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Query re seatpost


RodTi
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Since today seems to be the day for silly questions...

 

Here goes...

 

Just how big a difference does ,2 of a mm make with regards to seatpost sizing?

 

Thanks to a fellow hubber, I tried my luck with a 26,8 seatpost on my 27,0 bike.

 

And it fits.

Well.

As in - you have to twist it left and right to work it in deeper, or pull it out.

It occasionally slips down after a rocky descent, but not so much that I notice it while riding, but only when I get off, and see that my marker line has shifted.

 

I am a heavy rider though - so this is probably to be expected.

 

Point though, is that my bike is old - and only source of information is on the web.

Numerous sites confirm it to be a 27,0.

People who own the same frames confirm it to be a 27,0.

But the Thompson Elite very clearly states that it is a 26,8.

 

Now yes - the quickest way to settle this, would be to go home, load the bike in the car, and then schlepp off to a different lbs in a different town, which might actually have one of those thingies that measures the width.

 

But I haven't yet remembered to do that.

So I thought I'd try my luck here.

 

A 27,2 seatpost is definitely too big.

 

Is it possible that the 26,8 is too small, and yet the ,2mm deviation is so insignificant that the seatpost fits well enough so as not to shift around?

Would this then mean that a 27,0 would fit even snugger?

 

Should see some interesting answers to this.

Or none at all.

 

Such is life.

 

Ta Big%20smile

 
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I also could not get the exact size post for my bike . And went the -2 route . Works perfectly . Does not even go down .

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It slips down becuse it has to be 27.0 mm. To make the 26.8 fit tightly you are probably over tightening it.

 

Get a 27.0 mm seatpost
HANSIE SLIM2007-07-24 08:35:01
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Yeah, but like someone else said today DR, you have to be careful not to fall through your own poepol you're so maer!

 

Erm, regarding the OP, sorry can't help!!
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Yeah' date=' but like someone else said today DR, you have to be careful not to fall through your own poepol you're so maer![/quote']

 

Thanks hey, now I'm only SOMEONE!!! Angry

 

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MichH - was thinking the same about what ewep said but I aint talking to or about DR at the moment cause he said my bike is ugly!

 

Have an old Specialized FSR retro I've built up and had the same problem, -2 hasn't given any trouble!

 

HANSIE SLIM - maybe 'Get a 17.0 mm seatpost' not so slim?

 

 

 
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Hehehehe, ewep, I was trying not to remind him who it was who said it in case it got you into more trouble!!

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I'll get the right size. I rode a 27.0 seatpost in a 27.2 frame...and well I f uped the frame.

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Not to worry . I will not feel save going around in circles at the Tswane race ! Will be witing for him !

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It slips down becuse it has to be 27.0 mm. To make the 26.8 fit tightly you are probably over tightening it.

 

Get a 17.0 mm seatpost

 

Ja.

That might be.

And I suspect I am way heavier that Dirt-rider, who apparently does amazing biological feats by falling through himself LOL...

 

Seriously though - how easy is it to overtighten a seatpost with a cheap old quick-release?
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Rode it for a year with the 27.0 seatpost, but it kept slipping. I broke two clamps in the process. When I replaced the post with a 27.2 the frame cracked just below the clamp.

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ouch . Ok hopefully I will get away with my setup since I get no slip and as you may have gathered don't weigh much over 75

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Mud - don't want to get into semantics here - but what do you mean by slipping?

 

As in every 5 minutes, get off because it's moved say 10cm's?

 

If I adjust mine once/maybe twice in a 3 hour ride, and then because of a gradual shift of about 5 cm's?

 

Hangon - anyone out there who is large to heavy, with a correctly sized seatpost that does NOT slip at all??
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I must add..it happened on a road bike. And I did fool around with it quite a few times and thus I may have weakend the alloy of the frame. if you are worried just use a piece of alloy from a cooldrink can(fanta pref..) around the post, it works great.

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