On 05/20/2016 03:00 PM, masmojo wrote:
I am a diehard canti. guy, but I do have a few bikes with mechanical disk brakes.
While Grants observations are correct, there are trade offs; I have recently been
looking at going tubeless on a build and I've noticed some things, first most
tubeless/ disk specific wheels rarely have more than 32 spoke & many have 28!
It stands to reason that while a disk brake may require a stouter frame, a rim
brake is going to ideally need a stouter wheel.
How do you figure that? As Rich Lesnik said here the other day,
"A front disc-brake wheel is heavily dished (uneven spoke tension,
left to right). The proximity of the braking surface to the hub
increases the stress on the pulling spokes, relieving the "pushing"
spokes -- the flex on the looser-side spokes can work-harden the
bend in the spoke elbow at the hub, and it will eventually break.
Same thing with the rear wheel (only here the lower-tension spokes
are on the non-drive, left side). These spokes are already prone to
breaking over the long haul, as they flex more, and will work-harden
more quickly. This increased stress would still be problematic on a
non-dished disc-brake front wheel, as well, because of the increased
stress all around, at the hub. Admittedly, replacing a broken spoke
is easier, and less costly, than replacing a worn rim. Nonetheless,
a dished front wheel presents additional problems -- as the primary
braking instrument, the front wheel, when unevenly tensioned (side
to side), can, under severe stopping conditions, become unstable,
provoke an accident, or even "figure-8". Not good."
And Rich is a very highly respected wheel builder, the very top of the
heap in Rivendell-world. And I can add some anecdotal evidence to this:
a guy in our bike club bought a disc-equipped Trek
kinda-sorta-touring-bike last year, the one made for those proprietary
"dry bags" that mount on a proprietary rack on the front fork. Since
he's had the bike, he's broken spokes in both the front and rear
wheels. Other than this, I'm not sure I can recall a single front
wheel I've ever seen that's broken spokes.
Now simple engineering dictates that less rolling weight is preferable to
sprung weight, so theoretically, moving the strength/additional weight to the
frame should result in faster, better accerating, lively handling bike!
Unless you're talking about a suspension bike, there is no "sprung
weight," is there? And in the suspension world, it's between sprung
weight and unsprung weight, with the former being greatly preferred.
Now are the differences noticeable by the average rider?? That remains to be
seen
The average rider will most certainly notice broken spokes.
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