Seat post clamp size?

[jmsgld]

Looking to use quick release seat post clamps in adjustable speaker stands.

The clamps come in 28.6, 31.8 or 34.9 mm, please can someone tell me if this refers to the internal diameter of the clamp at it's most closed position, or the diameter of the outer tube it is intended to be used with.

Alternatively what dimensions of ally tube are normally used.

Thanks, James

[snotrag]

The names relate to the nominal outsider diameter of the seat tubes they fit - note that the common sizes listed above all translate to an imperial sized tube.

There's a fair bit of variance due to paint/powdeecoat finishes and most seat clamps will be flexible enough to cope with this.

[Some Gump]

Those.are the OD's of the seat post itself.

So you have e.g 27.xmm seat.post, 2 walls of bike frame material, then the clamp round that.

Edit scratch that, 27.2mm and 31.6mm are 2 of the standard post sizes. Your ones must presumably be the ID's that match those sizes.

Edited by Some Gump on Tuesday 25th February 22:07

[take-good-care-of-the-forest-dewey]

Some Gump said:

Those.are the OD's of the seat post itself.

So you have e.g 27.xmm seat.post, 2 walls of bike frame material, then the clamp round that.

Seat tube... Not post.

[jmsgld]

That was quick! Thanks,

So sizes relate to the nominal OD of the outer tube ie the one that the clamp is in direct contact with and exerts pressure upon.

So I am to buy 2 tubes, the larger of which the same nominal size as the clamp.

Cheap ebay Chinese anodised ally jobs ok? They will of course be self isolating for 14 days...

Many thanks, James

[take-good-care-of-the-forest-dewey]

jmsgld said:

That was quick! Thanks,

So sizes relate to the nominal OD of the outer tube ie the one that the clamp is in direct contact with and exerts pressure upon.

So I am to buy 2 tubes, the larger of which the same nominal size as the clamp.

Cheap ebay Chinese anodised ally jobs ok? They will of course be self isolating for 14 days...

Many thanks, James

Yup.

Remember to slot the end of the outer tube. The bottom of the slot to be drilled and of larger diameter than the slot width
- stops crack propagation.

[take-good-care-of-the-forest-dewey]

take-good-care-of-the-forest-dewey said:

Yup.

Remember to slot the end of the outer tube. The bottom of the slot to be drilled and of larger diameter than the slot width
- stops crack propagation.

Oh and be careful with bare ally on bare ally - it can corrode and the cold weld when you attempt to twist it free... Ask me how I know this

[jmsgld]

Great, thanks for the help.

[jmsgld]

take-good-care-of-the-forest-dewey said:

Oh and be careful with bare ally on bare ally - it can corrode and the cold weld when you attempt to twist it free... Ask me how I know this

Ah, will be permanent outdoor installation, silicone, lithium grease?

What did you ruin, a bike?

[gazza285]

jmsgld said:

Ah, will be permanent outdoor installation...

Why do you need adjustable stands if it is a permanent installation?

[take-good-care-of-the-forest-dewey]

jmsgld said:

Ah, will be permanent outdoor installation, silicone, lithium grease?

What did you ruin, a bike?

It depends on what you mean by outdoor and permanent... Silicone grease washes out over time. So you'd need to re-grease regularly.

Zinc based or maritime grade anti-seize paste would be better if they're left out in all weathers.

Cold welded the post into the tube twisting it back forth to get the non greased post out. Handy my father was a tool maker in the 70s and 80s. He took the frame into work one Saturday morning and it came back good as new. Needed a new post mind.

[jmsgld]

The house is towards the bottom of a large valley, the garden is split into 2 terraces, the terrace wall continues up to form a raised bed that surrounds a patio area. The speakers are currently mounted on that wall facing the patio and house, the main garden is on the lower terrace.

The adjustable stands will be mounted in the same place, but allow the speakers to telescope up a foot, and twist to peek over the wall and face into the main garden area. That's the idea anyway. ..