On Mon, 2013-04-15 at 22:06 -0700, Cyclofiend Jim wrote: > Thanks for bringing up those points, Jan - I'm not specifically > against freewheels. My experience was that I regularly bent axles on > my old mtb which had a freewheel and never had that problem with any > freehubs. My recollection was that the mtb (which was a six speed > 1983 drivetrain) had narrower cones than my XT and DuraAce freehubs. > But again, no data to back that up.
That's not the only, or even the worst, problem with freewheels. By design, pedaling tightens a freewheel. On a tandem or on a bike ridden by a very strong rider, they get screwed on so tight it's difficult if not outright impossible to remove them. What's more, the tremendous force needed (we're talking about six foot cheater bars here, no exaggeration) is channeled through a couple of small notches or a handful of splines, which readily strip out. > > And I guess the point I was really trying to make stemmed from your > comment about the loss of tooling, expertise and the necessary > economies of scale involved in making a quality freewheel today. > Since most of the bicycle market probably is less likely to support > it, it seems freewheel production isn't likely to increase. But since > there are plenty of freehubs around, why not continue to let them make > the ratchety bits and focus on making something that is not designed > to shift in a crosswind. Okay, that's overstating it, but it seems to > me that creating a longer-toothed cassette of longer-wearing material > might be a simpler option. > > I just recall walking into the old shops and looking at the cog board > in the back. It seems like it should be comparatively easy to come up > with a similar solution. That assumes there's actually a market for straight-cut sprockets. Even back in the 1970s they were actively searching for tooth profiles that made shifting easier. Remember Shimano's wavy teeth? I doubt the total market for such cassettes in this country would even be as large as the readership of this google group. > Though I'm ignorant of any constraints which are in place for makers > having to license the interface spline from Shimano. > > - Jim / cyclofiend.com > > > > On Monday, April 15, 2013 8:43:36 AM UTC-7, Jan Heine wrote: > The bearings spacing on most cassette hubs is no different > from that of a freewheel hub. With the exception of Shimano > and Mavic and a few small makers, all freehubs have the hub > bearings under the flanges, more or less. As long as the axle > is properly designed, that is not a problem. > > The problem with most freewheel hubs were the thin axles. They > were designed for 4-speed and 115 mm spacing. With that short > overhang, no problem. Then they added another 5 mm on the > drive-side for 5-speed, and it was getting marginal. Then they > added another 6 mm to use 6-speed, and the design no longer > worked. They now had more than twice the lever as before, yet > kept the diameter of the axle the same. It's surprising that > it worked as well as it did! > > Adding grooves in the axle on both sides made the problem > worse. (Who needs to adjust their hub on both sides? Maxi put > the grooves on the non-drive side only, so you adjusted only > that side.) > > There are plenty of freewheel hubs that don't break axles. > Don't conclude from a poor execution that the entire concept > is flawed. Cassette hubs have their own design problems. The > biggest one is that the bearings under the cassette have to be > relatively small. > > Jan Heine > Editor > Bicycle Quarterly > http://www.bikequarterly.com > > Follow our blog at http://janheine.wordpress.com/ > > On Sunday, April 14, 2013 11:22:59 PM UTC-7, Cyclofiend Jim > wrote: > > But, I'm not real keen on going back to the narrow > bearing spacing from the freewheel days. (Bent waaay > too many axles back then.) -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en-US. For more options, visit https://groups.google.com/groups/opt_out.
