advertisement


Any knowledgeable cycle mechanics?

wcavanagh

pfm Member
I'm swapping a groupset over onto another frame and something doesn't seem correct. Hoping someone has experience here.

The bottom bracket is Shimano 4600 hollogram II style external cups. There's a free moving bearing in the cup on the right, but (maybe) not on the left because it doesn't move at all. Now, silly as it may sound, I can't even tell if the left side is a seized bearing or whether it's simply a structural support.

Should both cups have a free moving bearing, or just the one on the drive side? I would think both but I might be wrong.
 
I've fitted both Ultegra and XT hollowtech bottom brackets and the bearing races on both sides should very definitely move! There is a plastic 'pipe' type thingy that sits inside betwen the two cups to keep any inside-frame dirt and water away from the bearings, have you maybe got this misaligned somehow so it is fouling one of the bearings? I'd be inclined to take it right out (remember one side has a reverse thread), check everything, and start again. In some cases you need spacers between the frame and bottom bracket, and you need the right thickness and number on each side, so again check this against the manual (Shimano's site is good, it will be up there).
 
I've rrmoved the cups and the plastic pipe and there's no movement at all. I'll order a replacement. Thanks Tony.
 
As Tony says.

In the old days BBs were serviceable items, but Hollowtech confirmed them as replaceable (well, you can get refreshed bearings, but they're not designed to be serviced).

I used to love getting my bikes in fine fettle..! Sadly it was usually at midnight the night before a big day out so the pleasure didn't last long....
 
My Dad taught me how to change a bottom bracket when I was 12 with the old Campag spanners. Times have changed since then.
 
just had a look at this 4600 hologram stuff. sealed unit! plastic ! for gods sake forget all this modern crap and get some bloomin ball bearings, plastic ! i have never heard the like. get a 30 year old bearing out of the tip.
Rgds
Stuart
 
The better ranges, Ultegra, XT etc are metal. Might be worth upgrading; you can I think use Tiagra chainsets with an Ultegra BB.

PS Ultegra is damn good stuff, I have a 6700 chainset and BB that largely survived being run over by a Renault Master van and is actually the only reason I still have a left foot!
 
The Dura Ace press-fit bottom bracket is plastic around a metal bearing. Works very well and seems to last for ever.

I wouldn't casually write off any Shimano engineering at any price point.

Paul
 
What's wrong with plastic if used in appropriate settings ? All pro peloton bikes are made of plastic.
 
just had a look at this 4600 hologram stuff. sealed unit! plastic ! for gods sake forget all this modern crap and get some bloomin ball bearings, plastic ! i have never heard the like. get a 30 year old bearing out of the tip.
Rgds
Stuart
I think you'll find they're a metal race in a metal cup with a one piece plastic face and shim into which you slide the crank axle.

Be careful inserting the axle as it's easy to trash the shim. And don't overtighten the plastic hollowtech fixing bolt inside the axle - it needs to be just over finger tight.
 
When these things first came out the number of rides cut short on our Wed night jaunt in the Lakes hills was many due to seized external Bb's, I've no doubt they have improved with time but I still have a stash of internal Bb's and I think they are still available fairly cheaply.
 
I've been very happy with Shimano UN55 square taper BB - but I realize I'm about 20 years behind the curve on bike technology
 
When these things first came out the number of rides cut short on our Wed night jaunt in the Lakes hills was many due to seized external Bb's, I've no doubt they have improved with time but I still have a stash of internal Bb's and I think they are still available fairly cheaply.
Race face external hollowtech bearings were hideous in this regard, Shimano stuff is far better. They all like regular greasing and don't like being immersed in water - the only time I've had a Shimano bb fail prematurely was after a ride round the Elan lakes on which I was axle deep in bog for much of it.
 
Agree on Shimano I find it good kit. All my internal BB's are Shimano as is most else, I use sram chains though. I'm with Sean99, I don't update for the sake of it, these new drive trains amuse me single on front huge cassette then you don't get the same high gear for the down hills all to save a little weight I presume. Summer is coming :)
 
Agree on Shimano I find it good kit. All my internal BB's are Shimano as is most else, I use sram chains though. I'm with Sean99, I don't update for the sake of it, these new drive trains amuse me single on front huge cassette then you don't get the same high gear for the down hills all to save a little weight I presume. Summer is coming :)
:) 2x10 & 3x9 here. Both 26".
 
:) 2x10 & 3x9 here. Both 26".

My three are all 3x9. Had a shock though shimano internal BB's seem to be out of production they are the only octolink AFIK but there seems to plenty around have ordered 2 to increase my stash. I like the hollow axel can put the removal tool on and pass a long bolt through it, adjustable spanner 3 foot long scaffolding bar on spanner they always come out, never failed no matter how corroded.
 


advertisement


Back
Top