yes tat2u, you did and it was greatly appreciated. I have also been intouch with a fairly well known custom bike builder that does these conversions for a living and he insists that I use fat bob trees instead of FXDWG. I want to use 17 rear and 21 front with fxdb hubs and sliders and I thought exactly what you and the poster before you said, that i should use fxdwg trees because fxdwg comes stock a with 21 up front but the custom builder says I shouldn't. He is addiment that I go with fat bob trees and lower the bike 2".
I kept reaching out because I thought maybe the spacer sizes might change if used fxdf trees with fxdb oem hubs and sliders. I don't know anything about these conversions other than what I read and I have been told. I have noticed the spacer sizes change per the particulars of the application. I was hoping to get lucky and find someone who used the fxdb hub and sliders with fxdb trees.

 

By caliper spacer I actually meant both hub and caliper. I should have specified. I read where a few people said that you should split the difference, but like much to do with harly's ask two people and get 3 answers.

 

I don't know why the builder insisted on FXDF tree's ?

I used FXDWG and lowered 1 1/2" handles Great!!

 

I don't know either. I told him that I wanted to 17 rear a 21 Front but I wanted the front rim to be 2.5 " to possibly 3.5". I even brought up the fact that that fxdwg comes stock with 21". He does do a bit of performance type bobbers, so maybe he just prefers bikes with less rake. I'm not sure but I already bought the fxdf trees so it's either resell them and get fxdwg which i located for 150$ or just stick with fxdf.
great looking bike by the way!

 

 

Tree choice has nothing to do with wheel diameter. The only physical difference between them is the rake.

Adjust ride height for different tire diameters by altering fork tube length or insertion into the trees.

 

With more rake the front will sit lower, basic geometry

 

Yes, but if more rake, the same ride height and tire are desired, longer forks (or less insertion) get you there.

The relationships we're discussing here are fairly complex. Neck rake, tree rake, offset, fork length, tire diameter all come into play if you're trying to get to a specific handling goal. I understand the geometry, up to and including trail, but not all the handling implications. For instance, two bikes with equal trail but different rake...how do they handle differently, if at all? Of course, that's well beyond the scope of this topic.

 

Tat2u, when I said "a custom builder advised me not to use fxdwg trees", I wasn't reffering to you. I befriended one of the custom builders in the street bob scene who has been very helpfull but for some reason he is addiment that I go with fat bob trees and not wide glide. Sorry about the confusion. Got two conversations going on at once.
You have been straight forward with your info and I am totally clear on the route you took.