Questions about rake and trail

[Verismo]

This is a long way down the road, but at some point I'd like to upgrade the B's suspension. When I do so, rather than just swapping in tapered bearings, I was considering changing the whole triple tree to one with more rake. I emailed a fabricator who specializes in these for the sake of trike conversions. He said that they don't recommend increasing "just" the rake of the triple tree because it can cause instability at high speeds. I have to take him at his word for now because I don't understand the physics of this, so I thought I'd ask a few questions here to see if anyone can fill in a few blanks.

Now, I'm not tryng to turn the B into a chopper or anything ludicrous. But I owned a 99 Valkyrie and I really liked the way that bike felt. It had 32 degrees of rake and 6 inches of trail. The B has 29 degrees of rake and 4.5 inches of trail. Does anyone here have any experience with a change of this kind? It seems, to me, that this isn't a significant enough change by itself to cause worrisome stability issues, especially considering my style of riding. I don't really push the envelope or try to beat track records, or even push it very much in the twisties. I like to do that once in a blue moon just because the bike is capable, but I'm MUCH more interested in cruising around and enjoying the scenery.

I know what rake and trail look like, and how the numbers are derived, but I know very little about their applied physics, or suspensions in general, so I would appreciate ANY input any of you might have. Thanks for your time.

Jason

[Walcrow]

Jason...

The first person I would call is Max at Traxxion Dynamics. They fabricate a triple tree for the B and his business is suspension. With his recent videos on the new Wing and his new shocks for it, he obviously doesn't waste any time designing and manufacturing products asap. I would bet that if he thought it was feasible, he'd knock out a custom tree for you about as fast as you can spit....at a custom price though. Then, if he thought it would work, you might be the beta tester for the new tree and might could work at "deal" testing it out. He's got everything at his business to CNC that new tree for you. I'm curious if he's already considered it at some previous point.

[Verismo]

A second opinion from Traxxion is a great idea, Walcrow. Thank you.

Jason

[thumper 549]

What specifically are you trying to cure?

[jm21ddd15]

IMO, updating the suspension will be an improvement. However, changing the rake/trail, will most likely adversely affect the handling of a great handling "large" bike. Like thumper 549 said, "what are you trying to cure?"

[Verismo]

Thumper, I'm just trying to make the bike comfortable to cruise around on, plain and simple.

And Jm21, what specific adverse effects are you speaking of? My 1999 Valkyrie had 32+ degrees of factory rake on the same wheelbase and, to me, it handled just fine. It wasn't a corner carver, but frankly I didn't buy the F6b to set records in corners. It seems like it's happiest doing 80+ in a corner and holding a fantastic line, which is absolutely impressive, but that's not my style of riding for the most part. I want to be comfortable, and I'd be willing to give up some cornering ability for a more plush ride. Right now I'm just thinking out loud about the various approaches to this, and I appreciate your thoughts and ideas, as well.

Jason

[glryder98]

To achieve 32 degrees of rake with same wheel base as the F6B the Valk frame would have to be shorter. If you add more degrees of rake to the B you lengthen the wheel base and lengthen the trail. when you add rake to a motorcycle you lose handling and turning radius. remember back when choppers were all the rage you couldn't turn them around in the width of a street lane. The front wheel no longer turns but flops side to side which affects handling.

[jm21ddd15]

I'm all for the suspension upgrade. That, in itself, will give you a better ride. And, if your looking for a plush ride, definitely, change the OEM seat! Many good seats on the market, will make your ride more plush. The Traxxion system will also improve the handling in the corners, if your into that riding style.

[waynerock66]

Please pardon my ignorance but couldn't you just swap a triple tree from valk? I don't even pretend to know the answer but I've always thought that the F6B and the Valkerie were the same bike with differing amounts of plastic and electronics added to B. If this is not the case please educate me so I don't go around sounding like a dumbass. Lol.

[thumper 549]

After riding HD for the last 50 years I added this F6B to the stable-
Personally, I have no fault with the steering as it is pretty predictable.
Albeit it seems to have novocaine between me and the road.
It corners EZ, holds a straight line, no complaints.
My complaint is its lack of swing arm support as it will definitely wobble on the tar snakes, road humps etc.
I will guess it is because the lack of the swing arm on the other side to keep it all in purrfect alinement.

[olegoat345]

I don't understand the physics of rake, trail or none of that handling stuff either. I always figured the Mfg. (any Mfg. or bike) spend millions designing a given bike, they have the best minds and computers money can buy. I would suggest you really understand what's going to happen to the handling & ride, if you make these changes. If you don't like it, you're pretty well stuck with it. The other thing to think about is trade or sale value, if you're not happy with the changes. As a buyer, If I though it had been altered from OEM specs, I'd walk. As a seller, if you didn't disclose the changes, you could end up in court. === I've owned dozens of bikes, considering this bike is over 800# w/ 1800cc's of power, it's the best riding & handling bike I've ever owned. To me, it's like riding a big sport bike. Dat's my 2 cents worth.