What will replace the quality of the discontinued Shimano BB-UN55?

[silva]

Just get a UN300 - no problems from mine and they aren't expensive. Far better than GXP etc. Stop faffing.

What is the length of your axle?

 

[Ajax Bay]

What is the length of your axle?

All lengths available:
https://www.sjscycles.co.uk/bottom-...l-square-taper-bottom-bracket-english-thread/

 

[silva]

All lengths available:
https://www.sjscycles.co.uk/bottom-...l-square-taper-bottom-bracket-english-thread/

That's not what I ment.
With same bottom bracket parts, a longer axle may bring problems whereas a shorter axle doesn't, due to leverage, due to cranks position further away from axles support / bearings.
A comparison good/bad for the job, should axle length into account, no?
My 122.5 mm axle length requirement may require better suited materials to achieve a same life as a shorter axle.

 

[fossyant]

You get the correct axel for your chainset - length can vary depending on the chainset/crank design. My Deore LX takes either 110 or 113mm, 113mm being the recommended length. Axel length is more important for chain line than any worries about strength etc.

You are overcomplicating things. Just get the correct length for your chainset to achieve the best chain line. Too long or too short will compromise this and make shifting worse.

 

[silva]

You get the correct axel for your chainset - length can vary depending on the chainset/crank design. My Deore LX takes either 110 or 113mm, 113mm being the recommended length. Axel length is more important for chain line than any worries about strength etc.

You are overcomplicating things. Just get the correct length for your chainset to achieve the best chain line. Too long or too short will compromise this and make shifting worse.

It's not about a "best" chainline, but one that is sufficient, by means of a longer axle, to avoid chainring conflicting with frame, at new chain mounted, tensioner being eccentric module within frame, where bottom bracket goes through..

 

[Ajax Bay]

With same bottom bracket . . a longer axle may bring problems . . . due to cranks position further away from axles support / bearings.
A comparison good/bad for the job, should axle length into account, no?
My 122.5 mm axle length requirement may require better suited materials to achieve a same life as a shorter axle.

Nope. The UN-300 axles are steel and entirely fit for the job. As are the Stronglight ones.
What material do you think will better suit your imagined 'special' requirement? Life of a cartridge BB depends on the bearings, not the steel axles which are more than adequately stiff.
As another said: stop faffing.

 

[FrankCrank]

Could always replace worn bearings


View: https://www.youtube.com/watch?v=meErJdr_fUI&t=366s


Think of the satisfaction gained from not throwing away a mostly reusable component.

 

[Ajax Bay]

Could always replace worn bearings
Think of the satisfaction gained from not throwing away a mostly reusable component.

Have you sought such satisfaction, Frank or is this just your wild imagination getting out of hand?
https://www.kineticbikebearings.com/163110-2rs.html
Two bearings for <£16
Bearin mind (swidt) that the UN-300 spindle is 17mm so 6903s.

 

[FrankCrank]

Have you sought such satisfaction, Frank or is this just your wild imagination getting out of hand?
https://www.kineticbikebearings.com/163110-2rs.html
Two bearings for <£16
Bearin mind (swidt) that the UN-300 spindle is 17mm so 6903s.

I ordered two sets of bearings, fair to say they are cheapo unbranded.
I plan to attempt this later this year when we get into the 'cool' season.
I will of course share on here - that's what it's all about.
Satisfaction is not guaranteed

 

[fossyant]

Interesting that the bearings are replaceable - they weren't on the older models. I've got two UN300's for the commuter, so if the existing one fails, I may try a repair after replacing it with my spare.

 

[silva]

Nope. The UN-300 axles are steel and entirely fit for the job. As are the Stronglight ones.
What material do you think will better suit your imagined 'special' requirement? Life of a cartridge BB depends on the bearings, not the steel axles which are more than adequately stiff.
As another said: stop faffing.

It wasn't about the material of the axle but of the material holding it in place.
The further crank sits from its bearing, the more load on the axles bearings and mating surfaces towards the frame.

Weakers materials can lose material, that is, free space, that is, movement, that is, grinding off more material, accelerating the removal of material;
Squeek squeek till failure.
Dealers mechanic experienced UN-300 as quite less lasting than UN-55 so ceased to propose UN-300 as a first.
Instead, Stronglight JP-400, but since I have had bad experience with a crankset of them, I'm wary.
It's not sure Stronglight makes these themselves though.
I found in a single search already 2 reports about them rebranding, one being a Neco, the other a Kinex Slovakia while the latter had on its box "Made in France". So if you order a Stronglight JP-400, you don't know what you get - it's a bread in a bag with the name of its seller not its baker.

 

[fossyant]

Look, they work fine and can be picked up for £15-£17 quite often (replacement bearings alone cost this). No issues with mine and it's ridden in all weathers. You don't half get carried away looking into stresses etc etc, when it's a non-issue.

Are you sticking it on that bike in your avatar ?

I'm running two cartridge BB's that are over 30 years old, a UN71 and a UN91 (which is about £75 used these days)

 

[silva]

Yes frame broke, new frame, so unmounting bottom bracket/crankset, decided to not risk the Octalink design flaw lack of press fit of left crank, reappearing again, a suddenly losening crank on a bad moment is a recipe for disaster.

Decided back to square taper.
- 47 mm chainline distance
- gear 47/16
- gear fixed so also uphill + headwind.
- heavy bike - heavy load
- resisting pedals to slow down so also opposite oriented force on cranks and their mounts
Something to take into acount, since for ex cranks at drive side have clockwise tensioning while nondriveside anticlockwise tensioning, and resisting a pedal is then losening direction instead of fastening direction. So tensioning enough from the beginning, don't rely on further tensioning by pedaling. It could be a forth and back until cranks pedal eye thread ruined, which may have been 1 cause of the breaks I suffered with the Stronglight cranks, the other cause these having less thread due to thinner. The less thread makes thread damage easier, and also losening easier. It all acts towards failure, adds up to achieve it, take away one element and it works for 1 but doesn't for another.

Which may make that yours run for you that many years/km but less for me.
And since lost material aggravates it, exponential factor, that less can be alot.

 

[fossyant]

Sorry, but I hammer my bikes. Used to get 12-18 months out of a UN55. So far this UN300 is holding up well. You aren't Chris Hoy you know. Any BB will be way stronger than you are. What fails is the bearings due to ingress of dirt and water.

Octalink was a crap design and we kept telling you to get rid. Square taper is fine, and these cartridge units are very robust and long lasting.

 

[fossyant]

PS I'd rather have a Shimano BB than any of the others. You really can't go wrong for £17 (Merlin).