This is a modification for a 1995 Sportrak Elxi to address the lack of legroom, I am 5’ 7” and I made two riser bars that would throw the seat back 3", and up 1” and this is how I did it.

I used three drills 20mm, 6.8mm and a 8.1mm, plus a M8 tap and four M8 x 25mm Allen socket bolts plus four M8 Nylock nuts and spring washers.

I cut two lengths of 25mm x 25mm steel box section 3mm thick, (minimum) to a length of 419mm.
I made two identical runners and the dimensions are the same for both of them. I first ran some insulation tape along the top face and marked a centre line along the length of the tube with a biro 12.5mm in.
Measuring from the right, I marked out and drilled a 6.8mm hole 17mm in from the end.
Then from that hole, drill another 6.8mm. hole, 290mm to the left of that hole, 290mm centres as we say.

Stage two, from the first hole, mark a spot 76mm to the left and drill another 6.8mm hole then again move 290mm to the left and drill another 6.8mm hole, so you should have two sets of 6.8mm holes at 290mm centres 3" apart.

Next tap two bottom holes in each bar with a M8 tap, they are the bottom first hole (17mm in) and the bottom second hole at 290mm centres, these will eventually have M8x25mm socket cap screws screwed in from above, that is why you must use thick wall section.
Now from above again from right to left, open the first top hole which is 17mm in from the end up to 20mm, the next hole along to the left 8.1mm the next 20mm and the last 8.1mm.
Do the second bar exactly the same.

The sizes on the top from LEFT to right should be 8.1mm- 20mm – 8.1mm - 20mm.
Turn both bars over and the two holes which have not been tapped M8 should be opened up to 20mm.
Next get four M8 Allen socket cap screws 25mm long and screw them in tightly through the box with an Allen key, so only the threads stick out. Looking at the box again they drop in the first hole from the right and the third hole from the right.

These eventually will bolt into the floor mount with M8 nylock nuts, which is fixed to the floor.

Take all the sharp edges off, clean the grease off, and spray matt black. Now if you undo and take out the four floor bolts and detach the seat from the floor mount, and then take the floor mount off the seat, you should be able to place these runners between the floor mount and seat which will give you a extra 1" in height and an extra 3" legroom which I found plenty.

The seat adjustment will still work, and I assembled the whole thing upside down on a workmate.

The only extra mod I had to do was an extra indent/hole to go over a dimple in the seat and this is how you do it. Looking at one of the bars again with the first hole 17mm in from the right and the M8 screws facing down, measure 242mm from the right hand end, and drill a hole or countersink between 13mm and 20mm.diameter about 3mm deep.
If you can look at your own seat assembly first to get your own measurements you can check the sizes you have. Bolt the 1"x1" runners to the seat using the original special nuts and bolts supplied, and then the seat to the floor mount with M8 “Nylock” nuts and washers. Then bolt the whole assembly to the floor with the original bolts.

The 20mm holes are to allow clearance for a socket to tighten the nuts. When bolting the runners to the floor mount I used spring washers and “Nylock” nuts so they do not come undone and I check them regularly.