Hollowtech II bottom bracket - Any differences?

[Road_Runner]

My bottom bracket is on it's way out. When i stand up and power along, it crunches worst than Crunchy Nut cornflakes and gives the standard feeling that the bearings have gone.

So my question is, i have the FC-3450 crankset. The bottom bracket is a Hollowtech II style. Are all Hollowtech II bottom brackets compatible with all cranks with Hollowtech II bottom bracket axles attached? Do the bottom bracket axles differ in diameter? Is there anything else i should be concerned about other that the shell diameter and thread style. Do road bikes tend to have Italian or English threads?

My current bottom bracket has BC1.37x24 printed on the outside. Am i correct in believing that this indicates a 68mm shell diameter? (As highlighted on this Ultegra bottom bracket - http://www.chainreactioncycles.com/shimano-ultegra-6700-6703-bottom-bracket/rp-prod38998)


I've never had a Hollowtech II bottom bracket before this bike and it's the first time i've had to change it, so i don't know the small variations between components that can ruin your day when repairing your bike if you just happen to have purchased the wrong one. I'm only used to the sealed cartridge bottom brackets like shown here - http://www.chainreactioncycles.com/shimano-un55-square-taper-bottom-bracket/rp-prod71369)
So my main concern about choosing the wrong one comes from Chain Reaction's website. In a couple of their Hollowtech II bottom brackets pages, the description states that the component is actually required for certain groupsets. Like shown here - http://www.chainreactioncycles.com/shimano-5700-105-bottom-bracket/rp-prod50450 and here - http://www.chainreactioncycles.com/shimano-ultegra-6700-6703-bottom-bracket/rp-prod38998). Which makes me think there is subtle differences between the bottom brackets?


Thanks for the help in advance.

 

[byegad]

Not sure about compatibility but the HT II is very short lived. My much pampered example, never wet* or abused lasted 4500 miles. By comparison my traditional inside bearing BB on my Thorn Club Tour, used as an all weather commuter, did well over 10000 and was as good as new.

*It lives under a fairing on a recumbent trike so it's above the front wheel and gets zero road spray and no falling water on it.

 

[I like Skol]

I can't confirm compatibility issues but have noticed Shimano are very strict in specifying a certain BB to go with a certain chainset. However this didn't stop me upgrading from the Deore to an XT item. I think the last one has lasted much longer due to actually being installed correctly as I found out the original that was fitted at the factory was short of spacers and the left hand crank was bottoming out on the splines before making contact with the bearings. Unfortunately I replaced it the same way without realising and only spotted the error when fitting the XT items. The first two lasted approx 2k each while the current one has done over 5k at the moment.

See HERE.

 

[winjim]

A Hollowtech II is a Hollowtech II essentially. Make sure you have the correct thread, probably English, and you should be good to go. They are compatible between ranges - I have an Ultegra BB with a Sora crankset.

 

[djb1971]

Road and mountain are different widths due to the mountains longer axle. If you're using an mtb chainset get a mtb bb, if not get a road bb. Or upgrade to a hope.

Edit. Just noticed you're running a sora, get a 105 bb.

 

[djb1971]

http://www.merlincycles.com/road-bike-bottom-brackets-44198/

 

[srj10]

What are the benefits of the various options,tiagra v 105 v ultegra? I have a tiagra that needs replacing soon.

 

[Road_Runner]

Thanks for the advice fellas.

srj10 - The only benefit that i'm aware of is the weight of the component.