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idea to build springer to reduce trail a little

Posted: Mon Sep 11, 2017 10:30 am
by Dozer
I wanted to ask a question of some with some experience with building front ends so I thought this is the place to do it.
I was thinking of maybe changing the front end on my rigid and maybe building a springer from the plans here or something similar. I've had this bike 5 yrs, runs great rides good just a little stiff on steering because best I can measure the trail is about 8 1/4" and I'm always changing things on it so thought I might as well work on the front end too, I can always go back if I don't like it.

here's my bike, not sure of the exact dimensions best I can measure I think it's about 6" up 5" out, 45 deg rake with stock Deuce trees.
CD bike.jpg
CD bike.jpg (124.5 KiB) Viewed 5089 times
I thought about just changing to raked trees with a little longer tubes but haven't seen any trees I like as much as these, so started kicking around the idea of building a new front end completely and while measure things up I thought, I like these trees why not use them if I can.
I mocked up this quick model from different models on grabcad to get an idea of what I'm thinking. Not a complete design just a quick concept so I'm sure it's not 100% correct.
I've seen a few pictures of springers like this and I like them as much as a traditional springer and would be different than most, I could make new tube from DOM to mount in the tree and create end caps and rockers to move the wheel out about 3" - 4" and reduce the trail using the same wheel.
Would that make handling worse ? is it a stupid idea or waste of time ?
my_Fork-Assembly.jpg
my_Fork-Assembly.jpg (35.47 KiB) Viewed 5089 times
Probably a fork brace of some type or at least a front fender mount would help now that I see it, I think it's 42" along the fork tube now from the top of the bottom tree to the axle center but not 110 % sure on that I need to measure again.

Just kicking the idea around what do you think...

Re: idea to build springer to reduce trail a little

Posted: Mon Sep 11, 2017 11:49 am
by Dusty-Dave
Hard to judge a rake angle from a picture. Around 40 deg? Does it have chopper flop or just heavy steering? Flop usually starts around 40 deg If it's just heavy that should be a good solution. If it's flop ie with the bike vertical and not moving when you turn it so far the wheel pulls itself to the side. Flop is harder to deal with, traditionally either reduce the rake or Sugar Bear style rockers that reduce the leverage of the wheel on the frontend. Or a little on the fringe chain fork stops with springs or tailgate struts.
Dusty

Re: idea to build springer to reduce trail a little

Posted: Mon Sep 11, 2017 11:36 pm
by hansgoudzwaard
The inverted forks look great, but it may be easier to build new trees with more offset and use the forktubes you have now.

If I have this allwrong, please ignore.

http://www.choppercompendium.com/ccforu ... f=39&t=864

^^^^^^^^^Jeff's Build^^^^^^^

Re: idea to build springer to reduce trail a little

Posted: Tue Sep 12, 2017 8:44 am
by Dozer
I have put an angle gauge on the frame and tubes and with the bottom frame rails level the neck and tube show around 43 - 45 deg not sure how accurate that measurement is with a cheap gravity angle gauge but it's some idea.
It is really just heavy steering at speed. I don't have a problem with flop probably mostly because the trees rotate probably only like 25 - 30 deg each side due to the fork stops hitting the frame, they have been ground a little to allow front end to turn and Ive thought about grinding them more if I take the front end off with a angle grinder just to give a little better turning radius.
I'm thinking if this is not just a total useless Idea I can experiment with the rockers length and offset, to get the trail where I want it, thinking 3 -4 " less would be better, I've got a CNC mill so making a few different sets to experiment won't be a big deal to get it right then probably machine a final set with proper bushings and grease fittings to be plated if I like the end result.

Re: idea to build springer to reduce trail a little

Posted: Tue Sep 12, 2017 8:04 pm
by hansgoudzwaard
Dozer wrote: Tue Sep 12, 2017 8:44 am
It is really just heavy steering at speed.
At what speed?

Re: idea to build springer to reduce trail a little

Posted: Tue Sep 12, 2017 9:38 pm
by Dozer
[/quote]

At what speed?
[/quote]

Above 40 it's real stiff, not dangerous just seems tight.

Re: idea to build springer to reduce trail a little

Posted: Tue Sep 12, 2017 10:27 pm
by curt
those inverted springers look pretty but ive heard they don't handle too well however I have never ridden one myself . but with a cnc mill you should be able to experiment with different trees just as easily as rockers . if your looking for numbers and such talk to krymis or customize it both real smart guys . krymis has lots of posts on springers and all the geometry also gary's original build on the cd has tons of info

Re: idea to build springer to reduce trail a little

Posted: Tue Sep 12, 2017 11:29 pm
by hansgoudzwaard
Jack your bike up so the front wheel does not touch. Is it hard to turn either way when elevated?

Re: idea to build springer to reduce trail a little

Posted: Wed Sep 13, 2017 7:02 am
by Dozer
No it's nice and smooth and turns freely, I adjusted the nick bearings when I got the bike they were loose and sloppy

Re: idea to build springer to reduce trail a little

Posted: Wed Sep 13, 2017 10:06 pm
by Jim Sawyer
My inverted springer rides nice,I can ride with no hands and it tracks straight. I have about 4.5" of trail. I followed a set of plans and used springs called out on the plans. They were not stiff enough. What would happen is that if you steered the forks most of the way to either side, like parking lot maneuvers, the wheel would rock sideways a little due to the rockers moving independently of each other. I overcame this by using very stiff die springs instead. the only negative is that the rockers do not move very much unless you hit a very bad bump, so it is a very stiff ride. Another way to overcome the problem would be to have a bar, or someway to tie the spring rods together. (it could be used as a place to mount a fender if you want one)
While I am not unhappy with My inverted springer, If I was to build another, I would seriously consider using Gary's plans.

Re: idea to build springer to reduce trail a little

Posted: Thu Sep 14, 2017 4:31 am
by gearhead1951
another way would be to make your axle and rockers perform as a solid unit ! Make flats on opposite sides of the axle and holes to match in the rockers (like the "double D " join in automobile steering shafts) ! With the rocker surface a little "proud" of the ends of the flats on the shaft the axle and rockers will be immovable to each other once the axle nuts are torqued !

Re: idea to build springer to reduce trail a little

Posted: Thu Sep 14, 2017 7:34 am
by Dozer
Thanks Jim Sawyer, I was thinking about that yesterday wondering how they would act independently, I'd just have t make it rigid enough but Imagine a stiff ride is probably normal for this kind of fork..

I'd like to see yours, got any pics ?

Re: idea to build springer to reduce trail a little

Posted: Sat Sep 16, 2017 9:13 am
by Jim Sawyer
one pic while building using smaller springs, the rest are with the heavier springs

Re: idea to build springer to reduce trail a little

Posted: Sat Sep 16, 2017 4:40 pm
by Dozer
Curt, thanks I didn't notice your post till jun now for some reason. I'll search for krymis posts for some info. I've thought about making some raked trees too just a bit more money and time, but I might try it too.

Thanks for the pics Jim, very cool front end

Re: idea to build springer to reduce trail a little

Posted: Sun Sep 17, 2017 5:50 pm
by curt
your very welcome I look forward to seeing your build I love springers