We get through a lot of wheel bearings at AdventureRide. It’s hardly surprising when you look at the operating conditions – some of the bikes cover 300 to 400 miles a week during which they’ll do maybe nine river crossings and be immersed countless times in muddy water before being subjected to a 2500psi pressure wash three or four times. It’s not a healthy environment for a bearing and each bike will consume numerous sets of bearings during a season.
“Not a healthy environment for a bearing…”
Last year I stopped buying expensive bearings and started fitting what the trade term ‘budget’ bearings. They lasted as well as the more expensive bearings but had a tendency to break up when being removed from the hub causing another hour of work to remove the outer race, usually at a time when I could least afford it. I’m now back on branded bearings. Recently I bought a spare rear wheel off eBay and when it arrived I noticed some clever soul had fitted a grease nipple to it. Hallelujah! I have seen the light… a proper old school, simple solution to an age old problem.
I’ve since started fitting grease nipples to all the bikes and it occurred to me there will be readers out there who have never even seen a grease nipple, let alone understand their significance or know how to go about fitting them.
The idea of filling a hub with grease is not simply to lubricate the bearing, the grease is there to act as a barrier to prevent the ingress of dirt and water. Packing a hub with grease and it will prolong the life of the bearing but fitting a nipple as well will prolong it much more. With a nipple fitted it’s possible to periodically introduce more grease which will have a purging action, forcing grease through the bearing and pushing out the old grease which has been contaminated with water and grit from the outside world. It’s such a simple idea and one which for some reason has fallen out of vogue with manufacturers.
Here’s a simple pictorial guide how to go about fitting a grease nipple to your hub. Usual caveats apply, ie , don’t blame me if you snap a drill off in your hub and I’m also assuming the reader has a basic grasp of workshop techniques. If you haven’t then please get a competent mechanic to do the work.
1] You’ll need a decent drift to remove the bearings, I use a piece of 9mm stainless bar which has a nice defined lip. First, put the bar into the axle tunnel and give it a sharp sideways knock to dislodge the bearing spacer a couple of mm. You can then insert the drift from the other side and gain a purchase on the inside edge of the bearing to drift it out.
2] Always get plenty of heat into the hub before trying to drift out the bearing. The bearing should pop out quite easily after warming the hub . A good tip is to decide which is the least knackered bearing [usually the one opposite the sprocket side] knock it out first and then, when you’ve removed the spacer from within the hub, you can get a really good purchase with the drift on the back of the remaining bearing . This lessens the chance of punching just the inner race out of the weaker bearing leaving you with the trauma of having the outer race stuck tight in the hub. If this happens get a Dremel with a grinding stone on it and tickle away at the outer race taking care not to break through the steel and damage the bearing housing. You’ll find the race will probably drop out due to the intense heat long before you get close to the ally hub.
3] Decide where you want to place the grease nipple [equidistant between the two bearings is best] and centre punch the spot using a punch and nice light hammer. Weigh up the orientation of the spot against the spoke pattern, make sure you can get the drill in.
4] Unless you want to unlace the spokes and dismantle the wheel… and I’m guessing you don’t …you’ll need one of these nifty 90 degree adapters for your drill so you can get in between the spokes and drill a hole in the hub . Drill a 2mm pilot hole and then follow on with a 5mm drill.
5] Using a ratchet tap wrench carefully tap a 6mm thread into the hole. It looks tricky but is actually very easy to do. Ideally you want a wrench with a removable tommy bar and a knurled top ring so you can start the thread off nice and square to the hub by hand before resorting to the tommy bar
6] Nicely done, don’t forget to thoroughly flush out the hub removing any swarf and make sure the hub void is spotlessly clean.
7] Install the nipple using a bit of Loctite thread lock. I’ve used a 45 degree nipple here but straight ones will work just as well.
8] Before refitting the bearing be sure to remove the inner seal on both bearings, if you don’t do this there’s not much point installing a nipple! Don’t forget to replace the bearing spacer in the hub. Sometimes these spacers come with foam rubber collars which help centralise the spacer relative to the bearing inner race. You’ll have to ditch these collars because they will act as a barrier to the grease. It’s no hardship, you just need to take a bit of extra care when installing the second bearing and make sure the spacer is lined up properly before seating the bearing. You’ll work it out…
9] This is the kit I used, hammer , drift, centre punch, 2mm pilot, 5mm drill, 6mm tap set, tap wrench, blow torch, drill, 90 degree drill adaptor , nipple and a couple of bearings. I bought everything off eBay, the taps drills and nipples were a few pounds, the only expensive thing being the 90 degree drill adaptor at thirteen quid.