Sandy said:Mark Hickey <[email hidden]> a réfléchi, et puis a déclaré :
Quoted message said:Quoted message said:Quoted message said:http://www.merida.com/s0_global/main_control.php?group0=tech&group1=flexstay
Quoted message said:Quoted message said:It probably requires plenty of snake oil to prevent squeaks! ;-)
If those round stays are flexing as much as they claim, that would be
one SCARY bike to ride, IMHO. I can't imagine mounting V-brakes on a
seat stay that could flex enough to move the dropout (axle) "several
mm's". It'd be like riding a bucking broco.
Given your experience with manufacturers, I am surprised you have never
observed flex testing of frames and forks.
I have seen them. I've just never seen anyone flex a "solid" rear
triangle up and down a few mm's (well, more than ONCE, that is). ;-)
My point is that the claims that are made for that frame seem to be
dubious, unless they're really NOT round stays, but flat metal strips
surrounded by flexible tubes.
Quoted message said:If you can get a chance,
unlikely as it may be, LOOK has a fork testing apparatus. It holds the
pivot at the crown, and the legs are bent backwards up to a centimeter, for
hundreds of thousands of cycles. Décathlon tours its stores with the frame
flex machine, which twists, akternately, the head tube and the rear
triangle, for as much as a centimeter (so I recall), for hundreds of
thousands of cycles.
Twisting is one thing. I can twist my frame in a hard uphill sprint.
That's been discussed here to death, and there are plenty of sprint
photos to back up the fact that this happens on real bikes ridden by
real riders.
But there's virtually nothing short of tossing it under a truck that's
going to find 3mm of "vertical travel" in the rear end. Try it on
your own frame. Take a static meaurement and then load 400 (or heck,
800) pounds on the saddle and measure again (seat tube top to
dropout). If you measure a 3mm+ delta, you've either got a suspension
frame or a broken frame.
Quoted message said:Quoted message said:It might be fun to go to a retailer and ask 'em if you could see what
it feels like to flex the dropouts up 3mm though. They might get
suspicious when you show up with a hydraulic press to do it though.
And that's exactly the kind of test bed they use.
Two manufacturers of top pro equipment. It's a shame they don't know what
they're doing as well as you do. Maybe you could write to them and advise
...
You're missing the point - I'm not sure if it's on purpose, or if you
just don't understand why a test that requires a hydraulic press to
deform a frame just MIGHTnot have a whole lot of connection with the
"real world ride performance".
Or not - when you consider some of the silly things that DO sell,
there's gotta be a lot of people who buy into that kind of thing.
Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $795 ti frame