Seatpost slips downwards

[sidmarx]

Other threads here deal with stuck seatposts, this is the opposite case.
My weight (200 lbs. +) makes my legs get longer as i ride, so i came up with some maybe helpful suggestions...

Tightening the frame bolt squeezes the 2 ears on the frame together so that they're no longer parallel. That limits how far the bolt will tighten. I tried a thinner q.r. bolt using those ball washer thingies from v-brake pads contacting the frame surfaces. This helps prevent the q.r. bolt from bending under load while toeing in for better contact.

Also tried one or more alu. seatpost clamps directly on the seatpost. You match them to the seatpost diameter and file off the thin inside flange that normally keeps the clamp on top of the frame. This added resistance should keep the post from sinking. The bolts on these clamps also tend to bend under stress unless ball washers are put against the clamp surfaces.

Anyway, i hope the explanation makes sense.

[Jordan300]

Is the seat post the right size? There are like 37 different seat post sizes.

[sidmarx]

Absolutely. It came stock with the new bike, and when the clamp screw is released i have to pull and twist to get it out. (zigzag grease marks on the post.) I greased the post against better judgment as recommended by Sheldon Brown but find it hard to believe he cd. be wrong about anything.

Anyway the rig seems to be holding up. The above comments were offered as a poss. solution for other sufferers of folding bikes. The seatpost does look like a wind instrument though.....