ulyssesnitrate9 said:Hey Flaviu, I was kind of curious what the benefit(s) of having a sealed
cartridge BB would be as opposed to a normal unsealed one? I can't
even tell if mine is currently sealed or not, because the bike shop guy
asked if I wanted sealed put in last time and I said go ahead, but I
never got a bill for it.
Also, I've now noticed my chain becomes loose only when the cranks are
horizontal, but specifically only when the right pedal is back and the
left one forward. Any ideas?
Thanks for your help!
ulyssesnitrate9,
Is it a QU-AX giraffe that you have?
First, read here (between the lines) about the Bottom Bracket (BB)...
It's good to know some basic things about main components 🙂
Giraffe unicycles use a transmission system similar to fixed gear
bikes. The difference is that the first use low quality / cheap
components for the task.
The BB of most giraffes (including yours) is the loose bearings, axle
and cups concept! This was manly designed for forward pedaling only and
is poor quality realized!
When you idle you turn the pedals back and forth. The phenomenon called
-precession- leads to the BB cones being cyclically tightened /
un-tightened. This obviously will work them loose sooner or later!
http://en.wikipedia.org/wiki/Precession
OK, to prevent this you either have it reinstalled with -Blue Loctite-
by a wise mechanic or much better upgrade it to a cartridge BB!!!
The cartridge BB (as you could see in the first link...) consists of
one closed unit which contains the axle and the bearings!!! The only
thing you need to do is secure it well in the frame's BB shell. This
should last very much!
You can find pretty good cartridge BBs for low money now...10-15EU!
I got a Shimano BB-UN26 (10EU) for my giraffe and it works
perfectly!!!
BB shell size should be 68mm and the axle on mine is 117mm!
http://tinyurl.com/2fl2s6
..............................
Regarding chain tension - I'm afraid the sprocket / chainring are
eccentric on your giraffe too...
read again here:
http://www.unicyclist.com/forums/showthread.php?t=18428
Hope this makes it clearer somehow,
Flaviu
--
UAC
"The World is a book, and those who do not travel read only a page"
(Saint Augustine)
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