cyberbellum said:* Agreed. I was thinking of drilling down low, directly
into the hub body where the lockring is. Don't know if
there is much metal there, though. The bearings are in the
way. Also, I wouldn't want to do this with a nice hub and
sprocket.
The only function of the lockring is to keep the cog from
unscrewing, but the shallow threading makes that quite
difficult without huge axial forces. The screws wouldn't
need to be very big because they would be very efficient
at keeping the cog from unscrewing.
Dave, have you tried red locktite? Seems extreme but then
again so is a mechanically-inspired fall from a giraffe. *
On the wheel with less-expensive components (Suzue basic,
Sem sprocket, Surly lockring), I used red loctite on both
sprocket and lockring. I got up on the giraffe and stopped
the wheel in place against the porch, and bounced on the
front pedal to tighten the sprocket. Then I put on the
lockring and stood on the wrench (about 200 ft-pounds) to
tighten it (risky but I was careful). This approach seems to
have worked because we tested it and the rider has used it
for months now.
On the second wheel with more expensive components (Suzue
ProMax hub, EAI sprocket, and Surly lockring) I used
grease on the sprocket and red loctite on the lockring. I
used basically the same approach to tighten things. We
have slippage.
The easy conclusion to come to is "Duh - use red loctite on
both and you're all set; not only that but you don't need to
use more expensive components". However, that really doesn't
address the basic design considerations:
1. Have a strong hub where the axle will not bend under
vigorous use. The 3/8" axle is not sufficient.
2. Be able to change sprockets at will with a minimum amount
of fuss. The red loctite and risky tightening procedure
are not acceptable for a good solution.
3. Be able to service the wheel (i.e., change spokes, even
rebuild the wheel) like a normal hub. This eliminates the
use of red loctite, welding, and similar approaches.
4. Have a high-reliability, secure connection. A solution
that depends on loctite isn't a solution, it's a patch.
More like using advanced chewing gum.
5. Make use of high-quality components to ensure a smooth,
non-binding pedal action. We're ok there with the track
solution; everyone that has tried either wheel has
commented on how extremely smooth it is.
So a stock Torker or similar basically handles only 4. The
track hub solution handles 5, and marginally 4, but nothing
else. unisk8r's solution handles 2, 4, and 5. The standard
Sem solution handles 4 and 5 (based on one I just
delivered). I am working on a solution that handles 1, 2, 3,
4, and 5, but I'm not free to discuss it yet.
The other nice thing about unisk8r's solution is that it
allows one easily to match the top and bottom gears, since
they are drawn from the same parts pool. It is also easy to
"gear down" the unicycle. The disadvantage of that is that
they are drawn from the same parts pool, so it would be
harder to "gear up" the unicycle. The wheel seen in my photo
uses the smallest possible chainwheel on top with the
largest possible track sprocket on the bottom, which
achieves very close to 1:1. From there it is easy to gear
up, but not possible to gear down.
I have had requests to gear up, but none to gear down.
However, unicycling is quite dynamic these days.
Exciting, isn't it?
--
U-Turn - Member of Generation XO
Weep in the dojo... laugh on the battlefield.
'29er Tire Study' (u-turn.unicyclist.com29erTireStudyOpen ↗)
'Strongest Coker Wheel in the World'
(unicyclist.comalbup39Open ↗)
'New York Unicycle Club' (newyorkunicycle.comnewyorkunicycle.comOpen ↗)
-- Dave Stockton
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