Shimano UN52 through UN73 BB's

Well I finally managed to wear out the balls and spindle in my cup and
cone bottom bracket after xx000 miles. Actually if I had bothered to
read some of the maintenance posts and replaced the balls two years
ago it might have lasted longer. Been looking at the Shimano UN52
through UN73 cartridge product line for a replacement. Are the UN73
models sealed better than the less expensive models or just lighter in
weight? I doubt I would notice the difference unless the bearings are
of lower precision or not as durable. What has been other peoples
experience?

wrote in message
news
Well I finally managed to wear out the balls and spindle in my cup and
cone bottom bracket after xx000 miles. Actually if I had bothered to
read some of the maintenance posts and replaced the balls two years
ago it might have lasted longer. Been looking at the Shimano UN52
through UN73 cartridge product line for a replacement. Are the UN73
models sealed better than the less expensive models or just lighter in
weight? I doubt I would notice the difference unless the bearings are
of lower precision or not as durable. What has been other peoples
experience?

UN-7X have a hollow axle, so they're lighter. Not sure about the bearings,
but I certainly can't tell a difference in a few thousand miles. One nice
advantage of the hollow axle is that you can use a skewer to hold the BB
removal tool in place while you crank on the wrench. Not that big of a deal
I guess.

Kyle

wrote:

Well I finally managed to wear out the balls and spindle in my cup and
cone bottom bracket after xx000 miles. Actually if I had bothered to
read some of the maintenance posts and replaced the balls two years
ago it might have lasted longer. Been looking at the Shimano UN52
through UN73 cartridge product line for a replacement. Are the UN73
models sealed better than the less expensive models or just lighter in
weight? I doubt I would notice the difference unless the bearings are
of lower precision or not as durable. What has been other peoples
experience?

I destroyed a UN52 in 70 miles. I replaced it with a UN72 which is
beginning to feel a bit rough after 3000. I don't think they last as
long as cup and cone in Californian conditions, but all the cup and cone
BBs I've used have died because of water penetration.

Having said all that, I do seem to be exceptionally hard on BBs. I know
I have a lopsided pedalling style because my right gastrocnemius muscle
is about 1.5 times thicker than the left one, and this can't help much.

On Sun, 19 Sep 2004 08:44:57 +0100, Zog The Undeniable
wrote:

wrote:

Well I finally managed to wear out the balls and spindle in my cup and
cone bottom bracket after xx000 miles. Actually if I had bothered to
read some of the maintenance posts and replaced the balls two years
ago it might have lasted longer. Been looking at the Shimano UN52
through UN73 cartridge product line for a replacement. Are the UN73
models sealed better than the less expensive models or just lighter in
weight? I doubt I would notice the difference unless the bearings are
of lower precision or not as durable. What has been other peoples
experience?

I destroyed a UN52 in 70 miles. I replaced it with a UN72 which is
beginning to feel a bit rough after 3000. I don't think they last as
long as cup and cone in Californian conditions, but all the cup and cone
BBs I've used have died because of water penetration.

Having said all that, I do seem to be exceptionally hard on BBs. I know
I have a lopsided pedalling style because my right gastrocnemius muscle
is about 1.5 times thicker than the left one, and this can't help much.

Sounds like the UN52 that only went 70 miles had a manufacturing
defect that caused a catastrophic failure?

I don't like the idea of going from 1/4 inch balls in the cup and cone
setup down to 3/16 in the cartridge. I would have bought another C&C
setup but my LBS recommended a cartridge replacement. Here in Florida
we get caught in the rain quite often so seal longevity does need to
be considered.

On Sun, 19 Sep 2004 02:16:36 GMT, "Kyle.B.H" wrote:


wrote in message
news
Well I finally managed to wear out the balls and spindle in my cup and
cone bottom bracket after xx000 miles. Actually if I had bothered to
read some of the maintenance posts and replaced the balls two years
ago it might have lasted longer. Been looking at the Shimano UN52
through UN73 cartridge product line for a replacement. Are the UN73
models sealed better than the less expensive models or just lighter in
weight? I doubt I would notice the difference unless the bearings are
of lower precision or not as durable. What has been other peoples
experience?

UN-7X have a hollow axle, so they're lighter. Not sure about the bearings,
but I certainly can't tell a difference in a few thousand miles. One nice
advantage of the hollow axle is that you can use a skewer to hold the BB
removal tool in place while you crank on the wrench. Not that big of a deal
I guess.

Kyle


I am not completely sold on the cartridges with the smaller ball
bearing sizes lasting as long as a C&C regardless of the price. Maybe
a generic inexpensive aluminum cup replacement would be the way to go
if I'm only going to get 3000 miles out of it anyways?

wrote:

Sounds like the UN52 that only went 70 miles had a manufacturing
defect that caused a catastrophic failure?

That's possible, even probable, but I wouldn't take the risk again. The
failure mode was squeaking and gradual seizing. When I got the bike
home the cranks were really quite difficult to turn by hand.

dsr- Are the UN73
models sealed better than the less expensive models or just lighter in
weight? BRBR

Hollow axle vs solid, otherwise pretty identical.

BTW-Phil Wood makes some really nice compatible BBs that will last a LONG time
and are rebuildable.

Peter Chisholm
Vecchio's Bicicletteria
1833 Pearl St.
Boulder, CO, 80302
(303)440-3535
http://www.vecchios.com
"Ruote convenzionali costruite eccezionalmente bene"

wrote in message
...

I am not completely sold on the cartridges with the smaller ball
bearing sizes lasting as long as a C&C regardless of the price. Maybe
a generic inexpensive aluminum cup replacement would be the way to go
if I'm only going to get 3000 miles out of it anyways?

I weigh 235, ride in the rain/slush/snow frequently, and get many more
miles than that out of UH52's. The last one I replaced had perhaps 15K
miles on it and had just developed a little bit of axial play. Since they
only cost $20 or so, it's not a big deal to replace them every few years,
I'd be overhauling C&C BB's more frequently than that anyway.

On Sun, 19 Sep 2004 13:19:33 GMT, "Peter Cole"
wrote:

wrote in message
.. .

I am not completely sold on the cartridges with the smaller ball
bearing sizes lasting as long as a C&C regardless of the price. Maybe
a generic inexpensive aluminum cup replacement would be the way to go
if I'm only going to get 3000 miles out of it anyways?

I weigh 235, ride in the rain/slush/snow frequently, and get many more
miles than that out of UH52's. The last one I replaced had perhaps 15K
miles on it and had just developed a little bit of axial play. Since they
only cost $20 or so, it's not a big deal to replace them every few years,
I'd be overhauling C&C BB's more frequently than that anyway.

15K is about the number of miles I got with each of my last two C&C
BB's. After about 7500 miles the cones started needing adjustments.
Given the unbalanced alternating nature of pedaling, bearing races
must wear unevenly. My thinking is that once a bottom bracket wears
enough to make noise it probably should be canned anyways.

Cartridges with plastic cups look a little flimsy and would require a
special tool to install. I'm wondering if I could get away with using
a dull chisel to tap metal cups around with as long as I have clean
shell threads?

On 19 Sep 2004 13:06:36 GMT, (Qui si parla
Campagnolo ) wrote:

dsr- Are the UN73
models sealed better than the less expensive models or just lighter in
weight? BRBR

Hollow axle vs solid, otherwise pretty identical.

BTW-Phil Wood makes some really nice compatible BBs that will last a LONG time
and are rebuildable.

Peter Chisholm
Vecchio's Bicicletteria
1833 Pearl St.
Boulder, CO, 80302
(303)440-3535
http://www.vecchios.com
"Ruote convenzionali costruite eccezionalmente bene"

The bottom brackets that look like the best design are the Ritchey
super logics. Even though these are not cartridge units they look
very well sealed. If you can press the bearings out of the cups and
get replacement sealed units, a super logic BB could last the life of
your bike. Square taper cranks are kind of old technology so there is
some good value in NOS BB's if you can find them.