External BB and cranks

mastermosher

Are the new external bottom brackets universal in the way they fit the length of bottom bracket shells. I know that for my optimo frame it must be 68mm across.
I know that the others (ie sealed bearing units)are different lengths and if it was one of those i would need a 110mm/68mm.
Any advice would be appreciated.
Thanks

kegs

most HT2 etc systems are generic for 68/72mm BB shells, they use spacers to get the chainline correct.

You only need something specific if you have an extra wide (83mm) or narrow bb shell.

The installation instructions are pretty foolproof on the shimano systems.

mastermosher

Cheers Kegs, you have put my mind at peace.
What would people recommend as a crankset. My main concern is that I weigh 210lbs (thats 15 stones of muscle in english as I play rugby). I will replace the bb in the end with either a hope or superstar ceramic bearing model.

kegs

You can't really go wrong with either the shimano XT or SLX chainsets.

the SLX ones are around £80-£100, and you can get them in triple or double and bash versions.

XT is a bit more, £140 rrp, but merlin have them for £98 here, which is a cracking deal.

They also have the SLX for £75 for the triple and £85 for the double and bash.

Either chainset (or similar raceface/fsa/truvative ones) should be plenty rigid and strong enough for you, ht2 is a far more rigid system than square taper or octalink/isis systems

Anonymous

i am a big fan of the xt cranks, i got mine form merlin and think they are excellent, bear in mind, i am over 19 stone with a good breakfast in me and they havent missed a beat.

switchback18

I'd avoid HT2 personally, I've not had any BB that's lasted well. They seem to wear out really quick. I'm going back to ISIS & a set of Middleburn RS7 cranks.
HT2 looks like the best design, so I'm not really sure why they wear so quick, but I've seen so many bad ones that I've given up on it. I ride a fair bit as it's my job, but even in the old days of square taper axles, they used to last years instead of months/weeks.
I only weigh 13st.

supersonic

Yep, the older systems still have their place for many. Octalink is pretty stiff, to the point even heavy riders don't really notice it flex (still use HT arms). It baulks me to pay 70 quid for a chainset, with poor bearings, only to have to upgrade the BB to some 50 quid unit.

Worth keeping an eye out for old XT and LX octalink cranks. No need to face the frame either.

mastermosher

Unfortunately there are not many 110/68mm isis or octalink bb's around, unless anyone can reccomend somewhere or a particular brand. i have searched myself. Hence why i was asking about external bb's.

supersonic

The axle length depends on the chainset - LX for axample uses a 121mm BB for a 47.5mm chainline.

but yes, generally the stuff is getting harder to find which is a great shame.

CraigXXL

sheepsteeth wrote:

i am a big fan of the xt cranks, i got mine form merlin and think they are excellent, bear in mind, i am over 19 stone with a good breakfast in me and they havent missed a beat.

Do you feel any flex when you put the pressure on with the XT Chainset. Only reason I ask is I'm a similar weight to you and I feel the flex on the deore cranks fitted to my Avalanche 1.0. Not sure if it is from the pedal/crank interface, the bb/cranks or the crank arms themselves but don't find them confidence inspiriing.

Anonymous

none whatsoever mate, i used to have a couple of sets of the old xt ht2 as well and apart from the looks, they feel the same, super stiff, decent weight and price and from what i have read, the new xt has longer lasting rings.

Mancunianfightingcat

I think the ht2s wear out if the bb faces are not 100% parallel. With the ISIS system and HT1 both bearings come in 1 unit and are therefore guaranteed to be running parallel.

If you're fitting external bearings, then you must ensure that the bb shell is accuarte. It may only be out be 100th of a degree out, but every revolution of the cranks will put unnecessary strees on the bearings and quickly wear them out.

Simply put, if you're fitting external bb cups get the shell faced first.