I have an entry range gravel bike (Kona Rove AL 2017) with disk brakes and the cup and cone front wheel hub shown in the pictures. There is the cone itself that threads on the axle and a top ring that presses against the ball bearings to prevent them from coming loose (see 1st and 2nd pictures for the disassembled bearing). The inner part of this ring is made of rubber to rub against the cone and seal the bearing. Not shown are the lock nuts and washers.

pic 1: bearing disassembled

pic 2: cone and sealing ring made of metal and rubber

The problem is that braking exerts a rather big lateral force on the wheel that slowly forces the ring to the outside, which in turn causes the bearings to have a lot of lateral play.

How do I deal with this? I thought of changing this setup to one where the cone actually overlaps and presses the ring into place, preventing it from coming loose. Alternatively I could buy a tool to hammer cartridge bearings into hubs and periodically "tighten" the rings. This would be a pain since I think their inner diameter would not fit the cone nut, forcing me to disassemble the bearings each time.

Edit regarding the misunderstandings on the comments and answers so far.

Let me explain better how my bearings are composed:

There is the cup part where the balls sit, seen in the first picture. To close the bearing on the outside there are the cone and sealing ring seen in the second picture. It is the sealing ring (and not the cone itself) that is causing my problems, as I will detail. This ring is metallic on the outside and made from rubber on the inside (to rub against the cone).

The ring fits very tightly into the hub hole (as tight as a normal cartridge bearing fits). This ring moves tight with the hub and rubs gently against the cone to prevent dirt from coming in. The ring is held in place only due to how tight tight it fits the hub - there is nothing preventing it from moving to the outside if a lateral force is applied from the inside. The cone itself does not overlap this ring (see 3rd picture).

pic 3: bearing assembled (without lock nut)

Due to the disk brakes on this bike a lot of lateral force is exerted during breaking. In this bearing setup, as I noticed recently and tried to explain above, if the lateral force applied is strong enough it overcomes the pressure of the tight fit and the ring is slowly moved out (the cone remains always in place, since it is screwed).

Now if this ring does not sit tight to the cup and balls they have play and so does the axle in relation to wheel.

How do I know this is the root cause of the problem? I bought the bike new about a year ago and its front wheel slowly built up lateral play under braking (which in turn induces fork vibration - but that is another story). This lateral play reached about 2 cm at the tire before I decided to inspect the hub last week and noticed the rings were not tight to the balls. After I pressed them again against the balls the play disappeared.

I should also mention that I had the bike inspected twice by the mechanic in this year, explicitly complained about deteriorating fork vibration and wheel play (since then I did not knew the root cause of it) and was told it was normal and still safe to ride.

  • 2
    Are these all your parts? It looks like you a missing a part, the lock but that is tightened against the back of the cone. The part in the second picture is only a seal, it doesn’t hold the bearings, that is he job of the cone nut.
    – Rider_X
    Commented May 20, 2018 at 21:40
  • I have the lock nuts, and they were correctly tightened. It is not the cone who becomes loose, rather the ring shown in the picture, because the cone is not wide enough to overlap it and hold it place. The bearing top is composed of the ring and the cone. The problem lies in the ring.
    – calofr
    Commented May 20, 2018 at 22:51
  • I could edit the title to make the question clearer, but I don't know how that ring-like part of the bearing is called. here they call "cone" to all the outside part of the bearing...
    – calofr
    Commented May 20, 2018 at 22:55
  • It's called dust cap, and it's not holding anything in place. Braking should not affect it in any way.
    – ojs
    Commented May 21, 2018 at 2:37
  • 2
    Comment on your updated question. I think what everyone is trying to say here is that the sealing dust cap should not have any function holding the balls in place. You should be able to assemble and adjust the the bearing without the dust cap, and the balls would all stay in place. (Obviously you would not ride the bike in this condition.) Commented May 21, 2018 at 17:02

1 Answer 1


This isn't making sense.

The cone holds the balls in place.

The locknuts (not shown) keep the cones in place.

The grease seal has no effect on the tightness of the bearing.

If your cone is moving, you have not tightened the locknut against the cone (or it has been omitted).

You need a cone spanner (thin spanner) and a second spanner, to tighten the locknut hard against the cone.

It is a bit tricky to tighten cones - or more accurately, you will find yourself having to redo it a few times to get it correct. Correct is when there is a tiny amount of play, that disappears when the quick-release is tightened. Check for play after a few days, and readjust if needed.

  • It is not the cone who is moving, rather the ring shown in the picture. The problem is that the cone does not overlap the ring is order to hold it into place, so it slips with the lateral force
    – calofr
    Commented May 20, 2018 at 22:47
  • 1
    Still not making sense. The grease seal should be sitting half way down the cone. The outer edge of it is a snug/tight fit into the hub, so it doesn't rotate. Nothing the grease seal does should cause the cone to have play
    – Henry Crun
    Commented May 21, 2018 at 0:39
  • 1
    Do you have the right size bearings. Usually they are 10 x 3/16" balls in the front, 9x1/4" at the rear. Your picture looks pretty full of balls. Have you put 1/4" in place of 3/16" balls?
    – Henry Crun
    Commented May 21, 2018 at 0:41
  • @goncalofr Checking assumptions - is there a lockring on each side ? No dust cap is load-bearing.
    – Criggie
    Commented May 21, 2018 at 5:06
  • I measure some front cones at 15mm OD, they take 3/16" balls. Rear cones 16.5mm OD, they take 1/4" balls. I have a bike with the bigger cones and balls in the front hub, but the cone diameter is a giveaway.
    – Henry Crun
    Commented May 21, 2018 at 5:43

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