Author Topic: Sealed bearings--How many miles?  (Read 7408 times)

0 Members and 1 Guest are viewing this topic.

Offline Westinghouse

Sealed bearings--How many miles?
« on: October 25, 2008, 12:38:45 pm »
I am considering another tour across the southern tier east to west. I am just beginning to purchase new components. Today I got a freewheel remover, and yesterday I bought a chain and a freewheel.

One thing I already have installed in the bottom bracket is a set of sealed bearings in a cartridge  that just screws into the bracket. It is not a top end cartridge; it cost about $30.00--$35.00. It already has something over 1500 miles on it. Does anyone have any idea about how many miles it is good for in loaded, long distance touring?

Offline whittierider

Sealed bearings--How many miles?
« Reply #1 on: October 25, 2008, 02:47:10 pm »
The Isis type (and probably Octalink too, since it's the same idea) don't last long at all.  Our son who only weighs 130 pounds or so and doesn't abuse equipment seems to get about 3,000 miles out of one.  That's not loaded touring either, but he does ride hard and climbs about 4,000 feet per hour.  The problem with them is that when they went to the bigger spindle, it didn't leave room inside the BB shell for big-enough ball bearings, and it also put the two sides' bearings too close together so there's a huge load on them from the side-to-side pedaling forces.

The answer to that was the external-bearing BBs, which put the two sides' bearings a lot farther apart and of course also leave a lot more room for adequately sized ball bearings.  We have these in a couple of our bikes, one with 7,000 miles and one with nearly 16,000 miles, and they both still feel brand new.

The external-bearing type requires a crankset that has the spindle as an integral part of the right crank arm.  Mine requires only an 8mm allen wrench to remove the crankset from the bike and re-install it, and it's so easy that it's almost worth doing it every time I want to clean that part of the bike.

People sometimes think that the external-bearing BBs would give you a wider Q; ie, put the pedals farther apart.  This is not the case though.  On the left side, the crank arm goes right up against the bearing, not leaving any of the spindle showing.  On the right side, the bearing is even outboard of the tiny chainring, and is almost in the plane of my middle chainring.

This message was edited by whittierider on 10-25-08 @ 12:02 PM

Offline Westinghouse

Sealed bearings--How many miles?
« Reply #2 on: October 25, 2008, 04:26:48 pm »
Thanks for the information. It looks like I had better just install a spindle with cups and bearings.

Offline DaveB

Sealed bearings--How many miles?
« Reply #3 on: October 31, 2008, 09:39:37 am »
ISIS bottom brackets were highly variable in quality.  Some wore out very quickly and others were fairly durable.  

Octalink (Shimano) bottom brackets are similar in concept but generally much more reliable.  I have two that are 15,000+ miles old and still in excellent condition with no play and no noise.

Shimano's older square taper cartridge bottom brackets were very durable also.

Offline bogiesan

Sealed bearings--How many miles?
« Reply #4 on: November 02, 2008, 07:47:07 pm »
I have a Shimano sealed bottom bracket rig with more than 27,000 miles
on it on my Tour Easy recumbent. To get 3k out of a top-of-the-line
bearing implies much.

david boise ID

go, ristretto, FCP/AE
"Read the manual."
I play go. I use Macintosh. Of course I ride a recumbent