Dear MOby,

I have a very short question for Ask MO Anything. Why do motorcycle
factories insist on using ball bearings for OEM steering-head fitment, when every mechanic I know will replace them with aftermarket tapered roller bearings once they wear out? Why not just use tapered rollers to begin with?

Regards,
Kelvin Lau


Dear Mr. L,

I remember when the first R1 came out in 1998, Yamaha told us it chose to use roller bearings because they provided better steering feel and feedback. Intuitively it’s hard to argue with that since there is less contact area between a ball bearing’s inner and outer races, and that was backed up by the fact that the R1 was the sweetest-handling literbike ever at the time.

But we may have just been had: Our friend Brian Gillen, MV Agusta’s head engineer, tells us using ball bearings in the steering head does offer advantages regarding packaging, since they take up less space and also weigh less. But in most cases, he says, the choice is primarily cost; tapered roller bearings can cost over twice as much as ball bearings.

The big advantage to tapered rollers is that they last much longer, thanks simply to the fact that the load is spread over much greater surface area – among other things which require more knowledge than Ask MO can bring to bear. All I know is, 20,000 miles or so later, the ball-bearing ones in my 2000 R1 are shot.

Compare this tapered roller bearing to the ball bearing in the lead image.

Compare this tapered roller bearing to the ball bearing in the lead image.

012317-ask-mo-ball-bearings-angle-diagramSKF says: “Tapered roller bearings have tapered inner and outer ring raceways and tapered rollers. They are designed to accommodate combined loads, i.e. simultaneously acting radial and axial loads. The projection lines of the raceways meet at a common point on the bearing axis to provide true rolling and low friction. The axial load carrying capacity of tapered roller bearings increases with increasing contact angle α.”

And after that it gets complicated, okay?

Keeping your bike’s steering head bearings properly lubed and adjusted will go a long way toward maximizing their lifespan, especially if it has ball bearings, but it’s a thing plenty of people ignore. If you can waggle the front wheel around when somebody raises it off the ground for you with the kickstand (or if you have a front-end stand even better), even if just a millimeter or two, you’ve really probably already waited too long. Chris Redpath of MotoGP Werks tells us if a bike with its original bearings has reached that stage, he’ll usually just replace the ball bearings with tapered rollers.

If you try to replace them yourself, be sure and follow instructions and/or the manual when it’s time to tighten things up, because if your bike is anything like my old R1, the tightening procedure isn’t what you’d (I’d) expect: The two locking ring nuts, under the upper triple clamp that look like what you should really tighten, are supposed to be torqued to just 20 ft-lb and 6.5 lb-ft (lower and upper).

It’s the steering stem nut, on top of the upper clamp (the one idiots scratch all up by carrying 15 keys on their keychain) that needs to be torqued to a bicep-rippling 85 lb-ft on my bike.

Yo, where’s my 36mm socket?

Yo, where’s my 36mm socket?

PS: No bike manufacturer makes its own bearings; they nearly all come from outside suppliers. If you have time to take your bike apart and get the old ones out, and if you’re lucky enough to have a bearing supply store in the neighborhood (they’re all over) with a nice person behind the counter armed with a micrometer, you can save substantial cash by going straight to the source.


Direct your motorcycle-related questions to AskMoAnything@motorcycle.com, though some say we’re better at non-motorcycle-related ones…

  • D H

    So Much hates for the ball bearings…I have another story on them. 2002 Honda CBR954RR came from factory originally with tapered bearing for the steering stem. After some complaints and lots of accident for tank slapper (due to excessive wheelie for instance), Honda motor gave up and began a recall process to swap the tapered to the ball bearing on the bikes. Any CB954RR that’s went to the recall process got the steering stem notched to show the work was completed. The 2003 production all have the ball bearing instead of the tapered and no complaint ever heard again. The accidents still happened but people seemed happier with the ball bearing, why? It’s give more resistant (less efficient) than tapered thus makes the steering less twitchy. By the way I have a set of Factory OEM steering stem bearings for CBR954, anybody want to buy it?

    • D H

      By the way, I used to own 2000 R1 for more than a decade. Bought it brand new and it was the faster Blue color. I cried myself to sleep after I sold it and I am still missing the good chore of doing the carb synchros every month….Not!

  • JMDGT

    Timken tapered roller bearings. The best on the planet

  • halfkidding

    I’ve had 2 Kawi ZZR 1200’s, both bought very slightly used. (great deals) Anyhow they both have suffered from a very specific problem. That being a front end wobble on decel centered at 45mph, and only there, and it can be a tank slapper with hands off the bars. Not at 20 or 140. By meticulous adjustment of the steering stem and careful sequential tightening of the entire front end from axle to fork pinch bolts I banished it from the first but never got it out of the second. I have the tapered rollers on the shelf and will install before I sell it this spring. I can live with it but don’t want some noob to freak out.

    • Scott Silvers

      Why are you decelerating with your hands removed from the handlebars………? Most bikes do this and it’s very much tire related, or loose steering head..

      • Jon Jones

        Agreed.

  • Craig Hoffman

    Any manufacturer that cheaps out and uses ball bearings in the steering head to save a few bucks deserves to be flogged and mocked on the Internet. We are talking about a component that affects the steering of a motorcycle here, which is a pretty critical deal.

    • Andre Capitao Melo

      Meh, with proper maintenance they last a long time, and give signals of failure waaay before it becomes critical.

  • Gruf Rude

    Adjustment on the tapered bearings is critical and an often-forgotten component of the adjustment is the need to loosen the triple clamps on the fork tubes. The tubes must be free to move within the triple clamps as the upper and lower clamps squeeze together on the bearings. Otherwise, the top and bottom clamps flex slightly as the bearing is adjusted and then strain to move back where they were, which generally causes the adjustment to go bad quickly. Only the bottom clamps need to be loosened to allow the adjustment and, of course, the clamps must be re-tightened after the bearing adjustment is completed.

  • gunny 2shoes

    meh, the first picture is a bearing assembly for a shaft. individual balls on factory races properly lubed and adjusted are completely satisfactory.

  • mikeinkamloops

    Short version — ball bearings are cheaper.

  • Pierre Drouin

    Just for info. Honda on their multi-millions MotoGP bikes use ball bearings… IIRC it was pictured on Superbike Planet a few years ago.

    • TonyCarlos

      Well that seems to be in keeping with what the article says. Balls provide better feel but are less durable and require more frequent service.

  • Doug T

    My 02 Tiger had tapered bearings, had them changed out @ 40,000 miles and was told that yes they were worn out, but with new bearings I really don’t feel any change, it still has a slight front end wobble on deceleration at 25 to 45 mph, at other speeds it’s just fine.

  • The Kawasaki Vulcan 1700’s have problems with wobble, particularly on the Voyager and the reason, it seems, is the ball bearings. Change out to tapered roller bearings and problem solved. Another observation is that the ball bearings look to be hardly lubed and with what looks like Vaseline. A very light grease and not much of it. This happens with bikes with under 10K miles too.