Soft cranks?

Dieter Britz said:

I put new cranks on a bike I was putting together. I am used to
tightening the bolts that press the cranks on the axle pretty tight, and
then they stay tight. But not these; they keep working themselves loose,
and I have to retighten them about once a day. I thought at first that
I had the washers the wrong way around, with the convex side out (I am
not even sure there is a concave, and a convex, side, but maybe there is)
but turning them around doesn't help either. What can be doing this?

Square taper BB? If so you might be running into the JIS square
taper spindle + ISO square taper crank problem (they have the same taper
but start it at a different width).

Cheers

joel

--
Human Powered Cycles | High quality servicing
[email hidden] | Low cost 2nd hand bikes
www.humanpowered.com.au | Bicycle re-use centre

Dieter Britz said:

I put new cranks on a bike I was putting together. I am used to
tightening the bolts that press the cranks on the axle pretty tight, and
then they stay tight. But not these; they keep working themselves loose,
and I have to retighten them about once a day. I thought at first that
I had the washers the wrong way around, with the convex side out (I am
not even sure there is a concave, and a convex, side, but maybe there is)
but turning them around doesn't help either. What can be doing this?

Not tight enough to staert with and after the first time they were
ridden lose, you trashed the inside flats..crank arm is dead.. 'May'
want to try a dry spindle and torque wrench...'may'
but maybe not...

Quoted message said:

--
Dieter Britz, http:<slashslash>w^3.chem.au.dk/~db

Dieter Britz said:

I put new cranks on a bike I was putting together. I am used to
tightening the bolts that press the cranks on the axle pretty tight,
and then they stay tight. But not these; they keep working
themselves loose, and I have to retighten them about once a day. I
thought at first that I had the washers the wrong way around, with
the convex side out (I am not even sure there is a concave, and a
convex, side, but maybe there is) but turning them around doesn't
help either. What can be doing this?

http://www.sheldonbrown.com/brandt/installing-cranks.html

Jobst Brandt

Dieter Britz said:

I put new cranks on a bike I was putting together. I am used to
tightening the bolts that press the cranks on the axle pretty tight, and
then they stay tight. But not these; they keep working themselves loose,
and I have to retighten them about once a day. I thought at first that
I had the washers the wrong way around, with the convex side out (I am
not even sure there is a concave, and a convex, side, but maybe there is)
but turning them around doesn't help either. What can be doing this?

I had a bad right crank that did this to me. It turns out that putting
on a new crank fixed it for me. I couldn't see the difference, but the
BB sure could.
Bill Baka