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Old 05-12-14, 11:01 AM   #1
Rijnton
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How to secure a Brompton in a workstand ?

I have the Pedro's Folding Repair Stand
http://pedros.com/products/mobile-re...-repair-stand/
which I bought a long time ago for my Klein mountain bike, but now would like to use with my Brompton. I wonder however how I should clamp the Brompton in it.
On the Brompton website I found a video in which is adviced against securing the bike to the seatpost. However they are not very clear about the reason behind that. I always thought that it was better to use the seatpost, because that way the frame cannot be damaged. Moreover with my Brompton and the Pedro's stand I noticed that, when clamping to the frame tube, I have to do it near the main hinge because otherwise I cannot turn the cranks. And I have to be careful with the cables.
When clamping to the seatpost I don't have this problems and it is easier to lift the bike high enough.
My questions:
1) Does anyone know why Brompton advices against using the seatpost ?
2) Would it still be safe to clamp to the seatpost and if so, then near the saddle or near the seat tube ? And would it be better then to lower the seatpost as much as possible ?
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Old 05-12-14, 11:38 AM   #2
ThorUSA
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interesting ....
seatpost is all I ever use to clamp a bike

meaning a Brommy gets fixed with the mechanic laying on his back ?
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Old 05-12-14, 12:13 PM   #3
bargainguy
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Brompton is probably worried about seatpost wear causing folding/unfolding difficulties.

I don't have an issue with putting my M3L on a workstand via seatpost clamp.

Perhaps cover the seatpost with a rag before you clamp it - that way hopefully preventing you from gouging the seatpost with the workstand clamp.
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Old 05-12-14, 01:38 PM   #4
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Explained in this video: https://brompton.zendesk.com/entries...in-a-workstand

You risk too much force through the seat tube if clamped on the seat post, potentially damaging the frame and/or seat post. If you're set on clamping on the seat post, I'd lower the seat post as much as possible and clamp the workstand as close to the frame as possible. From what I understand, you can clamp the bike on the main tube either right-side up or upside down. Just depends on which is more convenient for what you're working on (I find upside down to be really convenient for wheel removal/reinstallation). Using a rag as a buffer between the bike and the stand is a good idea wherever you clamp the workstand.
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Old 05-12-14, 02:29 PM   #5
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Factory grips the main frame tube and their stand flips the bike over as they need to
To get to the other side while putting it together .

your own bike, the steel seat post tube is probably fine , after all your back side on the saddle is heavier than the bike itself.

Dont clamp it too tight, so as to not knock the tube out of round.

yea piece of old MTB inner tube in the repair stand clamp, would be a pad. but not slippery . like a Shop rag..

Last edited by fietsbob; 05-12-14 at 02:36 PM.
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Old 05-12-14, 02:42 PM   #6
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so let me get this straight .... if you clamp a 40 lbs or so Brompton with the seatpost, there is danger to damage the frame, but its quite alright to have a 200 lbs guy ride it down the street ....

something has to give .... or better not ...
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Old 05-12-14, 04:08 PM   #7
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Yeah,makes no sense.

Most of the time at my clinic I just hook the saddle horn over stand's arm;I only clamp the seatpost if I have to really torque on something. I can't imagine either the stock steel or ti seatpost being damaged from a properly adjusted workstand.
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Old 05-12-14, 04:40 PM   #8
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Thanks for the replies.
Then I assume that when I lower the seatpost as far as possible and clamp the seatpost near the seat tube, it will be no problem to rotate the bike 180 degrees so the bike is upside down.
Btw, my workstand has thick rubber pads inside the clamps which are clean and undamaged. So I think there is no need for a rag or inner tube.
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Old 05-12-14, 04:54 PM   #9
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Quote:
Originally Posted by ThorUSA View Post
so let me get this straight .... if you clamp a 40 lbs or so Brompton with the seatpost, there is danger to damage the frame, but its quite alright to have a 200 lbs guy ride it down the street ....

something has to give .... or better not ...
I imagine that they fear that someone rotates a bike while it is held in the stand such that load, 40 lbs, causes an extended seat tube bend, where as normally it loaded as a column, with a little bending.
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Old 05-12-14, 05:05 PM   #10
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but that is not the case.. 1) they dont weigh 40 pounds . my Touring bike does but it's overbuilt like farm Implements.

and 2) the seat post is at a 72~3 degree angle so the riders weight is levering on that.
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Old 05-12-14, 05:17 PM   #11
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but that is not the case.. 1) they dont weigh 40 pounds . my Touring bike does but it's overbuilt like farm Implements.

and 2) the seat post is at a 72~3 degree angle so the riders weight is levering on that.
Good point, but I can't think of any other reason then.
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Old 05-12-14, 06:02 PM   #12
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Quote:
Originally Posted by fietsbob View Post
but that is not the case.. 1) they dont weigh 40 pounds . my Touring bike does but it's overbuilt like farm Implements.

and 2) the seat post is at a 72~3 degree angle so the riders weight is levering on that.

:-) a little sarcasm about the weight ...

sure there are MUCH greater weights when somebody rides the bike than the bike alone in a workstand, even if you rotate it...

I would NEVER clamp a bike on one of its tubes... no matter how heavy the gaspipes are ..... well maybe with a Raleigh 20 ... lol
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Old 05-12-14, 06:08 PM   #13
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Good point, but I can't think of any other reason then.
Could it be that they are afraid that too much force is applied when you loosen or tighten the wheel nuts for instance with a torque wrench ? In that case there is of course a rather high lever on the seat post/seat tube junction. If so it would be better to apply the final torque with the bike standing on the floor.

Last edited by Rijnton; 05-12-14 at 06:12 PM.
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Old 05-12-14, 08:23 PM   #14
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Could it be that they are afraid that too much force is applied when you loosen or tighten the wheel nuts for instance with a torque wrench ? In that case there is of course a rather high lever on the seat post/seat tube junction. If so it would be better to apply the final torque with the bike standing on the floor.
so whats the torque on them wheelnuts ? Most of mine have quick releases ... :-0
maybe 16 kg ?

I am having fun with this
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Old 05-12-14, 09:36 PM   #15
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Any bike other than a gas pipe special - I never clamp a frame tube. Never. Good way to ruin things. Lot easier to replace a seatpost than a frame tube or a complete frame.

As for a rag, it allows me to clamp the Brommie seatpost a little less than if it weren't there, thereby (hopefully) exercising less pressure on the seatpost itself as well as preventing injury from the clamp jaws.
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Old 05-13-14, 05:47 AM   #16
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If you have a nice (telescoping) seat post that you are worried about, get a cheap steel one to use just for this purpose (where you put it in almost all the way and clamp just above the frame).
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Old 05-13-14, 06:23 AM   #17
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Maybe they are worried that you are one of those guys with sheer dumb gorilla biceps and shovels for hands, and tightening the hell out of the work stand, and just before the clamp snaps, the seatpost is squeezed a tad off round, ruining the ability to shove the seatpost fully down.

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Old 05-13-14, 06:29 AM   #18
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maybe they are worried that you are one of those guys with sheer dumb gorilla biceps and shovels for hands, and tightening the hell out of the work stand, and just before the clamp snaps, the seatpost is squeezed a tad off round, ruining the ability to shove the seatpost fully down.

lol
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Old 05-13-14, 07:45 AM   #19
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& better to ruin the top foot than the rest of the Post ..
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Old 05-13-14, 08:13 AM   #20
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Quote:
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Maybe they are worried that you are one of those guys with sheer dumb gorilla biceps and shovels for hands, and tightening the hell out of the work stand, and just before the clamp snaps, the seatpost is squeezed a tad off round, ruining the ability to shove the seatpost fully down.

wasnt there a commercial somewhere :

working on a Brompton .............20 dlr
buying an extra seatpost to clamp it without fear to destroy the original one...... 50 dlr
clamping the frame instead and scratch or bend it...... priceless
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Old 05-13-14, 10:55 AM   #21
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... I just hook the saddle horn over stand's arm;...
This.

All I need is to keep the bike at a good height so that I can work on it while I'm standing upright and to allow the wheels and crank to spin. Even if I had to torque something down it doesn't involve such a great amount of force that I have to clamp the bike onto something solid and use both hands on a breaker bar.
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