probably dumb bottom bracket question

OK... '84 Trek 620. I blew it all apart and am now trying to organize
stuff to put it all back together. I find that the bottom bracket axle
is asymmetrical, I believe it is the one called "3S-B" here

http://www.sheldonbrown.com/harris/b...s.html#shimano

problem is, I don't know which way it goes - I assume "left end" is non
drive side? Looking at the cranks that doesn't make any sense though as
they appear to be symmetrical, or is that not a problem in practice?

nate

--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel

Nate Nagel wrote:
OK... '84 Trek 620. I blew it all apart and am now trying to organize
stuff to put it all back together. I find that the bottom bracket axle
is asymmetrical, I believe it is the one called "3S-B" here

http://www.sheldonbrown.com/harris/b...s.html#shimano

problem is, I don't know which way it goes - I assume "left end" is non
drive side? Looking at the cranks that doesn't make any sense though as
they appear to be symmetrical, or is that not a problem in practice?


Traditional crank spindles are longer on the right to allow
gear spacing. Notice how the outer face of your crank is
flat? Newer ones are curved for use with symmetric spindles.

When in doubt, or when test fitting a new size spindle,
assemble dry to check chainline. Since you're (I assume)
just cleaning and changing bearings with the original parts,
drop the long side in first, lube/assemble/adjust, mount
cranks and ride.

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971

AMuzi wrote:
Nate Nagel wrote:
OK... '84 Trek 620. I blew it all apart and am now trying to organize
stuff to put it all back together. I find that the bottom bracket
axle is asymmetrical, I believe it is the one called "3S-B" here

http://www.sheldonbrown.com/harris/b...s.html#shimano

problem is, I don't know which way it goes - I assume "left end" is
non drive side? Looking at the cranks that doesn't make any sense
though as they appear to be symmetrical, or is that not a problem in
practice?


Traditional crank spindles are longer on the right to allow gear
spacing. Notice how the outer face of your crank is flat? Newer ones are
curved for use with symmetric spindles.

When in doubt, or when test fitting a new size spindle, assemble dry to
check chainline. Since you're (I assume) just cleaning and changing
bearings with the original parts, drop the long side in first,
lube/assemble/adjust, mount cranks and ride.


yes, everything turned out to be in surprisingly good shape. The BB
cups are marginally questionable but felt good before disassembly,
headset is fine.

doesn't this mean though that your left pedal is slightly closer to the
center line of the bike than the right pedal is? The cups appear to be
about the same depth left and right. I've never measured down to that
fine level of detail before...

nate

--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel

On Sep 12, 2:58*pm, Nate Nagel wrote:
AMuzi wrote:
Nate Nagel wrote:
OK... '84 Trek 620. *I blew it all apart and am now trying to organize
stuff to put it all back together. *I find that the bottom bracket
axle is asymmetrical, I believe it is the one called "3S-B" here

http://www.sheldonbrown.com/harris/b...s.html#shimano

problem is, I don't know which way it goes - I assume "left end" is
non drive side? *Looking at the cranks that doesn't make any sense
though as *they appear to be symmetrical, or is that not a problem in
practice?

Traditional crank spindles are longer on the right to allow gear
spacing. Notice how the outer face of your crank is flat? Newer ones are
curved for use with symmetric spindles.

When in doubt, or when test fitting a new size spindle, assemble dry to
check chainline. Since you're (I assume) just cleaning and changing
bearings with the original parts, drop the long side in first,
lube/assemble/adjust, mount cranks and ride.

yes, everything turned out to be in surprisingly good shape. *The BB
cups are marginally questionable but felt good before disassembly,
headset is fine.


Roll a ball point pen over the cups to check for pitting. After you've
done this, which is pretty pointless--but makes you look studious--
repack with the thickest grease you've got going. Ride. Feel anything?
Grinding? No? Don't worry about. Oui? Then spend $25 at your LBS for a
UN-54, and be doine with it.