[Closed] square taper vs external bb

Just worth mentioning but most people over tighten their cranks onto the BB (assuming Shimano type HT2 cranks) which causes the BB to die much faster. You should tension them just enough to remove the play.

I'm using both types and they seem to be lasting well for me. I use UN54 on the square taper and they're ridiculously good value - hollow axle and £14. They do use the plastic lock ring but I've never had an issue with that and you could always get a metal one from an old dead BB.

If you go square taper, get something like a RF turbine crankset from the classifieds - I paid £35 for my last set.

On a personal note, I would say invest in a decent BB, even XTR has lasted noticeably longer for me over an SLX/XT version. Got a king BB in my cross bike and it's outlasted 2 pair of shifters, 4 tyres, 3 mechs and 3 chains and cassettes.

My main reason for this is that the 2-pc crank interface and hollowtech design is noticeably stiffer than a sq taper set-up, on a SS bike where there will be instances where you will be generating a lot more torque through the cranks it will be more efficient overall.

octalink?

I'd agree that HT 11 is a lot stiffer than sq taper and Alivio isn't the stiffest square taper crankset to start with.

do people really notice a real world difference in stiffness in a crank,
i struggle to feel anything,

the new un55 comes with a ali non side cup

octalink and isis were good in idea but in practice not the best,
bearing were far too small to accomodate the large axle,
remember seeing someting on superstar components where they managed to fit large bearings into a isis bb and therefore potentially solving the above problems. but i wouldn't trust a superstar bb to be honest

[i]do people really notice a real world difference in stiffness in a crank[/i]

I think I do yes - all feels slightly more direct when you're really pushing - especially singlespeed.

Have not experienced any issues with the Octalink ES51 on one of my bikes. It just keeps going round and round and round and round...

We are talking years here, min 6000 off-road miles.

You can feel it. Whether it actually makes any difference out on the trail is the real question...

Yeah, not had good experience with Octalink - mangled the splines! Like the idea of the simplicity/reliability of square taper re 'Clubbers' experience. I see that Rose bikes has XTR bb for about £15, maybe I'll give those a go for now.

Didn't one of the mags measure stiffness in the early days of HT2 and found even saint was <100% stiffer than a basic ST crank?

I only run HT2 on one mtb as the STs kept creaking on jumps etc.

not had good experience with Octalink - mangled the splines

I build and ride retro road bikes, using mainly Campagnolo parts i've also got a modern 853 road bike with Campagnolo Record 11 on it.

I can tell no difference between Campagnolo Record (sq taper) of 30 yrs ago and the modern carbon equivalent.

octalink has decent size bearings in it - Most of my bikes are on octalink and bbs last a long time. the higher quality octalinks BBs are no longer made tho

remember seeing someting on superstar components where they managed to fit large bearings into a isis bb and therefore potentially solving the above problems. but i wouldn't trust a superstar bb to be honest

The STW consensus is that the SS ISIS BB is actually very good. Was certainly my experience before I started using HTII.

The trick is that it doesn't use cartridge bearing, but larger loose bearings.

Whilst I agree that over tightening HT BBs is usually the cause of failures as I've done it myself, I changed to UN 54 and Middleburn cranks a few years ago and I'm sticking with them.

Square taper - I have them on my two ss bikes, road and mtb and haven't noticed any lack of stiffness - HTII, a solution looking for a problem imho.

I can tell the difference between HTII (Hope BB) and my square taper BBs and even octalink, having been through all on the same frame - I'm not normally fussy either. It's most noticeable between bikes bu this could easily be the frame flexing.

UN52 and Hope HTII have been best so far, I used to ruin octalink in 6 months for some reason. The Hope is ceramic though, I guess this should equate to greater longevity.

Problem Solvers will be gutted the UN55 has an alloy cup - they were flogging their own as a replacement for the UN54 plastic one for £15!

I replaced the crap square taper BB that came with my bike last year for a UN55 (metal lockring cup)which I expect to run for a very long time.

Real World Cycling do their own external BB's which have just been updated to angular contact bearings, £60 with postage so not cheap but they're meant to be good > http://www.enduroforkseals.com/id198.html

I still think HT2 sort of missed it's own point a bit, quite why they had to go for a 24mm axle I still can't see.
3/4" would have been perfectly workable, for MTBs (it certainly is for BMX) and combined with external bearing BBs we could have had a much more robust MTB BB, increased stiffness over ST and everyone would have been a winner...

As it is we're still lumbered with relatively thin section bearings, which was one of the original problems with ISIS and Octalink that HT2 should have solved...

Thanks guys. So if I wanted to go square taper, what reasonably priced cranks are available?

do people really notice a real world difference in stiffness in a crank,

Going for ExtBB on my mtb now,however I had no probs with the octalink crankset that was on before.

I run both. The external BB;s never last as long as a similarly priced square taper. If it was not for the expensive cranks that take external BB's I would switch over to square taper. Like many many things bike modern solutions are often not a dura as the tried and tested retro solutions.

I would stick with square taper and the Shimano UN54 or Un55 is a very cheap and relaible BB.

As for the Alvio cranks they only thing in favour of them is they are £40 cheap (don't pay more than that, I sell them for that) and they have seperate chain rings. I would if you have the coin pick up an old set of XT cranks or Race face turbines from ebay or retrobike.

i run xtr with a hope external and a deore with a square taper on the SS
I dont notice any difference on stiffness

^^ Exactly

alivio £31 on crc at the mo, personally I'd save for a set of middleburns...

I thought I was just me that didn't really have a problem with square tapers! I'm not an early adopter. I only went Octalink last year!

I've got UN 54 on one bike and can't see any problem with them other than weight. The present on is on it's second winter of off road commuting and the previous one lasted 3 years before becoming a bit rough. I think it's a real pity there isn't something between the UN55 and the likes of Royce. I'm sure plenty of people would be more than happy to see the return of the UN72.

Not used them but the TA Axix sq taper BB's look pretty good,available in steel and ti versions,see Dotbike
http://www.dotbike.com/p/139

I also got sick of going through external BB's and considered going for CK external BB and grease gun after having good experience with CK headsets following going through headsets too quickly years ago.

To be honest, the price of the CK BB's put me off so I went for a Shimano UN54 internal square taper BB and Middleburn cranks.

That was a year or so ago. Still feels lovely and smooth and has now outlasted any of my external BB's by about 6 months with no sign of it dying just yet.

Oh god, so maybe its Middleburns and square taper then?!

No regrets after I went the Middleburn route. People complain about shifting but I can honestly say I love my set up and have had no shifting issues to date.

Not sure you need to bother with the Middleburn Hardcoat rings. Just get standard ones. Hardcoat wears off dead quick, apparently.

Thanks coolhandluke, they'll go on a ss build so shifting not an issue.

Middleburn, Royce, on the geared bike and s/s 😉

Super reliable. If it ain't broke.....

I notice the flex in a Hollowtech octalink setup compared to a HTII setup.

I do think the biggest problem is people not setting up HTII cranks properly. They have a plastic pre-tension bolt for a reason but yes compared to square taper and octalink where you just tighten the end bolts they are more open to installer error.

A lot of people complain that external BBs don't spin freely. That is only the case on brand new BBs or ones that have been fitted badly.

Middleburn and Royce on both singlespeeds and Nicolai, no problems just fit and forget, no discernable lack of stiffness imo, but I do only weigh 10.5 stone

I can tell no difference between Campagnolo Record (sq taper) of 30 yrs ago and the modern carbon equivalent.

This is probably because its hidden due to the amount of flex in these old road frames. No matter what chainset and bb unit is in there, its going to be buckling around under load. On a stiff mtb frame ht2 is noticeably stiffer.

Infact its also noticeable in another way (without going by feel)
I have noticed many times on both road and mtb upgrades that the front mech set up can be adjusted easier as theres not as much chainring movement once you take the bike on a road test. It might shift fine on the workstand but sometimes you have to wind the mech out a tiny fraction more with an older set up as its unaceptable to ride (when under load on the drive side)
With HT2 you can adjust the mech on the workstand and its more than likely it'll be stiff enough under load to also be rideable in the big ring. No extra fraction further out to keep the customer off yer back.. its stiff enough to set up as close to the chain as possible and you can be confident that the flex wont cause you problems.

I have noticed this on new bikes that might have had the upgrade,my own bike and numerous others over the years. Then you add a stiffer frame into it all with a fat downtube grasping the bb shell. HUGE difference compared to a steel frame with a square taper setup. Its all just moving along bit by bit.

So as more people go for a single ring set up at the front are the noticeable benefits of a stiffer BB less important?

I'd say crank stiffness probably more noticeable than crank-BB interface stiffness. That said, decent Shimano HTII cranks (SLX/XT) are very stiff. My Hollowtech 2 XTs are a bit stiffer than square taper Middleburns, which are in turn far, far stiffer than the cranks I had back in the day before those (FSA Powerpros?!).

I like HT2 - It's much nicer to set up and work on than square taper, and it's dead easy to replace the BB every 6 months or so. I've also had much better luck with XTR BBs lasting longer than SLX/XT. The XTR ones are only £15 ish from Rose bikes so that would be the best thing to try first.

I'd say crank stiffness probably more noticeable than crank-BB interface stiffness.

How would you know?