Aluminium frame and workshop stand

[cavasta]

I've got a Trek 2.3 road bike, which has an aluminium frame and carbon seat post. To minimise any accidental damage that may occur when tightening/attaching the bike to the clamp on a workshop stand, where's the best place to apply the clamp - seat post or frame? I seem to remember reading somewhere that alu and carbon are both sensitive to this sort of pressure.

[Malaconotus]

To be completely safe, I'd buy a cheap alloy seatpost to swap in. Should be able to get one for about ten to fifteen quid online. Push and Kalloy are cheap on Ebay usually.

[CREPELLO]

I wouldn't feel happy clamping a carbon seatpost, but I can't see that clamping the seat tube would harm the post, but that's only my opinion. I don't have carbon.
I never do any really high torque wrenching (BB's etc) on the frame myself - it doesn't feel totally safe somehow.

[Steve Kish]

Exotic do a very neat double clamp that tightens against the frame and the seat pillar above it. You only need to tighten this to a nip. Plenty on eBay, most sizes. I had one and it was great.

Back to topic - I clamp alloy and carbon frames in mine with no problems. A bit of rubber tube around the clamp helps.

[Valbrona]

I would only clamp a high quality aluminium frame with thin tubes at the top of the seat tube. The seat tube will have the thickest wall thickness of the three main tubes. I would not clamp a high quality aluminium frame on the top tube; top tubes have the thinnest walls. I remember I once came across an aluminium Klein the top tube of which you could dink in with just thumb pressure, before it would dink out again. If your bike has a carbon seatpost then your frame is probably a good one and falls into this 'high quality' category.

If we are talking cheaper aluminium frames with thicker walls then clamping on the top tube would be okay. I am mostly thinking here of non-butted/plain gauge tubes.

Carbon fibre is what you should really never put in a clamp. Despite its high strength to weight ratio, it is really not very good under compression. See Tacx Spider for a good under BB shell/front fork workshop stand. That said, carbon seatposts do have thicker walls than the main tubes on a bike frame.

[Ayesha]

Can I ask a stupid question?

What job on a bike requires the bike to be clamped in a stand?

[Mick F]

I bought a stand only recently, and I have no idea how the heck I managed for all those years without one!

Jobs?
Any job you can envisage is easier with a stand. Everything can be adjusted to the best working height/position for you. The bike can be turned/raised/rotated - even fitted upside down or vertically - and clamped in a wide variety of places.

It's surprising how little pressure is required on the clamp, and sometimes I just "hang" mine from the top tube at the seat post end.

[thirdcrank]

To be completely safe, I'd buy a cheap alloy seatpost to swap in. Should be able to get one for about ten to fifteen quid online. Push and Kalloy are cheap on Ebay usually.

Until I saw the subsequent posts, I should have assumed that this was the universal answer. Around ten years ago or so, Park Tool used to advertise an accessory which did much the same thing but was a bit like a very squashed letter J so once it was in the frame, there was a tube running parallel with the seat tube for the clamping, presumably to get a bit more height. I've never seen one and my memory is a bit vague about the detail. The problem must have been having one standard size to fit all seat tubes.

I checked the Park Tool site to see if it was still advertised and they now offer this:

http://www.parktool.com/product/interna ... lamp-isc-4

[cavasta]

Thanks for all the replies - much appreciated. While we're on the subject of removing seatposts, what is the recommended type of anti-seize grease to use with an alu frame/carbon post? Will copperslip or a general purpose grease do, or is there one with a special compound I have to use?

[Mick F]

Carbon seatposts should be inserted dry and clean I believe. Never had one ...... yet.

Coppaslip is excellent for metal seatposts, but I understand you should use Aluslip.

[Malaconotus]

Thanks for all the replies - much appreciated. While we're on the subject of removing seatposts, what is the recommended type of anti-seize grease to use with an alu frame/carbon post? Will copperslip or a general purpose grease do, or is there one with a special compound I have to use?

You shouldn't use grease with carbon as it will increase the clamping force required and, according to manufacturers quoted here, can damage the seatpost... http://www.bikeradar.com/forums/viewtop ... t=12534958.

We sell this stuff for carbon part fitting... http://www.edinburghbicycle.com/ebwPNLq ... =-1&f_bct=. I am not, however, a materials scientist and cannot comment on its necessity, but I do not believe it to be snake oil.

[Valbrona]

Thanks for all the replies - much appreciated. While we're on the subject of removing seatposts, what is the recommended type of anti-seize grease to use with an alu frame/carbon post? Will copperslip or a general purpose grease do, or is there one with a special compound I have to use?

Absolutely never use grease on a seatpost. Grease is for lubrication. If used on a seatpost there is the obvious tendency for slippage, and higher tightening torques are needed to prevent this from happening. Bad idea.

If we are talking metal seatpost in metal frame use an anti-seize compound, but not the copper-grease type ones used for lubrication. Instead, use a thin/sprayable anti-seize compound, the likes of which Loctite produce.

For a carbon seatpost inside an aluminium seat tube I would use carbon assembly paste. Tacx do it.

[pete75]

If we are talking metal seatpost in metal frame use an anti-seize compound, but not the copper-grease type ones used for lubrication. Instead, use a thin/sprayable anti-seize compound, the likes of which Loctite produce.

Copper grease is an anti seize compound. It is not intended for lubrication.

If you're worried about squashing your frame tubes why not wrap grey plumbers pipe insulation round the cross bar. It will reduce the clamping force on the tube and spread the pressure.

[cavasta]

Thanks again for all the replies - all interesting, useful and appreciated.

[g00se]

Yes - use a carbon assembly paste. it's a viscous liquid with very very small 'beads' in it. Get it on your fingers and it feels gummy and gritty.

Squashed between two surfaces, the beads make it hard for them to slip - so you need less pressure to stop it moving - hence less torque on the seat post clamp.

I even use it when fitting aluminium bars to aluminium stems - less change of things sliding about when tightening it all up.