Rigid_EVO Chopper "stock dimensions"

jazzman · #1 13th June 2012

I keep seeing chopper frames advertised as "stock dimensions" but invariably when the bike is built the forks are "2 inch under", or they are right up higher in the yokes to get the lower frame rails level.
What gives?

tobiism · #2 13th June 2012

It has to do with the location of the rear axle after its been hardtailed. The rear of the bike gets lower so unless you extend the front downtubes you have to slide the forks up a bit to level the frame.

wagoneer12 · #3 13th June 2012

I believe the 'stock dimensions' are usually something like 0" backbone stretch, 0" front leg stretch, and 30 degree rake.

Well....if the frame has all of that......and it is usually lowered....ALOT. Like 3-4 inches of ground clearance. In order to have level frame rails with the ground...the front end needs to be shortened....i.e....2 under....or run the tubes up in the trees a couple of inches.

jazzman · #4 13th June 2012

Yrah, that's what Im thinking wagoneer, but why lower the frame rails/
I believe the "stock" thing is based on knuckle dimensions.
If I buy a paughco or flyrite freame, I want to be able to bolt ll my sporty stuff straight on.
Maybe it doesn't look right with the correct ground clearance? But 4 inches isn't much!

jharback · #5 13th June 2012

I could be wrong but, I think he may be referring to the front ends. Sportster front ends come stock, 2 inches under (meaning 2" shorter than stock Big Twins).

jazzman · #6 14th June 2012

When I get on the computer I'll post some pics of what I mean.

wagoneer12 · #7 14th June 2012

I believe 'stock front end length' in all the catalogs....is 22 inches from bottom of the neck to axle hole.

So.....from there.....call things +2, 0, -2 etc......based on 22 inches as 0 which I think is big twin.

Now....I have 2004 XL front end that has progressive springs and is 23 inches from stem to axle. (implies stock is 23)

I have a 1967 front end with "4 over" tubes and it is 25.5 inches from stem to axle. (implies stock is 21.5)

Lastly I have a DNA Springer that is "+2" and is actually 24 inches, which would relate to a big twin stock of 22".

Typically...a chopper frame...such as a Flyrite that is lowered......will work with -4, -2, 0, or +2...but its all about getting the frame rails level (usually) and since the bike is lowered, or the as Tobiism describes it "rear axle is lowered". I personally, like the front of the bike a little higher.

I believe the flyrite frame...which is raked to 33 degrees and lowered.....which offset each other in regard to effects on front end length.....would look fine with a 'stock front end'...I might even want a +2 on it. Ultimately...ask them what front end to run.....they are cool guys and I have emailed them in the past about their frames.

I got this email from Jason at Flyrite about the 6 up 4 out, 40 degree frame..........
=========================================
Hi Vic,

Thanks for the email. For this frame, front end of 12" over to 14" is what we recommend. That would be for a 21" front and 16" rear. The frame does not have a cross over tube.

I'm having foot surgery and it's going to suck, I have to be off my foot for 6 weeks.

Jason

jazzman · #8 14th June 2012

Check this one (which I really dig) The lower frame raills still rise slightly but see how short the forks are!

Mod Chopper Sportster Bobber - YouTube

Thanks, wagoneer. Maybe I'll just emai Jason.

jharback · #9 14th June 2012

When ordering a Springer Front End, for lets say an FXR, you would order a 0" extension if you wanted stock length with stock rake and trail. For a Sportster you would order a -2" to maintain the stock length along with the stock rake and trail.

This is where I get that the front ends on sporty's are -2".

wagoneer12 · #10 14th June 2012

Quote:

Originally Posted by jazzman

Check this one (which I really dig) The lower frame raills still rise slightly but see how short the forks are!

Mod Chopper Sportster Bobber - YouTube

Thanks, wagoneer. Maybe I'll just emai Jason.

Dude! That bike has like 2 inches of ground clearance....notice the pipes are high...no way to run them lower. That bike probably has the springs chopped inside the tubes. not much travel.