QR seat clamp
 

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[Closed] QR seat clamp

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The One Where Cougar Ventures Into The Bike Forum, the first in an occasional series.

At the behest of the rest of the household, I've stuck an otherwise unused bike in an otherwise unused turbo trainer. I was expecting it to be used once and then just take up space, but it's probably done more miles since I set it up two days ago than it has in its life (which isn't saying much).

Now I'm eyeing it up. It's just right on the edge of being small enough for the smallest rider, and the seatpost is about six metres long so it's easily adjustable to accommodate my towering 5'10" frame. But the seat clamp is an Allen bolt and it's already winding me up. So I want to fit a QR. Two questions:

1) Am I right in thinking the sizing is the outside diameter of the seat tube? Seatpost is labelled 27.2mm so that's a 28.whatever clamp, yes?

2) It's a long time since I last bought any bike bits beyond an inner tube. Clamps range from like £3 up to the GDP of a small African country. What am I gaining if anything over say a £25 Hope over a £5 Brand-X? I don't give a damn about bling, the bike has seen outside once in like ten years and that was only because I moved house, but I don't want something made of cheese that's either gonna snap or never quite lock properly and just piss me off.


 
Posted : 17/02/2021 8:25 pm
 igm
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Yep outside of seat tube. And that’ll be different for different frame materials and tubes and designs (1990s shimmed Orange seat tubes anyone?) even if it’s a 27.2 seat post in all of them.

Buy the cheapest decent quality looking one.


 
Posted : 17/02/2021 8:30 pm
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Yep outside of seat tube.

Perfect, thank you.

Buy the cheapest decent quality looking one.

That... is less helpful because it was kind of what I was asking. How do I know what quality looks like? Should I give Brand-X a swerve, the next-cheapest brand I've heard of I think is Box at ~£15 ish, does that sound sensible?


 
Posted : 17/02/2021 8:36 pm
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What size do you need?
I have a bunch, if any fit happy to post over to you.
vmgscot

PS - I think we met on a White Room trip a few years back?


 
Posted : 17/02/2021 8:40 pm
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Just look at the reviews, that should give you a good indication.
Something like Hope might feel nicer in the hand (bear in mind you'll be pushing quite hard with the heel of your hand), but most are pretty good


 
Posted : 17/02/2021 8:41 pm
 igm
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That… is less helpful because it was kind of what I was asking.

Sorry. That BrandX one at Wiggle meets my criteria for looks decent quality. Aluminium with brass bush. Fine.

PS £4.39 when I look at it.


 
Posted : 17/02/2021 8:47 pm
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What size do you need?
I have a bunch, if any fit happy to post over to you.

Oh! That's very kind of you. Thank you. Do you want me to cover postage or shove a few quid in a charity or something?

As above, it's a 28.whatever I believe (28.6?), the seatpost is marked 27.2 and it's a steel frame. The bike is a Surly Cross Check.

PS – I think we met on a White Room trip a few years back?

I fear you may have me confused with someone else, sorry.


 
Posted : 17/02/2021 8:47 pm
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That BrandX one at Wiggle meets my criteria for looks decent quality. Aluminium with brass bush. Fine.

👍 cool. Tar.

Kinda annoying paying three quid postage for a five pound part when I placed an order with them yesterday which together would've netted me free delivery...!


 
Posted : 17/02/2021 8:49 pm
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Argh.. sorry, just realised I passed the clamps on to a bike rebuilding charity in Glasgow with all the other spare parts I donated. Apologies.


 
Posted : 17/02/2021 9:16 pm
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Pants.

Thanks for the thought, anyway.


 
Posted : 17/02/2021 9:57 pm
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I think of seat clamps as like tooth paste.

Whilst there is a price difference, it's so small in absolute terms, you might as well get the best.

I had a crappy cheap one, always slipping. Got a Hope, no problems anymore.


 
Posted : 18/02/2021 10:56 am
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I'll almost guarantee that you'll be wanting a 30mm (or 29.8) for that frame 😉


 
Posted : 18/02/2021 2:09 pm
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The bike is a Surly Cross Check.

surly say the seat clamp is 30.0mm.


 
Posted : 18/02/2021 2:37 pm
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Oh? Brilliant, thank you.

I'm seeing 28.6mm and 31.8mm as typical sizes. Where do I get one of those from, then?


 
Posted : 18/02/2021 4:06 pm
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... would keeping the existing clamp and fitting a QR skewer in place of the bolt be a better option?

Not that it's massively important on a turbo trainer, but the bolt is also the mounting point for the cantilever brakes if that makes any difference to anything?


 
Posted : 18/02/2021 4:24 pm
 igm
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You might be able to fit a QR bolt but chances are it’ll be pointing in the wrong direction at the right tension.

Equally you might be able to buy a QR clamp with a flat surface under the bush on the lever side. The Brand X one is no good I think as it uses the curved surface of the clamp to seat the lever. The Hope bush does sit on a flat surface but it’s quite a short bolt.

This would probably do it but it’s a plastic bush. https://www.tredz.co.uk/.XLC-QR-Seatpost-Clamp-Colour-PC-L04-_126899.htm?sku=497373&utm_source=google&utm_medium=cpc&utm_campaign=google_shopping&gclid=Cj0KCQiAvbiBBhD-ARIsAGM48bxyf4GXQdsQHBd-MXAsSwQH82_uMXMrUfKR1Ig2Dte4p4JT-FirYTcaAlNvEALw_wcB

If you get one that works you the need to drill the thread out of the existing clamp so the bolt goes straight through to the nut from the new clamp.

And the bolt has to be the right length and diameter.

In short, yes you can, but probably no you shouldn’t.


 
Posted : 18/02/2021 6:27 pm
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I'm glad I asked now. Jesus christ, why is nothing ever simple?


 
Posted : 18/02/2021 8:11 pm
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As its only for indoors. Could you glue an Allen key into the bolt. Or replace it with a butterfly bolt. Probably both bad ideas.


 
Posted : 18/02/2021 8:27 pm
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I've got 30mm Salsa QR one which I'm sure is STW approved.
It's not perfect condition, so happy to post out for nothing if you throw a few quid at a charity?

I've got a larger Hope one on a Orange P7, it's shit. The reaction point for the QR is too far from the frame, QR has to be awfully tight to avoid the post slipping.


 
Posted : 18/02/2021 8:52 pm
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Brilliant, thank you. Name your charity.


 
Posted : 18/02/2021 10:37 pm
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Let's go for Mind. Fairly appropriate in the current circumstances.

PM me and I'll get some images across to make sure you're happy with it, then hopefully post it out tomorrow all being well.


 
Posted : 18/02/2021 11:39 pm
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Oof. Yeah, sure, happy to.


 
Posted : 18/02/2021 11:54 pm
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Thrown ten quid at them.

Which it seems to have taken twice.

Ho hum.


 
Posted : 19/02/2021 12:00 am
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Just to close off this exciting tale,

The esteemed @R.lepecha sent me a 30mm QR, it arrived yesterday and I've just installed it. Fits like a glove (if you only have one finger).

Awesome. Thank you all.


 
Posted : 23/02/2021 8:55 pm

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