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Old March 11th 10, 01:48 AM posted to rec.bicycles.tech
Peter Meilstrup
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Posts: 21
Default 6'6" beginner rider wonders: 62cm or 64cm Trek frame?

On Mar 10, 12:32*pm, SMS wrote:
Kyle Bramblesglarb wrote:
I'm a tall beginner rider preparing to buy my 1st road bike. *I've
begun training for a century ride on my Trek 5400 MTB while I shop for
something faster.


I'm considering a Trek 1-series and for 2010 they offer a 64cm frame
in the Trek 1.5 bike. *I was wondering if anybody could let me know if
the 64cm would make a noticable difference over the 62cm frame. *I may
not be able to justify the increased cost and may end up just getting
a Trek 1.1, but I'm concerned about comfort and getting sore on long
rides. *If starting with a larger frame would make a big difference,
I'll try justifying the additional expense.


I'm also wondering how much better the Tigara shifters are over Sora
and 2300's. *I know veteran riders can tell the difference, but my
last road bike was a Schwinn in 1989... would I be able to tell?


You're already doomed with the choices you've presented.

You should be getting something with a true 64 or 65 cm frame, i.e. like
something based on the Rivendell A. Homer Hilsen frame.

Alas, most of these large frame bicycles are going to cost you a
fortune. With the curse of compact frames, a 64 cm frame is not really a
64 cm frame anymore.

At least get a true 62 cm frame, like the Jamis Aurora.


Augh! With a 72 degree seat tube and 59cm top tube the Jamis has 2.5cm
less reach than the Trek. Additionally, the top of its head tube is
fully 6cm lower!

I don't understand why people fetishize the height of the seat
cluster. Seeing as how the seat post extension has a wider range of
adjustment than any other bicycle component, seat tube length is quite
possibly the least relevant piece of information you can have about a
bike frame. Its last relevance was in the days of level top tubes,
when it happened to also determine the height of the top of the head
tube.

Don't fall into the trap of thinking that because old bikes had level
top tubes and were made in decent sizes, that a currently produced
level top tube bike will be better than one with a sloping top tube.
In this case it led to a recommendation of a bike that's 3 sizes too
small instead of just 1.

The most important parameters of bike frame size are (1) how high the
top of the head tube is above the bottom bracket and (2) how far
forward the head tube is in front of the bottom bracket. Taken
together these two parameters determine where you can put the
handlebars in relation to the feet.

In days of yore we measured these parameters indirectly via the seat
tube length and top tube length, and riders who prefer a particular
fore-aft saddle position had to mentally adjust the top tube length
when comparing two frames with differing seat tube angles (holding top
tube length constant, a shallower seat angle robs the frame of reach,
as you end up sliding the saddle forward to compensate.) Nowadays with
varying top tube angles the seat tube can no longer masquerade as an
indicator of head tube height, so the tables list some mishmash of
"effective" tube lengths and you have to do a bunch of trigonometry to
compare between brands.

It might be better to just measure (1) and (2) directly -- this is
called "stack" and "reach" and a few manufacturers list it, including
Trek.

Compact geometry ought to have been a boon for most riders, allowing a
higher handlebar placement than traditional race fit. I think it does
help shorter riders (who are a larger proportion of the underserved
riding public than us tall guys.) However it also coincided with a
development in racer fashion of riding with a very deep saddle-bar
drop and using the "hoods" as primary hand position. So everyone now
rides on frames that are a size or two too small, level top tube or
no. Tall people who remember when bike frames were made large seem to
misattribute the cause and blame sloping top tubes for their woes.

Also, in those
large frame sizes, you should think about steel, not aluminum. As others
in this thread have stated, you start to have frame cracking issues with
aluminum in bad places.

Ironically, there are some true 64cm bikes from Bikes Direct, in steel
or aluminum i.e.
"http://bikesdirect.com/products/mercier/mercier_serpensIX.htm"
"http://www.bikesdirect.com/products/motobecane/sprint_x.htm"
"http://www.bikesdirect.com/products/mercier/mercier_corvus.htm"


These have a reasonable amount of reach, particularly the aluminum
one.

Peter
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