Outboard bearing bottoms bracket (hollowtech II) - assessment of wear and lateral play, lifespans & when to replace?

Question

I have a road-version hollowtech II bottom bracket (shimano 105 model - BB-R60). over the last couple of days i noticed a very slight clicking feeling as i pedalled.

removing the crankset i find that the left-hand side of the BB cup feels smooth and snug with no play. however the right sided cup has a very small amount of lateral play.

i last replaced the bottom bracket less than six months ago (at which point the old one had developed a significant amount of play after around 1000miles) and i would estimate that the new one has only done around 400miles since. These bottom brackets are non-serviceable, sealed units.

Googling suggests that it's not uncommon to get through these pretty quickly, although this does seem odd to me as i thought that outboard bearings were supposed to be more durable and I have hardly ever had to service, never mind replace, the older BBs on my older bikes.

i'm about to leave in tour again (around 3000 miles) and I'm wondering how to interpret this small amount of lateral play

• will it definitely get worse, and if so how quickly?

• should i just replace it now, or should i take another one with me and replace it when it has developed more play?

i'm also worried that this relatively new bottom bracket is already showing signs of wear.

• is this indicative of me doing something wrong during installation and/or usage?

it's worth noting that although the first bottom bracket came with the bike, i did replace the crankset a few hundred miles before before it started to show play so feasibly i could have done something wrong then; i could have possibly overtightened the plastic pre-load screw on the crank. the second BB didn't have an ideal installation as i did it at the side of the road on tour and there was a tiny tiny amount of drizzle, but i don't think i overtightened the pre load and if any water got into the shell it was only a minute amount.

as it's a touring bike it has also had a fair amount of use in the rain and with heavy rear panniers and the occasional rough road.

• is this a normal lifespan for these BBs? i.e do i need to be thinking replacing the current BB and taking another one or two spares with me for a 3000 mile trip? so far my BBs are looking like their average lifespan is going to be around 1000 miles and i'm planning on cycling 3000 over 3 months...

Answer 1

That there's some amount of play you can feel through the black plastic shield in one of the bearings with the cranks out isn't necessarily a big deal. What you're looking for is the quality of the adjustment you can get out of it with the cranks on. If you're forced to either have it grindy/frictiony or have play or both at the same time, that's a BB that needs replaced.

Broadly speaking, yes you seem to be wearing them out on the fast side. Your description of the issues you're having somewhat suggests not enough care given to keeping the bearing adjusted. You shouldn't have to mess with it all the time, but every once in a while on a Shimano outboard BB to be sure. You're trying to always keep it slightly preloaded. Another way of saying it is as loose as possible but with no play. Too little or too much preload will trash the bearings.

Chronically running through these BBs, especially despite ones best efforts with adjustment, can also suggest a shell that needs facing and chasing to get better bearing alignment.

Outboard BBs, the cheaper ones in particular, really aren't all that durable compared to high quality square taper cartridge BBs. I have a BB-UN72, Shimano's nice but modestly priced upper end square taper unit, with thousands of miles on it in all weather conditions and over 10 years old that's still utterly perfect. No outboard BBs do that that I'm aware of.

If you're doing high mileage touring then just getting a King or Phil along with making sure the shell is well-prepped would probably make some sense. What kind of mileage you get still depends on you and the conditions you ride in, but they are more robust. I'm also a big fan of the Enduro replacement bearing kits for Shimano outboard BBs, because they replace the bearing with a larger and more durable cartridge by getting rid of the black top hat seal and putting a different kind of seal in its place, but the catch with them is you more or less need a special tool to install them into the cups. I've observed them be a good solution for folks having trouble with tearing through BBs though.

Answer 2

I've just replaced Shimano RS500 outboard bearings on a bike with Rohloff internal gear hub and Gates belt drive, which I use for light touring and commuting. The bike had done 4000 - 5000 miles from new, which is less than 30% of the mileage that I would have got from a cheap Stronglight sealed cartridge with square taper on my previous bike.

The failed RS500 went from satisfactory to a gross amount of play very quickly.

When I took the Hollowtech crankset out of the bearings, the outer face of the plastic casing that you see on the end of the bearing came away as a disc on the axle of the crankset. The thin cylinder of plastic that holds the axle in the inner case of the actual bearing had separated from the outer flange and had drifted centrally off the bearing.

This was probably why the play increased so suddenly, but there was a lot of dirt inside the units and on the axle; the drive side bearing had obvious play in it.

I wonder if your outboard bearings failed in the same way, Rich. Unlike Nathan, I don't think that there's much scope for prolonging their life by adjusting the pre-load. There was still no end-to-end float when mine had failed completely.

I'm amazed that you carry tools to change a bottom bracket on tour. I don't think that a decent one should ever fail in a way that wouldn't give you a few hundred miles to get to a bike shop. I've just ordered a Phil Wood bearing to give me peace of mind on tour. It should easily pay for itself when you factor in your own/bike shop's labour costs and disruption to use of bike.