Modified springer trail

Information on forks/springers/shocks
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txpan49
Posts: 29
Joined: Fri Sep 12, 2014 10:12 am

Modified springer trail

#1

Post by txpan49 » Wed Aug 24, 2005 1:13 am

Guys,
I picked up a 49FL with an old springer front end that has been lengthened 8" over (30" overall). The 50 wishbone has been raked but I do not know how much. Its tough to steer at low speed but tracks straight at higher speeds. Using the tape measure process I calculate the trail to be 7". So, I have some questions,

1. Can I change the trail to shorten it by changing to longer rockers?

2. If I lower the forks by having a shop cut them down to 4" over will that affect the trail? I can't figure that one out logically.

Thanks,

Txpan



caschnd1
Posts: 589
Joined: Tue Apr 25, 2006 3:45 pm
Bikes: 1949 FL Chopper

Re: Modified springer trail

#2

Post by caschnd1 » Wed Aug 24, 2005 2:02 pm

Txpan,

There are a number of good rake & trail calculators available online. Here is one:
http://www.rbracing-rsr.com/rakeandtrail.html" onclick="window.open(this.href);return false;

I think for this calculator, you'll need to include the length of your rockers in the triple tree "offset" number.

You might find some more good information at:
http://flyingsnail.com/Sprung/sprungcontent.html" onclick="window.open(this.href);return false;

Here are the short answers to your questions:

1) Yes, you can achieve a shorter trail number by using longer rockers with a springer.

2) Yes, cutting down the length of the fork will shorten the trail.

Hope the links are helpful.

-Craig

caschnd1
Posts: 589
Joined: Tue Apr 25, 2006 3:45 pm
Bikes: 1949 FL Chopper

Re: Modified springer trail

#3

Post by caschnd1 » Thu Aug 25, 2005 7:54 pm

Let me add one thing about my answer to question #2...

If you were to cut down the fork it lowers the front of the frame and changes the effective rake angle of the neck in relationship to level ground (results in a smaller rake angle). This is why you get a smaller trail number by cutting down the forks. Now, if you also adjust your neck angle so it remains the same, cutting down the forks would have no effect.

Hope that doesn't just make it all more confusing...

txpan

Re: Modified springer trail

#4

Post by txpan » Fri Aug 26, 2005 11:33 am

Thanks that makes perfect sense. I want to retain the original HD Springer and I think this do the trick.

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