake" set of trees, that would get you the chopper 'look' without the fuss-and-muss of actually raking the neck. Turned out that setup gave you a negative trail, and reversed the bike's natural ability to upright itself. You had to conscientiously steer to keep it upright. Very strange to ride. Very dangerous...

 

2M they still sell that stuff! Maybe not quite as extreme as "back in the day" products, Google raked triple!

 

Okay. Looks like wiser minds have prevailed, and there's boatloads of info on using these to properly manage trail dimensions. The early years' new/homebrewed/experimental/unproven stuff was sometimes pretty freaky, and you had to really watch what would come rolling into the shop.

This thing kinda looks like those early nightmares, but this one uses an innovative lower bearing offset adapter to bring rake/trail back to reason.

http://www.seegercycle.com/sportster-narrow-glide-chopper-kit.aspx

 

Hi all, I have an XS1100 fork. A standard, 36 mm tubes. Not the leading axle.
I have not put it on the 75 yet. I need to swap stems around and try it. The difference in offset has me wondering how it will effect handling. Won't know till I get the stems swapped.
I have not been feeling well for a while so haven't been doing as much with the bikes as I wanted. With the doctors help I should be back into shape soon and will get back into the bike experimenting.
Leo

 

Based on my research, if the front end swap does not change any other figure, a smaller offset should increase trail over what you have now, making the steering "slower" than what you have now. More like a cruiser.

Any change made has the ability to alter the stance. Longer forks or bigger diameter wheel (or a combo of both) would rotate the entire bike at the rear axle, altering the rake. Shorter forks and smaller wheel has the opposite effect. Changing fork length, wheel size, triple offset and rake will affect trail in so many ways.

Too much trail will cause the bike to feel heavy and sluggish.

Too little trail will lead to instabilities at higher speeds (aka - wobble).

Here is an advanced calculator to those interested that factors in wheelbase and rear tire size.
https://www.rbracing-rsr.com/advchoppercalc.html

Also, you may find that those XS1100 forks are 37mm. Mine are, and I thought all of them were, but I may be wrong on that.

 

Not sure about all the geometry, but I found a 86 Radian that just blew the motor out. Paid $200 for the whole thing with title, took the entire back end and front end off including tires, going to add it to my XS frame and motor. Had the steering stem off the XS pressed out and installed in YX (Radian). Should be different anyway. Fatter front tire and thicker forks. Just wanted a different look. Only change so far is the rear sprocket on the Radian 45 v 34 on XS. Ordered a new sprocket and I am in business. All that fuss about axle diameter and length is not needed as I had all the parts! Sold the blown motor and XS swingarm and two crappy wheels/tires with title for $300 to Ebay guy!!