Daniel Parry wrote:
> In article <
[email protected]>, Pete Biggs wrote:
>> Chris Boardman had a bike made like that for aerodynamic reasons - but it's not practical for
>> normal cycling for us mere mortals. It's very important that seat height is adjustable because:
>> 1) The builder probably wouldn't get it _exactly_ right for you in the first place, first
>> time (a couple of mm does make a difference).
>
> Ok, fair enough but am I right in saying a decent builder could build to within 1-2 mm?
Yes I suppose so if the customer was sure about what they needed.
> I think my argument now rests on the assumption that you could design a saddle attachment that
> would allow (say) 6mm of height adjustment, without the need for seat post / seat tube overlap. I
> would argue that if this were possible it would be sufficient to deal with clothing height
> alterations.
What form would the attachment take? It would be quite difficult to better the simple design of
a seatpost.
> As for variation in saddle heights, perhaps it would be possible, if you're going for a custom
> built bike, to know which saddle you are happy with and be prepared to stick with that model or
> similar whilst using the bike?
Many people do always stick with the same saddle, but that still leaves plenty who would want the
freedom to change model - even if they had a custom made bike.
>> I'm not sure. Tubing might have to be more oversized and/or thickened.
>
> Is seat post tubing thicker / stronger than seat tube tubing?
Very much so (with conventional diamond frames at least). Usually, much, much thicker and stronger
because it's supported only at one end. The seat tube is part of a triangle so doesn't have to be so
strong. Some frame tube walls are hardly thicker than those of a Coke can. You wouln't want to perch
on a pole of that, would you.
> Does the fact that you have only one tube mean you can get away with a weaker tubing
No, the opposite.
> or does the tubing overlap of the seat post add strength?
Yes.
>> Good sensible seatposts rarely snap, and I would be worried about the seat tube snapping just as
>> much or more than about a seatpost.
>
> Even a good sensible seat tube? ^_-
I wouldn't worry if the special seat tube was as strong as a conventional arrangement but I bet that
would then be (almost) as heavy!
>> Adjustabity is being taken away from us enoug as it is (think ahead stems)
>
> Never used one. I take it you mean adjustability of height of them?
Yes.
> Need to use spacers etc. Fact is, many people use them despite this difficulty for some reason -
> weight perhaps?
Because that's what we're being fed by the manufacturers - we're getting less and less choice about
over matter: look what new bikes come with now. The threadless system is cheaper* with more choice
of stems & headsets on the aftermarket now - as well as arguably being lighter and stiffer.
I like some aspects of it a lot, but adjusting height is defintely extra hassle - so much so that
many users never adjust at all, and some are even put off cycling for good because they have the
wrong height bars and don't think they can do anything about it. (Fork steerers being cut too short
is part of the problem as well: often stem at maximum height is simply too low).
* Cheaper and easier for the manufacturer because stems and headsets are simpler, forks don't need
threading, etc.
> Not so different from my idea then?
No indeed, except I'm not convinced that there would be enough advantage in the idea to justify it
for anyone other than specialist competition cyclists. I seriously do not want to loose any more
adjustability so I hope your idea never catches on.
>> However, I wouldn't mind if someone could come up with a design to make seatposts (even) easier
>> to adjust and centre (I hate having to rely on eyeballs).
>
> Vertical lines drawn along seat post?
That would help! Cheers.
--
~PB FA: 62cm Ti frame:
http://tinyurl.com/6stt
Adjustabity is being taken away from us enoug as
