I sccessfully reduced the trail on my Honda GL650 2 inches by switching to some Honda Magna forks. The Magna forks have the axel mounted ahead of the fork sliders. The improvement is subtle, but definitly an improvement. It takes less effort to steer. The low speed wobble is still there, but easier to control. When the front tire gets thrown around in the ruts, it is easier to keep going in the direction I choose. If a 2 inch reduction is good, perhaps more reduction will be better. I don't have a thousand bucks to throw at a modified triple tree, but I do have a welding shop. What exactly are the pros doing to change the triple trees to reduce the trail? Cut and weld, heat and bend, or both?
Cut, weld fill, rebore at a different rake angle.
So what exactly is this different rake angle?
Being new to this, I would hate to modify my own triple tree on the Valk. As far as I can tell, there is only one mfr that does this and that would leave me with an out of production bike with no way to sell it as a two wheeler againunless I would find another stock triple tree. As for the costs of redoing a triple tree, I won't talk about it.
The one company that does this talks about 4.5 degree. It would make more sense to me to speak in terms of how much the trail is reduced. That should be the standard.
To sum it up, I'm not happy with the options, They are all expensive!
Originally written by solo1 on 10/30/2006 5:17 AM
Being new to this, I would hate to modify my own triple tree on the Valk. As far as I can tell, there is only one mfr that does this and that would leave me with an out of production bike with no way to sell it as a two wheeler againunless I would find another stock triple tree. As for the costs of redoing a triple tree, I won't talk about it.
The one company that does this talks about 4.5 degree. It would make more sense to me to speak in terms of how much the trail is reduced. That should be the standard.
To sum it up, I'm not happy with the options, They are all expensive!
I agree, all of the options seem expensive. Also, I do some welding in my shop but mainly for non-structural items on my motorcycle and other projects. Having seem what happens when triple trees break on a motorcycle, I would not want any welding done on the triple trees on any bike that I ride.
So, if I were to change to a different triple tree for a motorcyle-sidecar rig, forgetting the cost for a moment, I would only want a new unit, not a modified, welded one.
Yes, I'm an OK welder. I do TIG, Stick, MIG and Gas and have for many years. Still, even though I know how to weld, I would still want a one-piece deal on the front of the bike, no welding. There's just too much riding on it. No pun intended.
My unsolicited .02
I am comfortable with heating and bending the lower clamps of the triple tree. Moving the upper clamps on the triple tree is where I get nervous. Cutting and welding is my last choice. Fabricating a new upper clamp sounds better (safer) to me.
Perhaps building a leading link system would be more cost effective and alleviate some anxiety abould the triple tree issues. Anyone with experience on that avenue?
Your also going to need a very accurate jig to hold the triple trees and your drill- any small inaccuracies will be magnafied by the length of the forks!
I do a lot of jigging in my business. Jigging is a forgone conclusion. It is the actual angle and structural integrity that concerns me. I don't want any surprises when I'm done. I'd like to get it right the first time.
If you have copies of Kendall's books there are some pretty comprehensive notes and illustrations handling rake and trail. You might peruse them for trail numbers.
Lonnie
GNM109 (I agree, all of the options seem expensive. Also, I do some welding in my shop but mainly for non-structural items on my motorcycle and other projects. Having seem what happens when triple trees break on a motorcycle, I would not want any welding done on the triple trees on any bike that I ride)
I am concerned. I had Steerite in Canada modify the triple trees for our Yamaha Venture Royale. You stated you have see what happens when triple trees break on a motorcycle. Were these mishaps on modified sidecar tugs? Do you have any pictures or website or engineering accounts of those occurrences? I would hate to see that happen to our bike. The proprietor of Steerite is reputed to have spent years in the sidecar engineering and design field and he never said anything about their re-machining and re-welding breaking.
If you could provide documentation I could inform Steerite.
Thanks!
Bruce
Originally written by Hack'n on 10/30/2006 12:58 PM
If you have copies of Kendall's books there are some pretty comprehensive notes and illustrations handling rake and trail. You might peruse them for trail numbers.
Lonnie
This is a good start. In fact I do not really know what the degree figures advertised by the ones who market the modified triple trees really refer to. Can someoen explain this?
Easy steering is related to reducing the trail on any bike when talking about tree mods or leading links. What trail is the final product? It isn't usually given in the ads.
We can reduce trail soem by other means. Changing out the forks can sometimes work well. The XS1100 Yamahas for instance came in a standard version and a cruiser type version. The latter had the front axle in front of the centerline of the fork tube. By putting those forks on the standard trail is reduced. The BMW k bikes had the axle behind the center of the fork tube slightly. Some have reversed the forks to reduce trail (swapped left for right )These type of things might be able to be done on other bikes as well as mentioned in a previous post.
A smaller diameter front wheel 'ASSEMBLY' can reduce trail.We are talikng about decreasing the rolling diameter of the front tire here.
Running the front forks up through the triple trees can reduce trail. You must be carful as going to far can cause clearance problems when bumps are hit due to suspension travel.
Raising the rear of the bike reduces the rake of the steering head slightly which also reduces trail.
Wider handle bars will give more leverage to ease steering too.
Bar backs will also give more leverage.
Some saythey have run a leading link and didn't like it because there was no 'feel' in the steering. That only means that the trail was reduced farther than it probably should have been for them. Some can tolerate less trail than others and be happy with it.
We see these degree figures all the time but how they actually relate to final trail seems a mystry. If it means that the angle of the holes in the triple trees are change by 'x' amount of degrees on all trees then it means that the final trail figures on one bike will be diferent than on another brand bike. rake angle comes into play and how it relates to the initial trail figures.
Originally written by Bhaebe on 10/31/2006 1:38 AM
GNM109 (I agree, all of the options seem expensive. Also, I do some welding in my shop but mainly for non-structural items on my motorcycle and other projects. Having seem what happens when triple trees break on a motorcycle, I would not want any welding done on the triple trees on any bike that I ride)
I am concerned. I had Steerite in Canada modify the triple trees for our Yamaha Venture Royale. You stated you have see what happens when triple trees break on a motorcycle. Were these mishaps on modified sidecar tugs? Do you have any pictures or website or engineering accounts of those occurrences? I would hate to see that happen to our bike. The proprietor of Steerite is reputed to have spent years in the sidecar engineering and design field and he never said anything about their re-machining and re-welding breaking.
If you could provide documentation I could inform Steerite.
Thanks!
Bruce
No. I have no documentation. I have seen triple trees break in enduros, on Scrambles tracks and in Hare and Hound races in my past. Often years back, people would modify a street bike like a Matchless 500 or an AJS. These had alloy top crowns on the triple trees which were prone to crack and dump the rider when subjected to the strain of racing and off-road competition. Once tt happened to a fellow who was just ahead of me on a dirt road on a Matchless. Predictably, he fell and got cuts, bruises and rash. It would have been worse in traffic, i'd bet.
I just don't think it's a good idea to go welding on frame or fork parts. Knowing how to weld is different from knowing what to weld.
Some of the triple trees that are built for the purpose out of one piece of metal, like hard aluminum alloy or steel would probably be fine. I just don't like modifications on critical parts.
Mark,
I hear from a reliable source that the late model Harley ElectraGlides have about a 4.5 degree fork rake stock. Raked trees for these are usually 3 to 5 degrees. If 5 degree trees are used that would put the fork rake at 9.5 degrees which would be added to the steering head angle for the total front end rake. Different models of Harley have different original fork angles as do the other Mfg'rs so total rake will vary.
There is no one panacea for plotting what angle is needed for all bikes or combos. So, back to the (HAL'S) books. Some geometry is needed to plot the existing trail. You will need a detailed illustration (or the actual bike) for this. Wheel and tire sizes, frame attitude, existing steering head rake, come into play here.
Then the question arises of how much is too much? Too much reduction of trail will produce an evil handling rig. Perhaps an uncontrollable one.
Some say 2 inches is good some say 2.5 is good. Do you know which is right for your particular needs? Do you have a working example to follow?
If not, the odds of getting it right the first time are heavily against you.
Good luck,
Lonnie
Lonnie,
Thanks, this has all been good information. Doing an actual drawing of my rigs geometry would be a good place to start. I've been riding it with the new forks for a few days and am quite happy with the improvement. More may be better, but the next step would take the bike out of action longer than I am willing to tolerate. I'd rather ride it than work on it. I will research this over the course of this coming winter. Thanks to all for the input.
It's warmed up to 35 degrees, I think I'll go for a ride.
Wider bars help too Mark.
19F here this morning. 48F now, think I'll wash some rigs to cool off.
lol,
Lonnie
