carbon clamping paranoia

blablablacksheep

Question : when you washing your bike or doing work on it, is there anything actually wrong with clamping the bike to stand via seat post?

I know people say carbon and clamping omg horror, but seriously though I'm sure I've seen pro teams clamp their bikes via seat post.
If not how else you use a work stand Lol

nicklouse

a seat post is designed to be clamped.

muzzan

Hi,

I believe that you will be fine for light clamping (stands to reason as the seatpost is clamped by the seattube). However, in the spirit of better safe than sorry I bought a £10 alu seatpost to use for this purpose.

bernithebiker

nicklouse wrote:

a seat post is designed to be clamped.

Good answer. Short and to the point!

To Muzzan; here's what you do; cut off a little 3cm piece of the bottom of your carbon seatpost (you probably don't need it).

Place it in a steel vice and try to crush it. You will have quite a hard time.

From that moment on, you will no longer have to faff around swapping your post for an alloy one when you want to work on your bike.

danlikesbikes

bernithebiker wrote:

nicklouse wrote:

a seat post is designed to be clamped.

Good answer. Short and to the point!

To Muzzan; here's what you do; cut off a little 3cm piece of the bottom of your carbon seatpost (you probably don't need it).

Place it in a steel vice and try to crush it. You will have quite a hard time.

From that moment on, you will no longer have to faff around swapping your post for an alloy one when you want to work on your bike.

Sounds like 2 good bits of advice.

Whilst I was a bit worried myself about clamping mine I see it done all the time in my LBS to far more expensive & heavier (MTB's) without having any issues.

goonz

So is is more advisable to clamp the seatpost than the top tube? I am guessing I will be shouted at for suggesting this, but I last did it on the top tube which seemed fine to me?

foggymike

The top tube is never designed to take clamping loads. You'd have to be a little crazy or just one of life's gamblers to go down that route!

The seatpost one is interesting. Personally I wouldn't assume the same thickness and strength of carbon above the minimum insert line as it can be thinner higher up to save weight and add comfort.

I swap in a metal post when I want to clamp it, which I find isn't very often anyway. In fact thinking about it I might sell my workstand as I hardly ever use the thing!

Monty Dog

If I'm just doing general maintenance on the bike, I lightly clamp the toptube because the frame is better balanced in the stand - done this literally hundreds of times and yet to damage mine or anyone elses. Where I need to use stronger leverage e.g. bottom bracket, I put the bike on the floor because it's far more stable.
There's Youtube videos of a carbon Cannondale Taurine vs Hammer or Niner Fork being abused and you'll realise that carbon is far tougher than some folks make out

greasedscotsman

foggymike wrote:

The seatpost one is interesting. Personally I wouldn't assume the same thickness and strength of carbon above the minimum insert line as it can be thinner higher up to save weight and add comfort.

But that is a minimum insert, it's safe to drop the seatpost lower if you need to. The post needs to be designed to take the load of the clamp if is above the min insert line (if that makes sense).

navrig

Monty Dog wrote:

If I'm just doing general maintenance on the bike, I lightly clamp the toptube because the frame is better balanced in the stand - done this literally hundreds of times and yet to damage mine or anyone elses. Where I need to use stronger leverage e.g. bottom bracket, I put the bike on the floor because it's far more stable.
There's Youtube videos of a carbon Cannondale Taurine vs Hammer or Niner Fork being abused and you'll realise that carbon is far tougher than some folks make out

+1

I balance the top tube on the clamp then lightly close the clamp. I then slowly tighten the clamp by screwing it down rather than using the quick release clamp. That way I can feel for how tight it is and avoid a shock load.

I adopt the same process when putting the bike on the car roof rack.

foggymike

@ Greasedscotsman, fair point, not got my head screwed on right there! :roll: Some posts do have a max insert line though which would be a different matter. Presumably they are the ones that get thinner higher up.

andi1363

nicklouse wrote:

a seat post is designed to be clamped.

No its not. Its designed to be clamped below the minimum insertion line not above.

nicklouse

andi1363 wrote:

nicklouse wrote:

a seat post is designed to be clamped.

No its not. Its designed to be clamped below the minimum insertion line not above.

Errr think what you have typed.

bernithebiker

andi1363 wrote:

nicklouse wrote:

a seat post is designed to be clamped.

No its not. Its designed to be clamped below the minimum insertion line not above.

And if you're a shortarse and have the seatpost fully pushed into the frame????

No problems clamping to seatpost.

A bit risky clamping to toptube even lightly - fine for normal use, but what if you fell and hit/grabbed the front/back wheel? Or the stand fell over?

VTech

Just to add. The seat post is usually safe as it is made with a central divide which gives added strength.
Carbon is flexible, it is also a fibre which can and does crack and shard so thought is required as to clamping power. As long as your careful it should be fine but balance plays a part when clamping with the seat post on bikes due to the frontal weight displacement being greater than the rear (post seat-post)
You don't want the bike tipping forward balance causing stress so having a firm grip is better than a loose grip.

pride4ever

Lol Carbon.

navrig

bernithebiker wrote:

andi1363 wrote:

nicklouse wrote:

a seat post is designed to be clamped.

No its not. Its designed to be clamped below the minimum insertion line not above.

A bit risky clamping to toptube even lightly - fine for normal use, but what if you fell and hit/grabbed the front/back wheel? Or the stand fell over?

Or worse, you might spill your coffee on it and the CF would melt!

sporttourer

Is there not also a risk of "squashing" a thin alloy seat post or top tube if you overtighten the clamp?

VTech

Finger right and half a turn.
It's served me well for years.

Gypsies

Or get a workstand like i've got where the frame rests on the b/b shell and you take the front wheel out,or you spin it round and take the rear out,depending on what your working on.

Monty Dog

For all those worried about 'crimping' their carbon frames in a workstand...
http://www.youtube.com/watch?v=SDVpRSNtcPQ

ellotreacle

I don't want to high jack the thread but I have a similar situation, I usually carry my aluminium bike on the roof of my car using my thule 591 (clamps the frame). I have just ordered a new carbon bike and wonder if this will be ok or do I need to look at a new way to carry my bike???

Thanks

desweller

VTech wrote:

Finger right and half a turn.
It's served me well for years.

Yup.

Don't use the over-centre action of the clamp to grip the tube (whether it's the seat post or top tube or whatever) as you can't predict how much load the clamp will apply. Wind the clamp up to the tube and then add 1/2 a turn.

FergySteve

ellotreacle wrote:

I don't want to high jack the thread but I have a similar situation, I usually carry my aluminium bike on the roof of my car using my thule 591 (clamps the frame). I have just ordered a new carbon bike and wonder if this will be ok or do I need to look at a new way to carry my bike???

Thanks

The official guidance from Thule is to use the fork-mounting rack (can't recall the number) as opposed to the one with the frame clamp for carbon frames, but I have seen plenty of 591s used to carry carbon bikes.

ellotreacle

FergySteve wrote:

ellotreacle wrote:

I don't want to high jack the thread but I have a similar situation, I usually carry my aluminium bike on the roof of my car using my thule 591 (clamps the frame). I have just ordered a new carbon bike and wonder if this will be ok or do I need to look at a new way to carry my bike???

Thanks

The official guidance from Thule is to use the fork-mounting rack (can't recall the number) as opposed to the one with the frame clamp for carbon frames, but I have seen plenty of 591s used to carry carbon bikes.

Thank you, I suppose just don't over tighten it then.

rich164h

I can't help but think that this really isn't something to worry about unless you are really over-tightening the workstand clamp. Think about it, when the seat post is clamped normally in the bike it has to be done up tight enough so that 70, 80, 90 or 100kg of rider is able to bounce up and down on it on a bumpy road and the post must not move. To achieve that there must surely be a significantly higher amount of clamping force than on a workstand where the clamping has to support 8-10kg of weight only, and in a environment where the bike isn't being shocked up and down. I've not got a workstand but I'd have thought that the clamps were also coated in rubber to protect the bike so that will also provide a grippier surface and hence the clamping force needed is even lower.

It sounds to me that if someone is clamping a bike in a workstand to the point where it might damage the seatpost they are over-tightening it way beyond the tightness that is needed.

Scrumple

I'll hijack this...

What about my carbon Wilier with a nicely painted ISP??

Never have a clue where to clamp it - there is no where!

FergySteve

ellotreacle wrote:

FergySteve wrote:

ellotreacle wrote:

I don't want to high jack the thread but I have a similar situation, I usually carry my aluminium bike on the roof of my car using my thule 591 (clamps the frame). I have just ordered a new carbon bike and wonder if this will be ok or do I need to look at a new way to carry my bike???

Thanks

The official guidance from Thule is to use the fork-mounting rack (can't recall the number) as opposed to the one with the frame clamp for carbon frames, but I have seen plenty of 591s used to carry carbon bikes.

Thank you, I suppose just don't over tighten it then.

Yeah, I would say so. Like I say, I have seen plenty of people using these racks in the car parks of various events and they have £*,000 bikes on them and noone seems to have an issue. Probably just Thule playing it safe so they don't get claims for wrecking people's frames if someone wrenches it too tight!