Will my conversion work? I have an old 2014 Giant Trance 1. It is a small frame. It is just a backup bike. It is still fun to ride and works well when a friend is or family member is visiting and bikeless.

I hate sending things to the land fill or not being able to keep them repaired and running. I already replaced the fork a couple of years ago. I already found some parts and converted to a through axle in the rear. To give myself better wheel and hub maintenance options.

All of this is to give options and flexibility for finding maintenance parts in the future as this thing gets older and older. The rear shock is end of life. I want to experiment with what I can use and get some more "wrenching" experience. I am not looking to go crazy with a super expensive new shock.

I found a good new 210 x 55 piggy back shock for the right price. The bike came with 200 x 50 no piggy back. I am thinking I could use M8 x 22.2 and M8 x 19.0 offset bushings, volume spacers, and an angled headset to use the shock even though it is too long.

Bushings to get a closer effective eye to eye length, volume spacers to compensate for longer travel and prevent bottom out, angled headset to compensate for change in bottom bracket position to keep effective head tube angle slacker.

I think I can get a pretty good franken bike setup and mostly maintain the original kinematics. I think it will give a much better shock with nice progression and ramp up and adjustment flexibility. Has anyone ever tried this approach? How did it go?

Any strategy for approximating fit without the new shock in hand

use the shock as-is, and add rear sag to compensate for the 10mm extra length.
there will be an advantage to having extra drop in back...improved ground contact, and a bit more cush when landing.

and the front angle change won't be enough t worry about anyway,,, you won't notice it at all, if it does change a half degree.

https://mtbdatabase.com/bikes/2014/g...trance-27-5-1/

I’d be careful, 210x55 is a big jump from 200x50 on a Giant Trance 1. Offset bushings won’t fully make up the difference. Mock it up and cycle the suspension first to check clearance before committing.

around 3/8" longer shock, 3/16" longer stroke... it's done quite frequently, to a variety of bikes.
easy way to "mock up" is to let all the air out, or remove the spring from a coiler... run the susp. thru it's travel range...
i bet it will be fine.

Thanks!! I am going try it. 2 offset bushings, 1 stroke reducer, 4 volume reducers, 35 % sag...

Thanks!! I am going to try it. 2 offset bushings, 1 stroke reducer token, 4 volume reducers, 35 % sag.... J curve air tune, longer bars

i think you completely missed the point... sigh.
good luck.