Springer fork

[Eddie Medley]

I got a lowrider Springer fork for my motorized bicycle but at high speed around 20 mph it gets a really bad wobble in it what would fix that so it is more driveable

 

[DuctTapedGoat]

I got a lowrider Springer fork for my motorized bicycle but at high speed around 20 mph it gets a really bad wobble in it what would fix that so it is more driveable

Aren't most Springer fork springs adjustable? My immediate thought would be to tighten the spring... is it wobbling at the spring or elsewhere?

 

[FurryOnTheInside]

If the new fork has more rake (forward offset) than the original fork, the trail will be reduced.
As trail is the product of head angle and rake (and wheel diameter), you must change one or both of these to get the trail you prefer.
More trail generally speaking gives better high speed stability and less nimble handling. Speed wobbles (although generally a rider induced phenomenon) occur at a higher speed as trail is increased.
Handlebar (grip) position and the way you rest your weight on the bars has an effect too. Road racing bicycles often have little trail but they have a very forward handlebar position.

 

[inspectorcritic]

I got a lowrider Springer fork for my motorized bicycle but at high speed around 20 mph it gets a really bad wobble in it what would fix that so it is more driveable

Check your bushing it may need to be replace or tighten mine was trash bought new rim. I chop my schwine put front end suspension the thing sits 7 inches higher same bike I had 50 years when I was a kid ditch was riding a friction roller bar called up the old company guy remember me and the pics of a Cumming .... (?) motor his competetion who infringed on his invention referred me to him they both had a laugh. I had problems then too it was an adult frame hard to mount then.

 

[DuctTapedGoat]

If the new fork has more rake (forward offset) than the original fork, the trail will be reduced.
As trail is the product of head angle and rake (and wheel diameter), you must change one or both of these to get the trail you prefer.
More trail generally speaking gives better high speed stability and less nimble handling. Speed wobbles (although generally a rider induced phenomenon) occur at a higher speed as trail is increased.
Handlebar (grip) position and the way you rest your weight on the bars has an effect too. Road racing bicycles often have little trail but they have a very forward handlebar position.
View attachment 76512
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So are you implying that a looser spring can lead to less of these wobbles?

A looser spring should cause a longer rake and less trail, right?

That a tighter or stronger spring could increase trail by decreasing rake increasing these wobbles?

 

[FurryOnTheInside]

So are you implying that a looser spring can lead to less of these wobbles?

A looser spring should cause a longer rake and less trail, right?

That a tighter or stronger spring could increase trail by decreasing rake increasing these wobbles?

Well, I suppose it depends on what the angle of the lower linkage plate is, as that affects it's length... I wasn't actually deliberately implying anything about the fork set up in my post though. I was just saying what may have changed in the geometry, where to measure the change, and that one if the easiest things to try is a longer stem.