OK...here is what I have learned....(thanks to my new friends on here). This is in reference to my 1996 FXDL

I have ran the numbers with rb's rake and trail calculator and by adding a 3 degree raked triple tree from accutronix, I end up with a trail of around 3.35 from a stock 5.8 on my 96 FXDL. I can't locate the actual figure, but by looking at the images of the Accutronix triple trees, the triple trees offset seems to be the least of the manufacturers I have been looking at.

Here is my question....

By adding the 3 degree triple tree kit and my trail ending up appro 3.35. How much will lowering the rear of the bike 1" increase it? I think I may be able to safely go from a 12.5" shock to an 11" progressive, but I'll worry about that after. I am just curious as to how much lowering the rear end an inch will increase my trail again?

You guys must get sick of these triple trees/ increased rake threads!! I do use the search feature first though....

 

I can't answer your question specifically, but I'll give what advice I have. When I changed my front end I mistakenly put a -2" on instead of stock. I quickly realized that I couldn't ride the bike. It was like riding that "whacky bike" at the fair that steers opposite... So my advice would be to be careful reducing the trail from the stock amounts. The factory specs are usually an "optimal" number such that anything less usually results in an undesirable setup. But, someone else may tell you otherwise.

Incidentally, I replaced the front end with a +2" and it rides like a dream...

 

good post, I can't answer specifically either. however, I lowered my front 1" and 1 1/2" in rear both progressive setups. I'll keep an eye on this one -maybe I can learn sumthin?

ohhh- and lets see some pics when your done! [sm=smiley20.gif]

 

My understanding is that lowering the rear will increasethe trail. Raked trees lower the trail. Raked bearing cups increase the trail. I believe stock trail is somewhere around 5 something.

 

hunter, when you say "lowering the rear end an inch",

I assume you are speaking of shorter shocks,
not smaller diameter rear wheel.

shorter shocks lowers the seat,
no change to trail geometry.

This does lower your center of gravity.
Myownself, that's a good thing.

mud

 

How would that work? Since the seat's attached to the frame and not the shocks, I can't see how you can lower the seat without changing the trail geometry. The only way tolower the seat one inch, is to lower the rear of the frame an inch which means the the frame will pivot around some center and change the angle of the steering head. The line from the steering head to the ground will move forward, while the contact patch of the front tire stays stationary which means the trailwill increase. Or am I envisioning this wrong?

 

Lowering the rear by 1 inch will increase the trail slightly but it will not get you back up to stock trail. You may gain about 1 inch of trail but that will be about it. I would not be able to give a definite answer without having your bike here to measure everything myself.

 

You're right splat.

The pivot would be at the front of the rear fork.

mud

 

Here is how to find your answer.

#1) go to this page: http://motorcyclemetal.com/Download.html

This is what is needed as far as almost your information goes than download a DOS type program on the bottom of the page. SAFE! No tracking BS on my site.

#2) Go to this page and read all but the two last pictures: http://motorcyclemetal.com/catalog2.html

This tells you how to get what measurements & how trail, offset, longer tubes/bigger diameter wheel works along with rake.

mudpuddle;Cutting the distance between eye to eye with rider sag included does effect the rake and trail(increses).

dex0807; Statement "Raked trees lower the trail" It is true if you reverse rake the raked tripple trees only.

cjhumphrey; "When I changed my front end I mistakenly put a -2" on instead of stock". what you did was change the trail more towards a zerro trail. With incresing the length tubes to +2" over stock you incresed the trail to more than stock.

In the future I will add to my site both tire sizes, diameter, and weight of tire. I also have the stock length of forktubes for all models of HD.

 

Great information there Howard