I need help tightening my unicycle's cotterless crank
Pepsco
and after a week of riding it my left crank started to become more
loose and more...adjustable but in a bad way. Here's a pick of the
loosened joint thing http://i304.photobucket.com/albums/nn171/Fantansygirl64/unicycle.jpg
If you have any instructions or links to videos on how I can fix him
please post it on here! I really want to save my darling unicycle.
John Doe
Just in case you do not get complete satisfaction here, there is a
unicycle group that still has a few readers.
rec.sport.unicycling
By the way... Not that it matters, but can you take a larger
resolution picture?
Good luck and have fun.
Tºm Shermªn™ °_°
Good and bad news: <http://sheldonbrown.com/brandt/installing-cranks.html>.
--
Tºm Shermªn - 42.435731,-83.985007
I am a vehicular cyclist.
thirty-six
> My unicycle (from Avenir) has a 20' inch wheel with cotterless cranks
> and after a week of riding it my left crank started to become more
> loose and more...adjustable but in a bad way. Here's a pick of the
> If you have any instructions or links to videos on how I can fix him
> please post it on here! I really want to save my darling unicycle.
Normally on a bicycle using a bottom bracket axle to anchor the
cranks, the flats of a square taper are hidden or very nearly so. I
don't know how unicycle axles are normally formed but it does take the
use of a standard 3/8" bar from a socket set to get the required
amount of torque. I forget what it is but can sense it on a clean
oiled undistorted taper. This probably wont exacly apply in your case
and a little remedial work may be necessary with a scraper. First of
all we need to find out whether it is a bolted or nutted axle and if
it is a bolted, whether it is hex head or hex socket. A photo from
the side of the cycle will show what type of dustcap is fitted to the
crank and we can go from there.
AMuzi
I can't see anything useful in that snapshot.
Remove both cranks, lubricate tapers and threads, torque to
55Nm. If the crank has been damaged form being ridden loose,
it will wiggle off again and you will need a new one.
--
Andrew Muzi
<www.yellowjersey.org/>
Open every day since 1 April, 1971
dusto...@mac.com
(IMHO and I'm not one of the shop-owner experts who post here, but...)
If that was a new unicycle, this is apparently a warranty issue, a
failure due to improper installation-- that crank arm was not put on
tight enough, from what you've said so far. Period, end of
"discussion".
If not an "in warranty" issue, and you have to deal with this on your
own dime:
Clean everything involved, really clean. Grease (white lithium, or
other real lube, not Vaseline or WD40) everything-- threads, washers
(both sides), under bolt heads, and especially, the bottom bracket
tapered flats, and put a coat on the inside of the crank tapers, too.
It doesn't take tons of lube, it takes careful application.
If the BB flats are rough, do like Trevor implied-- without removing
steel from the spindle, provide some careful scraper work to get the
flats smooth and foreign material off.
Helpful reading:
<http://www.parktool.com/blog/repair-help/torque-specifications-and-
concepts>
300+ in-pounds of torque is *tight*. Note the long handle on the
torque wrench. Again, your crank arm was installed properly-- "not
tight enough".
<http://www.parktool.com/blog/repair-help/crank-installation-and-
removal-square-spindle-type>
Park chickens out on the "lube the BB flats" issue. You can look this
mess up in the Jobst stuff that is archived at Sheldon Brown, near the
"your crank is ruined" stuff, where he talks about people improperly
tightening and re-tightening crank arm fastening bolts, which can
cause crank arms to crack out, from testimony. Lube on BB tapers has
nothing to do with splitting crank arms; Park just doesn't want to
deal with "liability issues" (incl. complaints) from mistakes made by
readers of their advice site.
Jobst is right on some things, wrong on others, as I've been using a
"ruined" (most emphatically NOT in any way "ruined") crank arm for at
least ten years on my main ride, a crank arm (left, like Jobst says!)
that might have loosened more than once (ahem) and has been on/off BB
spindles several times for BB service and swapping between bikes, all
after it was run loose.
"Put it back on" with proper care and tightness. Cleanliness, thorough
lubrication, and sufficient, measured torque per manufacturer
recommendations give you your best shot at a good installation.
"See what you get", if you can't go the warranty route. I'd predict a
good outcome, from my experience. Whatever: always worth a shot, IMHO.
If the crank arm is indeed ruined, you'll know early on, from the
experiences of others I've seen related here. Mine, and at least one
other I can call to mind, have gone back on and stayed on (repeatedly)
despite admitted grievous misuse.
--D-y
dusto...@mac.com
A. Muzi has a lot more practice & can do this lots faster than I can--
witness, he got his answer in while I was dithering with mine.
For reference and possible ease of use with the odd torque wrench you
might find floating around: 55Nm is equal to (phew!) 486.791018538 in-
lbs according to an online calculator-- just to emphasize "tight" <g>.
--D-y
thirty-six
Campagnolo are specific in saying no to grease on the threads. I
guess this can result in loosening and have always followed (after a
brief period without any engineering education) normal engineering
practice of oiling the bolt threads, and the same lubricant is also
ideal for the taper.