From square taper to hollowtech II BB. Advantages?

[BigFoz]

Maintenance? What is this maintenance?

Campag Sq Taper with the sealed cartridge bearing, fit and forget. When I recently stripped down my 16yo Colnago for a refurb, it had the original BB in it (Record) which I can't recall ever taking out - it's always spun beautifully. While the frame was being repainted etc, I compared it to a brand new BB, and it was as good. It got cleaned, polished and re-installed as part of the rebuild, in spite of having a box full of spare BBs - I've been collecting them for when ST is no longer available in good quality. I have no idea how much mileage it's done as for the first 10 years or so it was my "best bike". However, the last 6 or so have seen it regularly used in all weathers as a commuter with a rack and guards bodged on. I don't religiously log miles, so I'm guessing, but the BB has to have at least 20,000 miles on it (Which averages to 1200 miles or so a year - which isn't a lot, so it could be a lot more than 20k!).

[meic]

Yes but if you prise open your old Tiagras and later I prise open my old FSA MegaExos and somebody else prises open their Dura-Ace we may find out if there is any real difference.

Hmm, maybe... thing is that unless they really are the same manufacturer etc they may not be the 'same thing' even if they have the same number on.

Most 'standard bearings' are available at different price points and although they should all be 'OK' (i.e. meet a certain minimum specification) the manufacturer's specs sometimes tell a different story.

edit: see here for some more bearing info:
http://www.diymtb.com.au/displayItems.asp?cid=14

I'll be interested to see what you find.

cheers

The bearings inside the FSA Mega Exo are these ones. 6805 2RS (probably 6mm)

They appear to be full complement having 30 balls and only space for one more and they also appear (using the dipstick part of my vernier gauge) to be 6mm rather than 7mm which would make them a good replacement for the Shimano bearings.
However holding an FSA Mega Exo alongside an Ultegra BB, the Ultegra looks quite cheap and nasty in comparison. The FSA seems a much better quality item, even before opening up the bearings.

[Brucey]

a full complement bearing ought to be stronger than a standard deep groove bearing in a low speed application like this. However the caveat is that if the bearing is liable to fail because of water ingress, it won't matter how many balls it has, once the water gets in, that is the kiss of death.

Hope and some others use stainless bearings which resist the worst effects of water rather better, even if (per ball) the bearings are not as strong as conventional ones.

Are the FSA bearings stainless too by any chance?

cheers

[georgew]

I've just stripped my FSA Mega Exo chain-set on a new (less than 100 miles) bike. Found rust emanating from the non-drive bearing already and also found to my horror that the BB shell had not been faced and the bearings had been tightened up over a thick layer of paint. This on a bike costing £1600.The bearings were almost impossible to undo as green loctite had been used (I wonder what this would do to the specified torque settings ?) I've now faced the shell, but as per my usual practice am now searching for a suitable square tapered chain-set to replace the original.

You may call me a Luddite but really......

[meic]

A hundred miles is pretty surprising and disappointing.

Mine had done over 6,000 and there was no sign of rust, the grease was inadequate, dirty and old looking and not really in the right place anymore.

The balls looked more like ordinary ones than stainless but hard to be sure in a race and so tiny. There was no sign of rust or water ingress and I think the roughness is due to running with inadequate lube.

These Mega Exo cups have 2RS seals on the actual bearings, the bearings themselves are sealed from the environment by an inner blue seal and at the outer with an O ring on a ridge running in a groove as in Erudin's link.

I like to think of myself as a bit of a Luddite too, this is still just a ball bearing mounted crank. I reckon that a lot of the problem is our lack of familiarity with it. This forum is full of advice on how to assemble and maintain traditional equipment with little sympathy for those who wreck it by failure to do such things. Hopefully in a few years such "folkwisdom" will have been collected for these bearings. It is already starting to be gathered.

Any real Luddite will still be using a traditional cup and cone axle. With Cotter pins!

[Brucey]

....These Mega Exo cups have 2RS seals on the actual bearings....

if they are full complement bearings with a loading slot, IME the seal on the side with the loading slot will be less effective than normal. In some patterns there is actually a gap at the seal edge, and the seal is more there to help retain grease than to keep water out. The outer seals will be doing all the work if the bearings are like this.

cheers

[meic]

Anybody who is thinking of replacing the bearings in their EBB shells might be tempted by these genuine FSA MR066 bearings at this price

http://www.chainreactioncycles.com/fsa- ... -prod87626

I thought I would buy 10 of them which may last me a lifetime, to my surprise even at that price they are pairs of bearings, so now I have 20 of them.

MR066 are (37x25x7) 6805 2RS bearings.

Note they are 7mm wide compared to the Shimano which I think are only 6mm wide.

Edit: typo in the dimensions

[Erudin]

Looks a good deal Meic, I think you have got a lifetimes supply there.

Gave the drivetrain on my Thorn Audax a good strip-down and clean today. The cheap Zen bearings I fitted in the Tiagra external bottom bracket on it over two years ago are still running smoothly.

Overall I find the advantages of external bb's and two-piece cranks compared to square taper outweigh the disadvantages.

[Rodwelljason]

I have just upgraded from a suntour xcm crank with s/t bottom bracket to shimano fc-t781 with hollowtech ii bearing. I wouldn't have noticed it had i not tried the better system but now its gone I can feel the abscence of flex compared with the old one. I put it down to...
How each crank arm interfaces together by the bearing has more points of contact and a design that just meshes together better. My old crank used chrome alloy cogs and the new one has much stiffer and lighter aluminium alloy. Plus much tigther tolerances with how the cogs engage the chain. The result has been amazing. I had upgraded all the rest of the groupset to xt but now every component is of the same level it just engages so much faster and all the gears work better. I can accelerate quicker because there is less drag from the bearing and more power is being translated to the wheels. I don't think its any one component that makes the difference. I think a combination of more flexible metals in cheap cogs. Connected to a bearing which can be prone to allow a certain amount of slip before it engages, compared to hollowtech, a slightly more flexible bearing...all put together it just males s/t feel sloppier, hallowtech feels stiffer, engages faster, using the crank meant for the groupset means the cassette changes are more precise. It has changes the feel of my bike as much as better wheels did. Well worth 150 quid.

[hamster]

So what you are actually saying is that a new high-end groupset works better than a worn out cheap one?

[rogerzilla]

More accurate chainline (irrelevant with a derailleur), possibly lighter weight, extra stiffness you won't notice, might be better for really huge riders who frequently cracked square taper cranks (we're talking tiny fractions of a per cent here).

Against that you have worse sealing, clunky looks and an inherently wider minimum chainline, which makes HT2 a bit useless for some non-derailleur setups, eben if ypu could find suitable cranks.

[Rodwelljason]

No the old crankset was in a reasonable state of repair. How a hallowtech crank fits together has more points of contact and is inherently stiffer than square taper. The setup is lighter and has less resistance in the bearing. But even the point about it just being a better crankset is a valid argument for them because most hallowtech cranksets are mid to high end, where square taper parts are generally older and lower quality so in an argument about square taper vs hallowtech...the fact you can only get that level of part on hallowtech is highly relevant to someone wanting to upgrade a square taper bb that wants high end parts. But completely ignore the fact that its a £150 crank compared to something more around £40. I put forwards that given two versions of the same crank. One square taper, one hallowtech. The hallowtech version would feel smoother and stiffer because of lower bearing resistance and tighter tollorence in the connection method between the crank arms.

[hamster]

I can accelerate quicker because there is less drag from the bearing and more power is being translated to the wheels. I don't think its any one component that makes the difference. I think a combination of more flexible metals in cheap cogs. Connected to a bearing which can be prone to allow a certain amount of slip before it engages, compared to hollowtech, a slightly more flexible bearing...all put together it just males s/t feel sloppier, hallowtech feels stiffer, engages faster, using the crank meant for the groupset means the cassette changes are more precise. It has changes the feel of my bike as much as better wheels did. Well worth 150 quid.

Most drivetrain losses are in the chain and derailleur, not the bottom bracket. Even those are only in the order of 2-3%. The rest is tyre drag and aerodynamics.

What is all this bearing slip and engagement you describe? It makes no sense to me for a description of the rotating shaft in a bottom bracket.

I suspect that you have never tried a decent square taper setup, e,g, Campag Record, Royce etc. or even Shimano M735 XT on a UN72.

The Shimano obsolescence machine made all the same claims about its previous two versions of Hollowtech: yet the bearings were undersized and had a pitifully short lifetime, while the crank interface had to be redesigned (Hollowtech 2) as it failed.

[thelawnet]

I can accelerate quicker because there is less drag from the bearing and more power is being translated to the wheels. I don't think its any one component that makes the difference. I think a combination of more flexible metals in cheap cogs. Connected to a bearing which can be prone to allow a certain amount of slip before it engages, compared to hollowtech, a slightly more flexible bearing...all put together it just males s/t feel sloppier, hallowtech feels stiffer, engages faster, using the crank meant for the groupset means the cassette changes are more precise. It has changes the feel of my bike as much as better wheels did. Well worth 150 quid.

Most drivetrain losses are in the chain and derailleur, not the bottom bracket. Even those are only in the order of 2-3%. The rest is tyre drag and aerodynamics.

What is all this bearing slip and engagement you describe? It makes no sense to me for a description of the rotating shaft in a bottom bracket.

I suspect that you have never tried a decent square taper setup, e,g, Campag Record, Royce etc. or even Shimano M735 XT on a UN72.

The Shimano obsolescence machine made all the same claims about its previous two versions of Hollowtech: yet the bearings were undersized and had a pitifully short lifetime, while the crank interface had to be redesigned (Hollowtech 2) as it failed.

As I understand it, the two previous versions in terms of the crank interface are called 'Octalink' . Hollowtech appears to refer to the crank arms being hollow

I have a 'Hollowtech' crankset with an Octalink BB, and another crankset with a Hollowtech II BB, however this second crankset is NOT Hollowtech I or II because the crank arms are solid.

This doesn't seem a hugely important consideration for most people, but it's what Shimano do...

There's not too much in common between Octalink (three piece) and Hollowtech II (two piece) crankset

[hamster]

You are right, I meant Octalink. At the same time they branded the cranks Hollowtech IIRC with a new forging of hollow cranks.