Velo Orange Grand Cru Seatpost.

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pwa
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Re: Velo Orange Grand Cru Seatpost.

Post by pwa »

FatLad1980 wrote:
pwa wrote:
FatLad1980 wrote:
As the seatpost is only 300 long it won’t quite go to the Q. Probably only as far as the 30cm mark ;)


When I install a seatpost that is longer than it needs to be I cut it to size. And in your pic I would normally be aiming for about the 31cm mark. But I am conservative, and I would be content with the 30cm mark. I reckon that more or less replicates where the minimum insertion mark is likely to be. The worst case scenario is that you have a bit of the minimum insertion mark showing at the collar.

EDIT Actually, as these posts have 23cm above the min insert line, you can clearly see that 23cm is below the collar by a good margin, so no problems.


I’m more concerned about damaging the frame due to the post being too short.

I normally aim for 10cm, which is conservative. I reckon you might get 9 or thereabouts, which is still a decent amount.
PH
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Re: Velo Orange Grand Cru Seatpost.

Post by PH »

Brucey wrote:FWIW I think it is an excellent idea to have a good deal more than the stipulated minimum inside a frame, especially when you are using a long seat pin inside a big frame. Chances are that if the rider is upscaled everywhere, not only will there be more leverage but there will be more weight too.

Thus depending on the frame design, I'd want 3-4" of the seat pin inside the frame, regardless of what is marked on the seat pin itself.

cheers


Is this for the benefit of the frame or the seatpost or both? I notice the OP's main concern is the frame, yet I've not come across this sort of damage to a frame and know of a couple of snapped seatposts, both went flush with the clamp.
Brucey
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Re: Velo Orange Grand Cru Seatpost.

Post by Brucey »

it is for the benefit of the frame. The bending moment in the seat pin near the collar is the same, so it is pretty much just as likely to fatigue (if there is a given amount sticking out the top) regardless of whether there is a good amount of insertion with a long one or not.

I have seen several frames break where the seat pin wasn't in very far; to a first approximation (in a typically loose-fitting frame) the seat pin sees a cantilever loading where there are two loaded points and the forces are in inverse proportion to the length of the insertion. If the seat tube is reamed to a good fit, the insertion length matters less.

cheers
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531colin
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Re: Velo Orange Grand Cru Seatpost.

Post by 531colin »

FatLad1980 wrote:Current seat post doesn't have enough setback.......

FatLad1980 wrote:............A friend has suggested I may need to increase the height of my seat post a little after seeing me on the bike. I'll give that a go first before considering finding something else. Doing it by eye he says the bottom of my knee looks like it's pretty much over the pedal axle so it's more likely that I just need a bit more height........


Hmmmmm........Pushing the saddle back will move it further away from the pedals, just as surely as raising the saddle, but other than that, saddle setback and height are best regarded as separate adjustments, in my view.
Saddle setback is entirely about your balance on the bike; that is how much weight you have on your hands when freewheeling. If you have too much weight on your hands, your saddle needs to go back.
Saddle height is about pedalling efficiency; it needs to be low enough so that you can pedal smoothly at a cadence of 100 on your worst day when you are tired and your legs are stiff, because any higher than that risks hyper-extending your knee at every pedal stroke. The modern thing is to concentrate on having your saddle at a height where you get maximum power from your muscle work, and that happens when your knee is (almost) straight .....so for the few per cent of the time when you are looking for maximum power, you can just slide back in the saddle to get more knee extension. The rest of the time, give your knees an easy life, and you could still be cycling into your eighties.
The current fashion for steep seat tube angles helps normally-(in)flexible people to achieve a racing crouch, but sitting right over the pedals instead of further behind them means its impossible (for many folk) to pedal other than with their toes down and heels up....... so they then raise the saddle yet again in order to get knee extension. This takes you to a position where you can't reach the pedal at the bottom without being on tiptoe.....and this is just one step away from hyper-extending your knees.
PH
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Re: Velo Orange Grand Cru Seatpost.

Post by PH »

Brucey wrote:it is for the benefit of the frame. The bending moment in the seat pin near the collar is the same, so it is pretty much just as likely to fatigue (if there is a given amount sticking out the top) regardless of whether there is a good amount of insertion with a long one or not.
cheers

Cheers, prompted me to go measure my own, all good :wink:
Samuel D
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Re: Velo Orange Grand Cru Seatpost.

Post by Samuel D »

If you return this seatpost, you’ll have to consider what your alternatives are for long setback. Options are not thick on the ground.

I’ve been waiting a long time for Planet X to get new stock of their Holdsworth seatpost that is one of the few that exist. The current arrival date on their site is 22 March, and I don’t know if that’s a computer’s automated guess or a real estimate.
FatLad1980
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Re: Velo Orange Grand Cru Seatpost.

Post by FatLad1980 »

The reason for looking for extra setback was I felt my knee wasn't over the centre of the pedal axle whilst in the 3 o clock position.

A friend viewed from the side and said it was pretty much there. He suggested the seat could go a fraction higher due to there maybe being too much bend in the knee at the 6 o clock position.
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