What seat post clamp?

[Tom Crispin]

I want to order online a QR seatpost clamp for a bike I won't see
until Monday. I know the diameter is less than 31.8mm because I have
a couple of clamps that size spare and they don't fit.

The frame is described as 7005-T6. Can I tell from that if I should
order a 30mm clamp or 28.6mm clamp? Or will I have to wait until
Monday when I can measure the diameter?

 

[Rob Morley]

In article <[email protected]>, Tom Crispin
[email protected]e says...
> I want to order online a QR seatpost clamp for a bike I won't see
> until Monday. I know the diameter is less than 31.8mm because I have
> a couple of clamps that size spare and they don't fit.
>
> The frame is described as 7005-T6. Can I tell from that if I should
> order a 30mm clamp or 28.6mm clamp? Or will I have to wait until
> Monday when I can measure the diameter?
>
Wait until Monday and wrap a bit of tin around it until a 31.8mm clamp
fits.

 

[Pete Biggs]

Tom Crispin wrote:
> I want to order online a QR seatpost clamp for a bike I won't see
> until Monday. I know the diameter is less than 31.8mm because I have
> a couple of clamps that size spare and they don't fit.
>
> The frame is described as 7005-T6. Can I tell from that if I should
> order a 30mm clamp or 28.6mm clamp? Or will I have to wait until
> Monday when I can measure the diameter?

Sorry I don't know - but I'm wondering if there really is a 30mm standard -
or if that is a round-up euphemism for 28.6mm, just as "32mm" is for 31.8mm?

~PB

 

[Tom Crispin]

On Sat, 16 Feb 2008 15:12:32 -0000, "Pete Biggs"
<[email protected]> wrote:

>Tom Crispin wrote:
>> I want to order online a QR seatpost clamp for a bike I won't see
>> until Monday. I know the diameter is less than 31.8mm because I have
>> a couple of clamps that size spare and they don't fit.
>>
>> The frame is described as 7005-T6. Can I tell from that if I should
>> order a 30mm clamp or 28.6mm clamp? Or will I have to wait until
>> Monday when I can measure the diameter?
>
>Sorry I don't know - but I'm wondering if there really is a 30mm standard -
>or if that is a round-up euphemism for 28.6mm, just as "32mm" is for 31.8mm?

www.chainreactioncycles.com/Models.aspx?ModelID=15692

 

[Pete Biggs]

Tom Crispin wrote:

>>> I want to order online a QR seatpost clamp for a bike I won't see
>>> until Monday. I know the diameter is less than 31.8mm because I
>>> have a couple of clamps that size spare and they don't fit.
>>>
>>> The frame is described as 7005-T6. Can I tell from that if I should
>>> order a 30mm clamp or 28.6mm clamp? Or will I have to wait until
>>> Monday when I can measure the diameter?
>>
>> Sorry I don't know - but I'm wondering if there really is a 30mm
>> standard - or if that is a round-up euphemism for 28.6mm, just as
>> "32mm" is for 31.8mm?
>
> www.chainreactioncycles.com/Models.aspx?ModelID=15692

I should have known that. Sorry I didn't check.

~PB

 

[M-gineering]

Pete Biggs wrote:

>
> Sorry I don't know - but I'm wondering if there really is a 30mm standard -
> or if that is a round-up euphemism for 28.6mm, just as "32mm" is for 31.8mm?
>
> ~PB
>
>

30mm is the size for externaly butted steel seattubes

--
/Marten

info(apestaartje)m-gineering(punt)nl

 

[Tom Crispin]

On Sun, 17 Feb 2008 11:14:08 +0100, M-gineering
<[email protected]> wrote:

>Pete Biggs wrote:
>
>>
>> Sorry I don't know - but I'm wondering if there really is a 30mm standard -
>> or if that is a round-up euphemism for 28.6mm, just as "32mm" is for 31.8mm?
>>
>> ~PB
>>
>>
>
>30mm is the size for externaly butted steel seattubes

So 28.6 it is. Still, just to be on the safe side, I'll wait until
tomorrow before ordering.

 

[Jeremy Parker]

"Tom Crispin" <[email protected]> wrote

snip]

> The frame is described as 7005-T6. Can I tell from that if I
> should
> order a 30mm clamp or 28.6mm clamp?

7005 tells you what alloy the aluminium is, but I don't know the
virtues of different alloys. My Grumman canoe is made our of 6061.

T6 tells you how the alloy has been heat treated. My canoe is also
T6. T6 canoes seem to cost a bit more than T4 canoes, but I don't
know why.

Anyway, it doesn't tell you about seat post diameters.

Seat post diameters are really inch sizes. Thus 28.6 is really 1-1/8
inches, 30, 1-3/16 inches. "Zen and the Art of Motorcycle
Maintenance" has a good section explaining that the best shim stock
in the world for adapting sizes is made from old beer cans, but you
have to scrape the picture off the beer can to maintain the bike's
artistic purity

Jeremy Parker