A friend retired from a trailquest yesterday (did I mention my friends ride trailquests too ?) because the left hand crank came loose on her Octalink chainset.
I had a look and the steel shaft looks OK, but the splines on the aluminium crank are completely fukushimad.
I could have a spare Hollowtech 2 chainset available if I swap bits around and put a spare Race Face chainset I’ve got lying around on Mrs MTQG’s bike.

So, I know it’s not the done thing to ask for price guidance on here, and I’ll do a bit of research to find out what second hand Deore chainsets go for in a minute, but what would be her best option;

Buy a brand new left hand Octalink crank arm and bolt ?

Buy my second hand Hollowtech 2 crankset at mates rates and a new external BB ?

Hollowtech 2 is lighter! You’d have to quantify better.

Her best option would depend on her particular needs, but a whole new MTB octalink crankset can be had for £20 from CRC (Shimano M443 170mm).

And this time make sure she gets her crank bolts done up tightly and threadlocked!

Octalink is crap. I just took one of Mrs Aches bike and put it in the bin. She now has a HT2 on there and I expect it to last a lot longer.

I have had nothing but problems with Sq taper, octalink and isis cranks but have never had a problem with HT2 ones. I find that even the BBs last me longer.

I have two bikes with octalink – I far prefer it to HT2. Lasts for years, just works

So, conflicting opinions on whether Octalink is better than HT2 then. 😕
That M443 at CRC look like good value. She wants it sorted in the next few days though, so it’s about £35+ for the 9 speed ones they’ve got in stock.
Does that include the BB ? It’s not clear from the description. I would guess not at that price.

HT2 complete chainsets are round about £70 new.

If it was me, looking at the splined interface, I’d go for a second hand HT2 and external BB over a brand new Octalink. It just looks like a stronger design.

I just got an email back and she took the bike in to the LBS to get the brake pads changed and they found a spare L/h Octalink crank arm, so it’s all sorted on the cheap now and she’ll be back out riding it tonight.

I meant to say earlier I’ve got divided loyalties here.
On the one hand, I don’t like to see a friend paying to have the most basic repairs done on their bike, I’d rather spend a bit of time helping to give them the confidence to do stuff on their own.
On the other hand, the guy at the LBS has always been very helpful to me and I don’t like to do him out of business.

could be interesed if u stillwant to sell the spare ht2 chainset u have?

I’ve run an slx HT2 for 12 months, every day riding with no issues at all.
The preload cap only needs finger tightness, any more overloads the bearings and they fail early…

Octalink loads better, but a little heavier. You can tell Octalink is better by spinning the cranks with the chain off. Octalink whirrs, HT2 sounds stickier and damped.

Ht2 BB’s don’t last anywhere near as long either. Think about it, for two seconds, please!

The bearings in an octalink or square taper BB are sat inside the bike frame and are protected from dirt and grit to some extent. Why anyone thought sticking something that vulnerable outside the bike, like on a HT2 BB, is beyond me. Although if you are selling BB’s it probably looks like a great idea.

I didn’t get on with Octalink – I had a similar issue with the non-drive side crank, to the point where I had to buy a replacement. Unfortunately, I think they’re getting a bit fewer and farther between these days, so if it happens again you might struggle for replacements.

I’m now on an XT HT2 crankset, and it seems OK so far (9 months or so).

Karnali, the chainset is still on Mrs MTQG’s bike and now the rush is over to help sort out a friend’s bike, it couldbe awhile before I get round to taking it off.

Why anyone thought sticking something that vulnerable outside the bike, like on a HT2 BB, is beyond me.

As I understand it, external BBs allow the use of bigger bearings spaced further apart, both of which should help reduce the load on the bearings.
It’s a bearing with a shaft through it with one side exposed.
It’s no more or less protected from dirt and grit whether it’s in the frame or external.

Sure merlin do th eDeore ht2 for about 49 quid with bracket.

2 Octalink chainsets doing me proud at the moment, can’t compare it to HT2 having never owned one, but my Truvativ equivalent (GXP?) fell apart pretty damn fast.

the bearings in octalink and isis bottom brackets are smaller than square taper to accommodate the larger axle, and that generally means they wear quicker,
however I have seen (I think on superstar components) an isis BB which somehow crams bigger bearings in.

I thought the main advantage of external bearings was to add stiffness to the crankset

I don’t know what that means to be honest,
I reckon I’m too weedy a rider to notice.

Never had problems with octalink or square taper, have had problems with HT11.

plenty of people install HT2 badly by either not facing the BB shell or, more often, putting too much preload into the bearings, both of which can significantly reduce the lifespan (and then criticize the ‘design’, when it fails 😕 )

A properly installed HT2 is equally as long lasting as octalink, and is a bit lighter and stiffer.

Octalink/square taper/isis will be favoured by the sit and spin/commuter/never leave the ground crew.

I say this because what is going to bother this crowd is bearing longevity. Stick a load of bearing sitting inside a nice shell keeping them all aligned, then sitting tucked a way in the bb shell, further away from dirts harm. The bearings only have to deal with pedalling loads, they’ll do this happily for ages.

Then tapered arm/bb axle interface only has to deal with pedalling loads, as long as the bolts are tightened regularly, will carry on it for ages.

HT2 will be favoured by the aggressive end.

Add in loads from doing drops/jumps/out of the saddle sprinting, the octalink/etc axles and arm interfaces can’t cope, they will give in.

Plus from a design and engineering view point HT2 is simply better. Lighter, stiffer, stronger, more efficient use of material. Small diamater, solid things are less efficient than big hollow things.

if you’re the kind of person that wants years from their bb, sit in the saddle and pedal, old style bb would work for you.

if you’re more aggressive, more concerned about power transfer and wanting your cranks in one piece after a ride, go HT2.

if you’re the kind of person that wants years from their bb, sit in the saddle and pedal, old style bb would work for you.

Really? My my, you’d better explain all that to the old, second hand when I fitted it, XTR Octalink in my rigid singlespeed, which I used primarily for thrashing around on rooty singletrack, standing and sprinting all the way, or maybe the equally old XT Octalink set up on my singlespeed CX bike, which is used for lots of sprints and wrenching up short steep hills (oh, and thrashing around on rooty singletrack).

In fact, maybe you’d better also explain that to all the downhillers who used exactly the same crankset (designed for XC racing remember) for downhill racing. 8)

HT2 probably is better, but that doesn’t mean Octalink was in any way lacking, and was definitely more fit and forget.

^Give me a octalink to ride, i’ll annihilate it. With downhillers running it in the past, they were just making the best of a bad bunch. What would the modern downhiller rather trust, an older octalink xtr or a modern hollowtech saint?

MTBs are limited by the stupidly small bb shell.

They have to go with internal/many bearings (can be longer lasting)/thin inefficient axle (old style, worse).

Or

Efficient (better) axle/cranks/poorer outbound bb.

It’s one or the other, with the current bb shell standard, this is it, there is no design capable of optimising in respect to both.

This is why all companies need to jump on BB30, (not this bb90 rubbish lapierre and other are pushing, but that’s another rant). Then you can have large press fit bearings that last for ages as well as a massive stiff axle to increase efficiency.

This is why all companies need to jump on BB30, (not this bb90 rubbish lapierre and other are pushing, but that’s another rant). Then you can have large press fit bearings that last for ages as well as a massive stiff axle to increase efficiency.

No… they need to jump on BB30 because they’ve run out of other marketing B.S. to push, so have developed yet another new standard that offers 99.99% of everyday riders (i.e. those of us who don’t annihilate cranks 😉 ) no apparent advantage other than having to buy a new frame, new cranks, and act as Beta testers for a few years until the manufacturers sort out the teething problems, or release a new standard.

Having used all 3 types over the years, I think im in a position to comment here.
Square taper generally last longer than Octalink and HT2, mainly because the bearings are tucked away and have larger bearings within, than compared to Octalink which has a larger internal diameter, but similar outer diameter bearing races, therefore the actual bearings are smaller.
But with HT the tapers can be overtightened, thus damaging the cranks.
Octalink have a larger diameter axle and splined interfaces, so are stiffer and the crank axle interface is pretty solid, but the bearing life is poor for reasons above.
HT2 have larger axle, larger bearings, but are more exposed than the traditional internal designs above, so they tend to be in the direct line of spray from the front wheel, so consequently they dont last as long.
I’d say the HT2 are a reasonable compromise between strength, stiffness and bearing longevity. Just depends what you want from a crankset/ BB really, bearing life or stiffness / strength.

But with HT the tapers can be overtightened, thus damaging the cranks.

I’ve been doing my square tapers up very tight since they were called ‘cotterless’. Never had an issue. Mind you, I do grease them first. I’ve also heard from respected sources who claim not to have enountered problems. Can you provide some first hand evidence of this? Not saying you are wrong, just curious.

I’ve had an Octalink on the HT for 7 years (on 2nd BB) and can’t tell the difference in stiffness once riding, weight either. When this BB fails, I won’t be rushing to change the chainset to HT2 as I can’t see any real benefit.

I’ve got a HT2 on the FS and I’d agree that HT2 probably is a simpler, better design, albeit let down by piss poor bottom bracket sealing. All this talk of facing and improper fitting just masks the fact that the BB’s are crap, with the best option being to ‘upgrade’ to a Hope/Chris King.

Unfortunately, I think they’re getting a bit fewer and farther between these days, so if it happens again you might struggle for replacements

Thought that too, but there’s quite a sizeable number of big brand name complete bikes which ship with a “budget” octalink BB+Crankset, but rest of groupset is a mix of SLX with an XT rear mech. Replacement BB’s might drop off the major aftermarket online stores, but they (and I’d expect Square Taper) should be available for a long time to come.

Never used octalink or isis, so can’t comment, but my HT2 has done abotu 1000 miles and is on the verge of feeling a bit “scrunchy”, but my OEM square taper is still sweet after a good 4000miles.

Press fit… hmmm not convinced yet. Should be quick/easy in mass production, on bikes that will never need a replacement. But for excessive tinkerers it just means trips to LBS for what used to be trivial task, or yet more tool purchase. Dunno how BB mount type chain devices and front mechs fit with pressfit?

I was looking for just this discussion! Might need to buy a chainset for the new commuter/cx/tourer type thing and the old 105 octalink chainsets are a steal. Look pretty, too.

Edit: If I do go down the Octalink road, what’s the recommended set up? grease on the splines and threadlock on the bolt threads?

Crank the bolts up really tight?

no apparent advantage other than having to buy a new frame, new cranks

I don’t want to nitpick a quality piece of ranting, but no-one’s forcing you to buy a BB30 frame unless you want one; if you do you don’t need new cranks either as there are plenty of adaptors about (I have at least one threaded BB to BB30 adaptor kicking about the garage).

Andy

The stiffness advantage of HT2 is a load of rubbish as well. It might be useful on a road bike or commuter, but a MTB has 2″ tyres at 40psi and usually several inches of suspension on one or both ends. Whether the BB flexes a few hundredths of a mm every now and again is utterly irrelevant.

dmjb4 i disagree, my octalink axel flexes more than a fractions of a mm ( i am abit of a biffer) i can see the chainring moving relative to teh front mech if im really stomping

ht2 is noticeably stiffer in an area where you are putting a lot of torque

Edit: If I do go down the Octalink road, what’s the recommended set up? grease on the splines and threadlock on the bolt threads?

Crank the bolts up really tight?

More or less, I’ve never been very rigorous with greasing the splines and haven’t noticed any problems. If its new kit then check the bolts after every ride for the first few rides, as the cranks bed into the splines they can loosen ever so slightly.