External BB bearings - worn?

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Stevek76
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Joined: 28 Jul 2015, 11:23am

Re: External BB bearings - worn?

Post by Stevek76 »

Tightening the two pinch bolts will do nothing for side to side play of the whole crank set.

There is a preload nut thing on the non drive side that you tighten first that is there to remove side to side play before doing up the pinch bolts. Similar idea to standard threadless headsets in a way.

This nut is a specific tool (though it often comes with an external BB spanner) but a big flat screwdriver might do in a pinch. The preload is not supposed to be done up tight, the tool has a ~ 2.5cm grip to be done only finger tight. However if there's filth between the cranks and the BB then some of that may need to be cleaned out first.

Watch out for the thin rubber washer/seal on the non drive side, can easily go missing when you take the crank off.

External bbs are generally badged as disposable and not to be serviced, but if you're careful you can pop the caps (these can be brittle) & bearing seals off and rinse & refresh the grease periodically to extend the life.

Last time I bought a road external BB, the adaptor to reduce the spanner from MTB size came with the BB.

Re torques, I'm a no torque wrench person but it's something like 1nm for the preload and a bit over 10 for the pinch bolts (so careful if you've just done those up really tight to try and solve the issue!). BB itself is quite high at 30ish though I've often not gone all the way on that, the whole point of English thread directions is it tightens as you pedal.
The contents of this post, unless otherwise stated, are opinions of the author and may actually be complete codswallop
nsew
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Re: External BB bearings - worn?

Post by nsew »

Sweep wrote: 24 Oct 2021, 9:44am
nsew wrote: 23 Oct 2021, 4:49pm
Sweep wrote: 23 Oct 2021, 3:09pm
Part of the reason I checked is that I had a "soft crash" recently - ended up in a bit of a heap on a grass verge after failing to take a bend in the wet :(
The front brake is set up for that sort of thing to happen. Turn the adjuster at the lever out (CW) a few turns - loosen off the cable and re-tighten with the pads against the rim - turn the adjuster back in (ACW) until the wheel spins freely. The objective is to get the vertical edge of the cantilever arms parallel to each other for maximum braking performance (MA).
cripes that is a bit of detective work - appears to be the bike in question.
The brakes are essentially as set-up by Hewitt (as I said I haven't done tons of miles on it) though obviously the pads have worn with my riding.
Will check things out - thanks.
Must say I prefer V brakes.
If I'd been more switched-on when buying the bike I would have specced V brakes and a square taper crankset - I still feel these possibilities should have been put before me as an option.

as for the crash - a bit complicated - a very bad downhill bend in the wet.
Park Tool how to.

https://youtu.be/FvFira2dAPY
David9694
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Re: External BB bearings - worn?

Post by David9694 »

You’re going to need the b/b tool to remove the external bearings, which as has been said should come with a tool that fits the plastic preload. MTB and road are different, IIRC. Both are plastic, you do up the preload up by hand are far as you can get it.

Don’t overthink the torque wrench thing. Make sure that the external bearings work, are in tight and the r/h crank is shoved all the way in - try a tap with a rubber mallet. Install l/h and its pre load. There’s some funny old clip I’m the gap that has to be pushed down (needs to be up to get the crank on) and then you’re ready to tighten up the bolts - you’re meant do to do a bit on each one - they don’t need super-strength. That should all be be sound.
Spa Audax Ti Ultegra; Genesis Equilibrium 853; Raleigh Record Ace 1983; “Raleigh Competition”, “Raleigh Gran Sport 1982”; “Allegro Special”, Bob Jackson tourer, Ridley alu step-through with Swytch front wheel; gravel bike from an MB Dronfield 531 frame.
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NUKe
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Re: External BB bearings - worn?

Post by NUKe »

Sweep wrote: 23 Oct 2021, 12:58pm

Another question - will also look particularly nooby, but I don't have a full set of tools with this bike and so can't easily at the moment take things apart to have a look - fair to assume that even though this bike was fitted with external bearings from the beginning by Hewitt that a full set of threads are in the BB shell so that I can i time replace the questionable external bearing jobbie with a square taper? (I have standing by a good quality Deore square taper crank set which I think is a very near relation of the DE ore external BB in there at the moment.
I hate the modern bearings, there another of those spill over from racing. they purport to give more torsional stiffness, so what. it nothing your average rider is going to notice, same weight wise . main downside outboard bearing don't last anywhere near as long.
NUKe
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Stradageek
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Re: External BB bearings - worn?

Post by Stradageek »

Stevek76 wrote: 24 Oct 2021, 2:44pm This nut is a specific tool (though it often comes with an external BB spanner) but a big flat screwdriver might do in a pinch. The preload is not supposed to be done up tight, the tool has a ~ 2.5cm grip to be done only finger tight. However if there's filth between the cranks and the BB then some of that may need to be cleaned out first.

Re torques, I'm a no torque wrench person but it's something like 1nm for the preload and a bit over 10 for the pinch bolts (so careful if you've just done those up really tight to try and solve the issue!). BB itself is quite high at 30ish though I've often not gone all the way on that, the whole point of English thread directions is it tightens as you pedal.
I did get a little worried about getting the pre-load correct so just used an Allen key (FSA cranks) with a carefully calculated load hung on the end - my torque wrench didn't go low enough. Worked well and left me more relaxed :D
slowster
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Re: External BB bearings - worn?

Post by slowster »

Sweep wrote: 23 Oct 2021, 12:58pm Does this mean that the bearings are worn out and need to be replaced?
If the bearings are damaged, see the following threads:

viewtopic.php?f=5&t=79765 (as always, see especially Brucey's various posts)

https://singletrackworld.com/forum/topi ... ring-size/ which mentions the following ebay seller:

https://www.ebay.co.uk/itm/281759194468?

The article below illustrated with photographs seems to correspond to the description of how to remove the bearings in the singletrackworld thread:

https://www.mountainbikerides.co.uk/fet ... ement.html
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geomannie
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Re: External BB bearings - worn?

Post by geomannie »

NUKe wrote: 25 Oct 2021, 9:53am
Sweep wrote: 23 Oct 2021, 12:58pm

Another question - will also look particularly nooby, but I don't have a full set of tools with this bike and so can't easily at the moment take things apart to have a look - fair to assume that even though this bike was fitted with external bearings from the beginning by Hewitt that a full set of threads are in the BB shell so that I can i time replace the questionable external bearing jobbie with a square taper? (I have standing by a good quality Deore square taper crank set which I think is a very near relation of the DE ore external BB in there at the moment.
I hate the modern bearings, there another of those spill over from racing. they purport to give more torsional stiffness, so what. it nothing your average rider is going to notice, same weight wise . main downside outboard bearing don't last anywhere near as long.
Tell me about it! Back to square taper.
geomannie
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cycleruk
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Re: External BB bearings - worn?

Post by cycleruk »

I like the engineering principle of Shimano outboard BBs. Very easy to service. I have had mine now for a good few years but don't really know how many miles they have done. I also have a bike with Campag' "Ultra Torque" BB and that's a different kettle. The bearings are a pain to change compared with Shimano's version.

Maybe the sealed cartridge lasts longer but can be awkward to remove/renew besides making sure you get the correct size etc. But each to their own. :roll: :wink:
You'll never know if you don't try it.
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Sweep
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Re: External BB bearings - worn?

Post by Sweep »

slowster wrote: 26 Oct 2021, 1:39pm
Sweep wrote: 23 Oct 2021, 12:58pm Does this mean that the bearings are worn out and need to be replaced?
If the bearings are damaged, see the following threads:

viewtopic.php?f=5&t=79765 (as always, see especially Brucey's various posts)

https://singletrackworld.com/forum/topi ... ring-size/ which mentions the following ebay seller:

https://www.ebay.co.uk/itm/281759194468?

The article below illustrated with photographs seems to correspond to the description of how to remove the bearings in the singletrackworld thread:

https://www.mountainbikerides.co.uk/fet ... ement.html
thanks for that slowster - will read through it all before posting any more questions.
Sweep
gxaustin
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Re: External BB bearings - worn?

Post by gxaustin »

I suggest withdrawing the crank spindle to check that it isn't worn. Feel the bearings to check they are smooth. Then reassemble. Use a torque wrench if you have one - why not?
It's probably nothing. I have experienced the preload nut coming loose and the crank working its way loose too, even though torqued up. I tightened it all back up a touch more and it has not recurred.
My push in external BB lasted 16,000 miles BTW. They are not as bad as they are made out to be.
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Sweep
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Re: External BB bearings - worn?

Post by Sweep »

gxaustin wrote: 29 Oct 2021, 11:47pm I suggest withdrawing the crank spindle to check that it isn't worn. Feel the bearings to check they are smooth. Then reassemble. Use a torque wrench if you have one - why not?
It's probably nothing. I have experienced the preload nut coming loose and the crank working its way loose too, even though torqued up. I tightened it all back up a touch more and it has not recurred.
My push in external BB lasted 16,000 miles BTW. They are not as bad as they are made out to be.
thanks - will get down to it once I get the tools to where the bike is and then report back.
Must say I am not aware of any symptoms when riding or turning the cranks with the bike turned over.
Sweep
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Sweep
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Re: External BB bearings - worn?

Post by Sweep »

nsew wrote: 23 Oct 2021, 4:49pm
Sweep wrote: 23 Oct 2021, 3:09pm
Part of the reason I checked is that I had a "soft crash" recently - ended up in a bit of a heap on a grass verge after failing to take a bend in the wet :(
The front brake is set up for that sort of thing to happen. Turn the adjuster at the lever out (CW) a few turns - loosen off the cable and re-tighten with the pads against the rim - turn the adjuster back in (ACW) until the wheel spins freely. The objective is to get the vertical edge of the cantilever arms parallel to each other for maximum braking performance (MA).
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well I was going to ask when you first posted, but now rather more inclined to after another of your, er, rather individual, and critical posts - so here goes - can I ask where you got that pic?

It does look as if it may be my bike but I post very few pics on here and I don't recognise that pic as taken from anything I may have posted.

Or is it time to play the spookey music?
Sweep
nsew
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Re: External BB bearings - worn?

Post by nsew »

The photo is yours, posted to this forum on the Leeds & Liverpool Canal thread a few weeks ago. I was going to point out your error at the time but thought it better to wait until you came off the bike. You’d need a brake lever with two feet of leverage to stop with that set up. Have you fixed it yet or have you adapted to use your feet?
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Sweep
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Re: External BB bearings - worn?

Post by Sweep »

nsew wrote: 5 Nov 2021, 7:33pm The photo is yours, posted to this forum on the Leeds & Liverpool Canal thread a few weeks ago. I was going to point out your error at the time but thought it better to wait until you came off the bike.
Charming. I see you haven't changed.
The reasons I crashed were:

Appalling weather/heavy rain
Very extreme descent
Very bad bend
Very bad camber
Possible debris/slippy stuff on the bend - thankful that I had survived I didn't waste time in very bad conditions on a blind bend to examine this in detail.

Me not anticipating the road enough

This last reason is the clincher and luckily one I can have more control over in the future if I learn the lesson - though an experienced cyclist who is always careful to not let the bike "run away" on bad descents with uncertain bends and surfaces I was caught out by being a bit worn from the weather/poor visbility and not paying close enough attention to the GPS which should have alerted me to the sheer extremity of the bend coming up. By the time I realised that more braking was needed it was quite simply too late - not a position you should ever put yourself in of course. More braking and I would simply have skidded. Maybe I even did a bit - it all happened very quickly.

nsew wrote: 5 Nov 2021, 7:33pm You’d need a brake lever with two feet of leverage to stop with that set up. Have you fixed it yet or have you adapted to use your feet?
Later in the ride I came down the not insubstantial slope of Pendle Hill (I know that terrain very well, as does the Hewitt) and I didn't have to deploy a 2 foot lever. Descending Pendle another way I know a lesser descent and bend that even on my best braked bike I would come off if I was lax enough to do what I did earlier in the that ride.

Since you are so concerned for my future well being I can tell you that I haven't seriously adjusted the brakes on the Hewitt yet as I am not with it and there is other stuff I need to see to on it before I ride it again. (not just the bearings)

I will do some tinkering with it in the future.

I may even at some point in the future put a V brake on the front - I have an idea that the bike's levers will pull both V brakes and cantis with a simple adjustment (but will of course double check) and am no slave to any rulez - I have set up three complete sets of V brakes on builds from scratch. I have a some new Vs sitting around and a ton of cheap pads.

I will also of course, helped by the kind folk above, double check the bearings on that bike.
Sweep
nsew
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Re: External BB bearings - worn?

Post by nsew »

World champion obfuscation.

Note how the cantilever arms aren’t splayed outwards and the pads sit close to the rim.

To release the arms for wheel removal, turn the barrel adjuster on the lever anti clockwise to slacken the cable, press the arm in towards the rim and pop the cable out at the quick release (where the mechs hand is).

All the information needed is in the Park Tool video here https://youtu.be/FvFira2dAPY

https://www.tektro.com/upload/Product/F ... BhVJtz.PDF
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