Straight frame

what are some simple method 1 could use to check a frame for true? assuming a guy(like me)doesn’t have a frame jig or fancy equip.?
Is there a string method or something?
It seems u would need a straight line through the neck, and 1 through the swing arm pivot. how would u create these lines, and check to see if they are perpendicular ?
:S

Mark, Many years ago I worked at a shop which had a "frame straightening "box". & it employed just as you surmise,.. A pair of collets surrounded the swingarm pivots. and were secured to uprites of "box". Steering stem removed and a rod w/tapered cones passed thru neck & secured. Said rod was adjusted to relate to "box's" table allowing for measuring center, & rake. rear axle in sittu was used for determining s/a level. Staightening/mods were performed via a Porta-pack, & "blue-tipped wrench". for simple check, neck rod & cones & some means of leveling frames' S/A stancion should suffice. BTW,Typical undamaged frames were usually 2-4 degrees out of true. luck G PS, a worthless asside, while axles,swingarm pivot & neck are generally supposed to be parallel/perpendicular, wheels arent' always in line. Some bikes w/engines carrying their weight/mass off-center are designed w/off-set wheels. I'm not sure how you'd research this, but perhaps a shop w/"laser straightening" facilities could help..G

gane wrote:

Mark, Many years ago I worked at a shop which had a "frame straightening "box". & it employed just as you surmise,.. A pair of collets surrounded the swingarm pivots. and were secured to uprites of "box". Steering stem removed and a rod w/tapered cones passed thru neck & secured. Said rod was adjusted to relate to "box's" table allowing for measuring center, & rake. rear axle in sittu was used for determining s/a level. Staightening/mods were performed via a Porta-pack, & "blue-tipped wrench". for simple check, neck rod & cones & some means of leveling frames' S/A stancion should suffice. BTW,Typical undamaged frames were usually 2-4 degrees out of true. luck G

gane, i'm getting some of this, but i'm not getting all of your termenalogy.
1.A pair of collets surrounded the swingarm pivots.collets?
2.rear axle in sittu was used for determining s/a level. sittu?
3."blue-tipped wrench". Sleg hammer?
4.S/A stancion should suffice. Stancion?

I get the Steering stem removed and a rod w/tapered cones passed thru neck & secured. that seems like something that could be made fairly cheaply. just 2 cones on a threaded rod. (must be ridged and straight)
i suppose u could do the same in the swing pivot sleeve. now how do i check for alignment?

Mark, collet, a circular surround, in this case encapuslating s/a pivot bolt, & mating to frame.In sittu,in place. Blue tipped wrench, a torch, oxy/acetelene welder, stancion, the crossmember of frame, in this case the one which holds swingarm bolt & bearings.sorry for being obscure..G alignment, easy, string, 2x4's, neon light bulbs, pretty much anything straight & long enough to straddle rear wheel & go to front wheel.unfortunatly, all this tells you is if wheels are true to each other & in line. not if neck is true...G

Thanks for the response.
I have already verified the front to rear wheel for true. I used 2 straight edges from the rear rim to the front rim. i was able to get then parallel, but not in line. The rear wheel is no longer in the center at the back. this leads me to believe that something is bent. most likely the steering head?

Parallel is fine.

Many new bikes do not have tire center-lines exactly the same.



Good Fortune!

Patton wrote:

Parallel is fine.

Many new bikes do not have tire center-lines exactly the same.

Good Fortune!

Mine is like the center now. in order to get it in line and center it in the frame to make room for a 200 tire, i need to straighten things out.

start with a level across the bottem 2 backbone tubes where coils mount and another across top of steering head with trees and front end removed is the area id be looking at.

PLUMMEN wrote:

start with a level across the bottem 2 backbone tubes where coils mount and another across top of steering head with trees and front end removed is the area id be looking at.

How do u referance the 3 levels to each other? Not sure what this is going to tell me?:side:

I have a Stanley laser that I bought at Home Depot that shoots a horizontal line, a verticle line, or both at the same time. It will shoot a perfect 90 where the lines cross, this may be the way to get the head and rear pivot square to each other. Without expensive equipment this would be my choice for the do it at home method.

mark1122 wrote:

Patton wrote:

Parallel is fine.

Many new bikes do not have tire center-lines exactly the same.

Good Fortune!

Mine is like the center now. in order to get it in line and center it in the frame to make room for a 200 tire, i need to straighten things out.

Assuming that you don't find a serious frame problem, and since the wheels are parallel, could you align them by using or rearranging spacers on the rear axle to shift the rear wheel left or right as needed? Ed

mark,here is what you need .




leon