captainmarko
Member
Just curious.
Sent from my iPhone using Tapatalk
Sent from my iPhone using Tapatalk
Follow along with the video below to see how to install our site as a web app on your home screen.
Note: This feature may not be available in some browsers.
What an interesting question! (Yup, I'm a nerd.)
The short answer is "probably longer than that of the bike's owner."
Most bearings have two things that contribute to limiting their life, metal fatigue and contamination.
Bearing analysis indicates that bearings will always suffer surface fatigue failures eventually. Fortunately, they can be designed for the probability of when the failure will occur to be WAY out there. Think in terms of many hundreds of thousands of miles, if not more.
The vast majority of bearing failures are caused by contaminants getting past the bearing seals and into the bearings. Then the contaminant becomes a stress concentration problem as it passes between the rolling element and the bearing race. This causes local high local stresses which eventually lead to surface fatigue and eventual bearing failure.
How long do the seals last? That's a function of the environment the bike is exposed to (I bet I won't surprise anyone to say that more dirt and moisture is a higher risk for bearing contamination.) I don't have data to back this up, but I would assume that a GS ridden extensively off road would have a higher risk of a bearing failure than an RT ridden exclusively on the street.
In any event, bearing seal technology has matured a lot in the last 40+ years that I've been around this sort of stuff. Modern seals aren't bullet proof, but they're awfully darn good. For folks riding on the street (and again subject to revision based on service data from the field) I wouldn't worry about it. I'd focus on the more cosmic conundrums of crunchy vs. creamy peanut butter and great taste vs less filling beer.
Ride long and prosper,
Bob Stewart
Now that's the great thing about these owners' forums. One gets involved in a little discussion about a technical bit and ends up being rewarded with the answer to two cosmic conundrums!
Now THAT is an answer! Thanks, Bob.
And Trader Joe's Creamy Salted Almond Butter for conundrum #1. Anything brewed by Founders Brewing for #2, particularly the Backwoods Bastard.
I can't speak specifically about bmw motorcycle bearings, but ...
I had a 1996 bmw 328is that I raced the crap out of and one of the front wheel bearings gave up at around 100K miles. That was extreme conditions, riding over rumble strips to eek about a bit more surface, etc... If I drove the car sanely on the street, I'm sure it would have been many hundreds of thousands of miles. I sold the car to a guy with about 120K (60K of which were race track miles) and he finally blew the engine with about 160K miles on the odometer. That car was bullet proof in almost every way.
View attachment 74343
I was riding with bearings only on one side of the wheel...