Seatpost rack?

[Todd75]

 I must be missing the concept of how this rack mounts to the post. On my standard post the clamp, when fully tightened has about 1\4 inch of space left over all the way around. It's like there is supposed to be a sleeve or collar that's supposed to go on first. Do you know what I'm doing wrong?

[Bikemad]

Seat posts vary tremendously in diameter so the rack has to be big enough for the largest seat posts too.
If your seat post is too small for the rack mounting you will have to use something to pack it out to the required size, like a piece of suitable rubber hose or thick rubber sheet, short sections of PVC pipe with slots cut in, or simply bind the seat post with masking tape or something similar until the diameter is large enough for the rack mounting to clamp onto securely.

Alan
 

[Todd75]

I had no idea seatposts came in various sizes. Thanks Alan.

[Bikemad]

If you take a look at this webpage you can see there is half an inch difference between the smallest and the largest ones shown.

Alan
 

[Mgizen]

I was wondering about a seat post rack for the GM 48v 10ah battery are these racks able to support the weight of this battery safely?
thanks