# Hollowtech bearings



## Crackle (24 May 2015)

Ok, I did know I might have trouble with them right from the off but I wasn't expecting grunching at 200 miles. It was a ride along the beach which did it. It looks and feels like sand got past the seals, which I've read is the main problem with hollowtech, that the seals don't, well, seal. Is there a better aftermarket hollowtech or a seal you can fit which is better?

They are cheap and easy to replace but not cheap if I have to do it every 200 miles.


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## Yellow Saddle (24 May 2015)

Hollowtech has many flaws, your problem is just one of them. I don't think sand got past the seals unless you perhaps pedaled underwater whilst sand was slushing around. The seal won't normally let sand past it. My guess is that you don't have mudguards and that the salty water sprayed up the back, dripped down inside the seatpost and then collected in the BB where the water slowly seeped into the bearings. My second guess is that you have no drainage hole in the BB shell of the frame.

Let me know if my crystal ball is malfunctioning or not.

Having said that, Hollowtech is a very poor design and a result of a legacy problem. If we can wipe the slate clean and redesign the bicycle we won't end up with hollowtech BB adapters at all.

One good thing about Hollowtech BBs is that the price came down quite a lot from the early days. Then it was worthwhile replacing the bearings but nowadays the entire adapter cup is cheaper than a quality bearing. Further, you can now buy them individually whereas previously it was the set or nothing.


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## Crackle (24 May 2015)

Yellow Saddle said:


> Hollowtech has many flaws, your problem is just one of them. I don't think sand got past the seals unless you perhaps pedaled underwater whilst sand was slushing around. The seal won't normally let sand past it. My guess is that you don't have mudguards and that the salty water sprayed up the back, dripped down inside the seatpost and then collected in the BB where the water slowly seeped into the bearings. My second guess is that you have no drainage hole in the BB shell of the frame.
> 
> .



Oooh I don't know how many points I can give you for that. I do have guards, I did cycle in sandy water, through the tide line actually and I'll have to check on the drainage hole. I took the cranks off and there was, naturally enough, sand everywhere. One bearing was refusing to move until I loosened it off and the other was OK, both feel stiffish now but I don't have a tool to remove the cups until next week and I haven't looked if I can pop the seal and get to the bearings anyhow?

Edit: but the rear guard is on the seatpost, so spray can still drip down.


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## Yellow Saddle (24 May 2015)

Crackle said:


> Oooh I don't know how many points I can give you for that. I do have guards, I did cycle in sandy water, through the tide line actually and I'll have to check on the drainage hole. I took the cranks off and there was, naturally enough, sand everywhere. One bearing was refusing to move until I loosened it off and the other was OK, both feel stiffish now but I don't have a tool to remove the cups until next week and I haven't looked if I can pop the seal and get to the bearings anyhow?


OK, that's quite a confession. I think the bearing is innocent in this instance. But I'll give you 5 marks for at least trying with the mudguard. Tell me, was it at least fun peddling through the surf and sand? If you remove the cups next week only, the bearings would have rusted beyond saving. Further, it is impossible to get the plastic seal off without cracking it. Lastly, the bearing in there is a 6805 - however, not a real 6805. It is 4mm wide instead of 6805's 5mm. You cannot buy a replacement bearing at all from normal bearing companies. You can get them from enduroforkseals.com (search Enduro bearings bicycle if that link doesn't work).


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## Crackle (24 May 2015)

Yellow Saddle said:


> Tell me, was it at least fun peddling through the surf and sand?


It was  However, it might be my last excursion along the beach if it's going to cost me a bearing every time. Next time I'll hire the fatbike from the lbs and wreck their bearings. And before you ask, they suggest a beach ride if you hire it.


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## Crackle (24 May 2015)

Oh and my original question still stands. I realize I've gone beyond normal operating conditions here but is there a better sealed Hollowtech than the Shimano cups, as it strikes me that any gritty water is going to get in and shorten the life considerably.


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## Yellow Saddle (24 May 2015)

Crackle said:


> Oh and my original question still stands. I realize I've gone beyond normal operating conditions here but is there a better sealed Hollowtech than the Shimano cups, as it strikes me that any gritty water is going to get in and shorten the life considerably.



No.


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## Cubist (24 May 2015)

Well, kind of better sealed (just) , but in any case more rebuildable. Gusset EX24. They have a removable tophat shaped bearing shield, However, given that you can generally get SLX/XT standard BBs for less than a tenner online if you shop around, there's a train of thought that wonders why you would bother. Gusset, apart from having a name that @Fnaar would get all sniffy about, also come in bling colours, don't cost the earth, and have the added advantage that you can remove the bearing seals with a pick, flush and regrease them. That's the problem with Shimano.. if you know you've got them wet you can't (easily) get into them to sort them out, although it isn't impossible, and you don't have to take them out of the frame to do it. 

There;'s always Hope to consider. You can pick them up for about £30 used, and again, are rebuildable, but more importantly regreasable.


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## Crackle (24 May 2015)

Yellow Saddle said:


> ? If you remove the cups next week only, the bearings would have rusted beyond saving



No, it was last Tuesday and I've done another ride since, during which the BB complained bitterly for a few miles but then freed up. So I think I may well have considerably shortened their life but they ain't dead yet.

Here's the offending ride:-
https://www.cyclechat.net/threads/your-ride-today.173254/post-3702485



Cubist said:


> Well, kind of better sealed (just) , but in any case more rebuildable. Gusset EX24. They have a removable tophat shaped bearing shield, However, given that you can generally get SLX/XT standard BBs for less than a tenner online if you shop around, there's a train of thought that wonders why you would bother. Gusset, apart from having a name that @Fnaar would get all sniffy about, also come in bling colours, don't cost the earth, and have the added advantage that you can remove the bearing seals with a pick, flush and regrease them. That's the problem with Shimano.. if you know you've got them wet you can't (easily) get into them to sort them out, although it isn't impossible, and you don't have to take them out of the frame to do it.
> 
> There;'s always Hope to consider. You can pick them up for about £30 used, and again, are rebuildable, but more importantly regreasable.



Flush your gusset, splendid: I'll look into them but you're right. Doing some reading around after I posted this leads me to wonder if it's worth it. I did read that adding some grease on the seal lip will help the waterproofness, that could be useful but I'm not desperate to add a couple of miles of beach to one of my rides so I may take my usual procastination route and do nothing followed by the easy option, replace. Or then again......


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## Venod (24 May 2015)

I replaced Shimano & Race Face cups at an alarmingly fast rate until I got fed up and fitted Hope cups, been on the bike for about 2 years now with no problems.


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## byegad (24 May 2015)

I thought 4500miles was piss poor!


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## Crackle (24 May 2015)

byegad said:


> I thought 4500miles was piss poor!


pffff, lend it to me for a few miles.


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## Yellow Saddle (24 May 2015)

Crackle said:


> No, it was last Tuesday and I've done another ride since, during which the BB complained bitterly for a few miles but then freed up. So I think I may well have considerably shortened their life but they ain't dead yet.
> 
> Here's the offending ride:-
> https://www.cyclechat.net/threads/your-ride-today.173254/post-3702485



Born to be wild, sounds gnarly but the BB clearly found it too offensive and wilted.

A note on my answer to your question about better seals. I said no. I could have added that you won't find better seals but you do find serviceable BBs such as those mentioned and Chris King. The nature of these seals is such that they cannot be waterproof but that's a long story for another day.

Where I lived there used to be a company that organized coastal tours and I had a few customers in my repair shop that participated in these tours. They would bring their bikes in afterwards and they'd be stripped to the last nut and bolt, all bearings replaced and frame washed out. It was good for business, so I don't want to discourage you from riding in the surf. It puts food on someone's table somewhere.


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## Crackle (24 May 2015)

Yellow Saddle said:


> Where I lived there used to be a company that organized coastal tours and I had a few customers in my repair shop that participated in these tours. They would bring their bikes in afterwards and they'd be stripped to the last nut and bolt, all bearings replaced and frame washed out. It was good for business, so I don't want to discourage you from riding in the surf. It puts food on someone's table somewhere.


Yes, well, now I've fully reflected on my seaside sojourn, I think I'll cross it off the list. Total ride time, 40 mins. Bike cleaning time, at least double that and I've still got a sandy chain which will need re-visiting. Fettle time for pedals and BB, another hour, shortened life of BB, all in all, I've changed my mind, it wasn't worth it and 35quid a day for a fatbike I just give back is sounding like a good deal.


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## mrbikerboy73 (25 May 2015)

We used to ride our BMX's through the sea as kids. Didn't do them much good but it was great fun!


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## I like Skol (27 May 2015)

I'm not sure that Hollowtech hasn't got a bad name for the wrong reasons. My hybrid came with the Shimano Deore Hollowtech set-up and I was unimpressed when the bearing got rough at only around 1,800 miles of commuting. I replaced these like for like as they were cheap and I refitted them exactly as the originals were fitted at the factory with the same size spacers (why wouldn't I?). These didn't last any longer and began to fail before the bike had covered 4,000 miles. I was now extremely disappointed and considered ripping out the hollow tech junk and going back to a chainset that would use a good old square taper UN55 BB that just lasts for almost ever. I decided to give it one more go and ordered the higher spec SLX/XT bearing cups. I suspect these are the same bearings and seals just fitted into a lighter housing but thought it might be worth trying to see if they would last any longer.
While fitting these new bearings I paid much more attention to the fitting process rather than just relying on the factory set-up. It was at this point that I noticed the flaw in the set-up. There was insufficient shims fitted either side of the bearings so that the removable L/H crank was bottoming out on the splines just before butting up to the bearings. This must have been allowing the bearings to run out of true as now I have slipped in an additional thin shim on the left side (I didn't want to move the chainrings away from the frame) the bearings have so far lasted around 8,000 miles.

Of course, none of this helps you Crackle, if you insist on soaking your bike in corrosive salty sea water then you only have yourself to blame!


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## djb1971 (27 May 2015)

You'd be amazed how little or how useless the grease is in some of the bb's. I always strip them down and fill with Mobil xhp222 grease, just pop the seals, fill, refit seal. This pushes grease through the rear seal. Do this a couple of times and the bearing will be done. They last me a long time.


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## Crackle (27 May 2015)

I like Skol said:


> Of course, none of this helps you Crackle, if you insist on soaking your bike in corrosive salty sea water then you only have yourself to blame!



Can I borrow your GT next time?



djb1971 said:


> You'd be amazed how little or how useless the grease is in some of the bb's. I always strip them down and fill with Mobil xhp222 grease, just pop the seals, fill, refit seal. This pushes grease through the rear seal. Do this a couple of times and the bearing will be done. They last me a long time.



I was thinking that there couldn't have been much grease in there to start.

Anyway my spanner has arrived, so I might remove the cups and see if I can pop the seals and have a look


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## djb1971 (27 May 2015)

Take your time popping the top hats out. I use a Stanley blade to lift the front up and slide the blade under as much as possible. Then use a finger nail to lift the inside of the lip and lift out with the blade. Do them when warm, the plastic is brittle when cold. Save any spare top hats from dead bb's as spares if you're heavy handed. Lift the seal of the front of the bearing with the sharp knife blade layer with grease pop seal back on, pop off and repeat. This pushes grease through the bearing. Then carefully pop the top hat back in


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## Yellow Saddle (27 May 2015)

I like Skol said:


> I'm not sure that Hollowtech hasn't got a bad name for the wrong reasons. My hybrid came with the Shimano Deore Hollowtech set-up and I was unimpressed when the bearing got rough at only around 1,800 miles of commuting. I replaced these like for like as they were cheap and I refitted them exactly as the originals were fitted at the factory with the same size spacers (why wouldn't I?). These didn't last any longer and began to fail before the bike had covered 4,000 miles. I was now extremely disappointed and considered ripping out the hollow tech junk and going back to a chainset that would use a good old square taper UN55 BB that just lasts for almost ever. I decided to give it one more go and ordered the higher spec SLX/XT bearing cups. I suspect these are the same bearings and seals just fitted into a lighter housing but thought it might be worth trying to see if they would last any longer.
> While fitting these new bearings I paid much more attention to the fitting process rather than just relying on the factory set-up. It was at this point that I noticed the flaw in the set-up. There was insufficient shims fitted either side of the bearings so that the removable L/H crank was bottoming out on the splines just before butting up to the bearings. This must have been allowing the bearings to run out of true as now I have slipped in an additional thin shim on the left side (I didn't want to move the chainrings away from the frame) the bearings have so far lasted around 8,000 miles.
> 
> Of course, none of this helps you Crackle, if you insist on soaking your bike in corrosive salty sea water then you only have yourself to blame!



If there were insufficient shims fitted either side, then you would have had some end float (which can be taken up by the funny-shaped plastic gadget that screws into the axle). However, end- float does not damage the bearings. It just causes the odd clunk from time to time.

It isn't as easy as just fitting shims both sides. There is a formula according to which these are fitted.

On English thread (BSA) threaded bicycles, the BB shell comes in two widths - 68mm and 73mm. The difference is 5mm. New BBs are supplied with three 2.5mm shims to make up the difference. If you have an e-type FD on your bike, it already acts as one 2.5mm shim and should that then be fitted onto a 68mm BB shell, you only need to fit one more 2.5mm spacer on the left to make up the missing 5mm. If you don't have an e-type FD, you then add the shim on the right and one on the left, giving you 5mm in total. If you have a 73mm BB on your bike and an e-type FD, you add nothing. If you have a standard FD, you add one shim.

The idea is that the crank spindle is 2.5mm too long for the widest style BB and you have to shim up the BB adapters to make up the missing space based on the shell width and the type of FD o the bike. Even then, BB shell widths are not precise, so the preload adjuster cap is used to snug the cranks up to the bearings.

SRAM uses a wavy spring washer to make up for the differences.

With too many shims in there you end up with not enough grip between the crank and the spindle and the crank comes off.


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## Yellow Saddle (27 May 2015)

djb1971 said:


> Take your time popping the top hats out. I use a Stanley blade to lift the front up and slide the blade under as much as possible. Then use a finger nail to lift the inside of the lip and lift out with the blade. Do them when warm, the plastic is brittle when cold. Save any spare top hats from dead bb's as spares if you're heavy handed. Lift the seal of the front of the bearing with the sharp knife blade layer with grease pop seal back on, pop off and repeat. This pushes grease through the bearing. Then carefully pop the top hat back in


 You are pretty dexterous. It is one precarious procedure that. Shimano did it's utmost to make it impossible.


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## I like Skol (27 May 2015)

Crackle said:


> Can I borrow your GT next time?


You wouldn't be able to handle a real bike 


Crackle said:


> Anyway my spanner has arrived, so I might remove the cups and see if I can pop the seals and have a look


From what I can remember (and it was 8,000 miles ago) there is nothing to see when you remove the cups. Curiosity has got the better of me so of I trot to route in the parts bin....

Now don't ask me why I have 2 x knackered hollowtech BB's in my spares cache? 






As can be seen, nowhere to insert grease and the top hat doesn't appear to want to come out without force which I suspect may render it unserviceable!


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## Crackle (27 May 2015)

djb1971 said:


> Take your time popping the top hats out. I use a Stanley blade to lift the front up and slide the blade under as much as possible. Then use a finger nail to lift the inside of the lip and lift out with the blade. Do them when warm, the plastic is brittle when cold. Save any spare top hats from dead bb's as spares if you're heavy handed. Lift the seal of the front of the bearing with the sharp knife blade layer with grease pop seal back on, pop off and repeat. This pushes grease through the bearing. Then carefully pop the top hat back in


I found one youtube vid which showed me the basics but not the finesse.



I shall carefully prise at things but back off if I lack the skill until I have a spare standing by.


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## I like Skol (27 May 2015)

Yellow Saddle said:


> If there were insufficient shims fitted either side, then you would have had some end float (which can be taken up by the funny-shaped plastic gadget that screws into the axle).


You didn't read what I said or think about what your reply says, did you?


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## djb1971 (27 May 2015)

Once you lift from under the front, the top hat does come out reasonably easily. 

Practice on the knackered ones


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## Yellow Saddle (27 May 2015)

I like Skol said:


> You didn't read what I said or think about what your reply says, did you?


I am not sure which part is so offensive? I disagreed that you can make the bearings run out of true by removing/not having enough shims and then I explained how the number of shims are calculated. Where did I go wrong?


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## I like Skol (27 May 2015)

I like Skol said:


> There was insufficient shims fitted either side of the bearings so that the removable L/H crank was bottoming out on the splines just before butting up to the bearings.





Yellow Saddle said:


> If there were insufficient shims fitted either side, then you would have had some end float (which can be taken up by the funny-shaped plastic gadget that screws into the axle).





Yellow Saddle said:


> I am not sure which part is so offensive? I disagreed that you can make the bearings run out of true by removing/not having enough shims and then I explained how the number of shims are calculated. Where did I go wrong?


Offensive? I'm just amused that you are suggesting I could pull the L/H removable crank onto the un-splined section of the axle/spindle with the plastic preload screw to make up for the lack of sufficient spacers. The arm had bottomed on the splines and no amount of torque on the preload adjuster was going to remove the endfloat!


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## Yellow Saddle (27 May 2015)

I like Skol said:


> Offensive? I'm just amused that you are suggesting I could pull the L/H removable crank onto the un-splined section of the axle/spindle with the plastic preload screw to make up for the lack of sufficient spacers. The arm had bottomed on the splines and no amount of torque on the preload adjuster was going to remove the endfloat!


But I didn't suggest that. I only said that the preload screw makes up for inaccuracies in BB shell width. Nevermind...


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## I like Skol (27 May 2015)

Yellow Saddle said:


> If there were insufficient shims fitted either side, then you would have had some end float (which can be taken up by the funny-shaped plastic gadget that screws into the axle).





Yellow Saddle said:


> But I didn't suggest that. I only said that the preload screw makes up for inaccuracies in BB shell width. Nevermind...


I'm sure I have not misinterpreted what your post stated. Whether that is what you meant to say is another matter.


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## potsy (27 May 2015)

I've had a couple of these type of bearings go over the last few years, never thought to try and service them just bought replacements.
If I have an old one I will have a practice at removing the seal.


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## I like Skol (27 May 2015)

I have often thought that I should send some of my old bearings to THESE GUYS as they offer to fit bigger, better bearings. I remember now, that is why I have kept the old ones.

EDIT: with hyperlink this time


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## Yellow Saddle (27 May 2015)

I like Skol said:


> I have often thought that I should send some of my old bearings to THESE GUYS as they offer to fit bigger, better bearings. I remember now, that is why I have kept the old ones.
> 
> EDIT: with hyperlink this time



I have been using them for years and have probably purchased 1 000 Enduro BB bearings in about 5 years. Nowadays the Shimano product is so cheap that it isn't worthwhile doing the procedure. Further, it only works in some Shimano BBs, the one pictured on the second page of this thread won't work. It needs a thin aluminium ridge around (i.e. al larger bearing, effectively a modified 6805).

They are not better though and certainly not bigger. They still have to fit in the same space as the old ones so they can't be bigger.

The design of the system is flawed. The hollow crank spindle flexes on the left hand side (that side being the only one that transmits torque down the axle) and pushes the bearing out of alignment, causing a crash inside the grooves with the balls.

The seal on the Enduro unit is also flawed. It is only a lip seal and a single seal cannot separate two liquids.


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## I like Skol (10 Jun 2015)

I like Skol said:


> the bearings have so far lasted around 8,000 miles.
> 
> Of course, none of this helps you Crackle, if you insist on soaking your bike in corrosive salty sea water then you only have yourself to blame!


Damn you Crackle!
My bike was making a random clicking noise on the commute yesterday and I didn't really pay it much attention. However, it was still doing it today, and a little bit worse so I did pay attention this time and it was happening only when pedalling. Once home I popped the chain off and spun the cranks, sure enough a rumbling could be heard through the frame and there is detectable play, mainly at the left, non-driveside bearing. 

I reckon spraying the garden hose around to remove the sand after the Llandudno ride probably did for it, I knew I shouldn't have cleaned it!


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## Crackle (11 Jun 2015)

That's your own fault for being smug, you woke the Hollowtech demons. This reminds me that I haven't touched mine yet.


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## Crackle (2 Mar 2016)

I still haven't touched mine. Well; I took it apart, decided not to fiddle with the seals, stuck it back together, rode it until it stopped grunching and it's still going. Occasionally it stiffens a little and after a few miles, frees up. It still feels smooth, no play, so I'm not entirely sure what's going on or whether to finally replace it. I think while I'm still doing short or local rides I'll leave it but if my plan for a longer adventure matures I may replace it before I go: Stupid design.


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## ozboz (27 Mar 2016)

Mmm , I fitted HT on my mountain bike , got me thinking now ,,may whip it off while im waiting for wheel build , just t be on safe side , prob a good time to service idrive to ,


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## Blue Hills (27 Mar 2016)

Still p'ed off about not being advised of this much discussed weakness when I bought my Hewitt. Not being too technical I never gave the BB much thought when speccing the bike. I can see the bike being switched to square taper in the future (or if that is problematical for Shimano of course discontinued the square taper chainset that would be my preferred choice) Octalink. The bike was bought for extended loaded touring - what the F do I care about supposedly small increases in stiffness or small decreases in weight?


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## ozboz (27 Mar 2016)

I put HT on my MTB about three years ago SLX tripple , after reading posts on here , I decided to strip the whole drive chain off , this bike of mine has been through a lot of everything , submerged and ridden many times in the Thames washouts around Richmond ,mud up to my ear 'oles , the photo shows the Idrive components , as you can see , well used and full of gunk , The bearings in the HT appear to be as good as the day I put in on , seals in tact , no friction noise or play , so all in all good kit in my book !


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## Pale Rider (27 Mar 2016)

I'm also baffled by the hiding Hollowtech is taking on here.

My Cannondale MTB hasn't had enough use to form an opinion, but my mate Chris the mechanic reckons Hollowtech is decent kit.

He's rarely wrong on such matters, but it does appear user experiences of Hollowtech vary a lot.


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## Yellow Saddle (27 Mar 2016)

ozboz said:


> View attachment 122936
> I put HT on my MTB about three years ago SLX tripple , after reading posts on here , I decided to strip the whole drive chain off , this bike of mine has been through a lot of everything , submerged and ridden many times in the Thames washouts around Richmond , the photo shows the Idrive components , as you can see , well used and full of gunk , The bearings in the HT appear to be as good as the day I put in on , seals in tact , no friction noise or play , so all in all good kit in my book !



See that black gunk on the adapter cup threads? That's aluminium rouge in what used to be clear green Shimano grease, a sure sign that the adapter cup is moving and fretting inside it's mount inside that iDrive adapter. That's the source of that irritating click click as you pedal which most iDrive owners cannot hear but which annoys everyone else in the squad.

Now, when you put the whole lot back, leave the chain off for a minute and spin the crank whilst putting your ear against one of the major tubes on the bike. That will act as a stethoscope and tell you exactly what state the bearings are in. A good bearing is silent, a bad bearing rumbles and a BB30 bearing roars. When you spin that crank with your ear against the tube, make sure your teeth are not in the pedal's way.


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## ozboz (27 Mar 2016)

Dont know about shimano grease , I fitted the Idrive the same time as the HT , I used castrol ,but will try what you said ,i do not know which part you are identifying ,the bearings run on steel shims , I remember having problems fitting them as new , but any advice is well taken , Cheers , ive put them in soak to de gunk , when they are clean ill put another pic up , maybe a bit clearer incase there is a prob , this a '97 bike , parts , esp bearings are not easy come by


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## Yellow Saddle (27 Mar 2016)

ozboz said:


> Dont know about shimano grease , I fitted the Idrive the same time as the HT , I used castrol ,but will try what you said ,i do not know which part you are identifying ,the bearings run on steel shims , I remember having problems fitting them as new , but any advice is well taken , Cheers , ive put them in soak to de gunk , when they are clean ill put another pic up , maybe a bit clearer incase there is a prob , this a '97 bike , parts , esp bearings are not easy come by



I'm referring to the BB itself, which comprises the two bearing assemblies (called adapter cups by Shimano) and a plastic sleeve connecting left to right. The very bottom item in your photo. If you look at the screw thread on both cups, you'll notice it is black. That black is aluminium particles fretted off the cups and bike and suspended in the grease that was on the thread, supplied by Shimano on new cups. This grease is a beautiful translucent green before fitting. After a few hundred miles it turns black, even if the bike stays dry. This indicates that the cups move inside the BB shell. That's also the source of the familiar click click 9with every pedal stroke) that emanates for hollowech BBs.

However, as I said with my tongue firmly in my cheek, iDrive owners cannot hear that click because all those fancy iDrive parts have a cacophony of their own. Yours almost certainly would not have been silent.


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## ozboz (27 Mar 2016)

The black on the threads , how would these things move ? If they were loose surely it would be noticed whilst riding ? The idrive shell is made of some form of alloy , could the aluminium be have some reaction with the metal of the idrive , the only noise I got from the idrive , which was s click happened when the dogbone worked itself loose , anyway , to be fair , there shouldnt be anything on the threads bar the grease that was applied at the time of fitting , i may try some PTFE tape when I refit them , give em a while and then check them out


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## Yellow Saddle (28 Mar 2016)

ozboz said:


> The black on the threads , how would these things move ? If they were loose surely it would be noticed whilst riding ? The idrive shell is made of some form of alloy , could the aluminium be have some reaction with the metal of the idrive , the only noise I got from the idrive , which was s click happened when the dogbone worked itself loose , anyway , to be fair , there shouldnt be anything on the threads bar the grease that was applied at the time of fitting , i may try some PTFE tape when I refit them , give em a while and then check them out


They move through two mechanisms:
1) Precession. Because the crank is a very uneven power source it places large unbalanced loads on the BB shell. Imagine for a minute that the BB shell (that's the bicycle part of the BB) is made of rubber. You can then visualize how the shell ovalises in the direction where the crank points as the crank pulls the centre of the circle around 360 degrees. Although the shell is not made from rubber, metal is nevertheless elastic and that actually happens, sans the exaggeration I forced to demonstrate the point. This is the force that causes the one side to spontaneously unscrew if it wasn't a reverse or left hand thread.
2) Dynamic joint. A dynamic joint is something that can move because it is literally not welded. Take a bolt and nut and play with it. Notice how the nut can move against the bolt even though it is screwed halfway in. Now, if you back that nut up against the workpiece, it appears as if the nut cannot wobble on its axis anymore but that's an illusion. If the workpiece moves, the nut wobbles with it. A screw of the type you see on your BB is exactly the same. Although it backs up against a flange, it can never be perfectly stable. With pedaling, it moves. And when it moves under pressure such as when you torque it up, the two parts fret against each other and metal particles break loose. That's the black rouge you see in your grease.

The external BB is poorly designed to counter these two forces described above. Because it comprises two shallow cups on the same axle (crank), they can move independently and don't support each other. An internal BB does. Further, think of a car wheelnut with its tapered flange. That design is perfectly stable and doesn't move. We know that because you don't need reverse threads on the one side. Had he BB cups been designed with tapered shoulders we would not have had the problem. Further, if the bearings inside were like car wheel bearings, angular contact bearings, the bearings would have lasted longer.

Hollowtech is not perfect but it is OK in screw-in versions. With press fit it is a disaster. Screw-ins can be removed and "serviced" (i.e. thread cleaned and regreased). Pressfit can't. Also, Shimano has started to sell single cups. This means you can buy left ones separately and replace only those when they fail. If you buy in bulk for a workshop, you'll know that the fail ratio is about three to one. Our workshop used to buy then separately (many won't because there's more money to be made by denying that they are available separately) and our ratio was three (left) to one (right) without fail. That doesn't mean everyone's personal ration will be three to one, that was the average over a large sample.

PTFE tape silences it for a while but that eventually wears off. The best treatment is regular removal and cleaning and refitting with copper compound instead of grease.


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## Pale Rider (28 Mar 2016)

Yellow Saddle said:


> Hollowtech is not perfect but it is OK in screw-in versions. With press fit it is a disaster. Screw-ins can be removed and "serviced" (i.e. thread cleaned and regreased).



That's more or less what my mate Chris the mechanic said.

A replacement Hollowtech BB for my Cannondale is about a tenner.

That's no good if the bracket won't do the job, but provided it gives a reasonable amount of service, the occasional £10 replacement is neither here nor there - I would view it in the same light as a chain.

http://www.wiggle.co.uk/shimano-deo...|pcrid|71714705102|pkw||pmt||prd|5360701407uk


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## ozboz (28 Mar 2016)

Well , 
that is very useful info for all ! .
it is a very simple ( as you know ) to remove these and service , which I will , If I rode the bike a lot more then I would maybe replace it with a square taper , I do check the idrive regularly , and it is , as you see well packed with grease , i do use Comma copper grease on some of the parts in there as it happens , 
Thanks for taking the time to explain this , Cheers !!


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## Crackle (28 Mar 2016)

What's an idrive. I did Google it but couldn't quite work it out from the results I got?


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## psmiffy (28 Mar 2016)

Crackle said:


> What's an idrive. I did Google it but couldn't quite work it out from the results I got?



You need to update your googling skills



> I-Drive suspension design, referred to as 'Independent Drivetrain' on newer models, uses a ''floating'' bottom bracket unit that allows for a relatively high main pivot location without the main drawback that is usually associated with it - excessive chain growth. The high pivot helps the bike absorb hard, direct impacts due to the rearward axle path that it affords, but it's the floating bottom bracket that lets such a design work without the massive chain growth that would usually be associated with such a design. It does this by letting the bottom bracket move in roughly the same plane as the rear axle by locating it on a separate element that pivots off of the swingarm, all while being attached to the front triangle by a short link, essentially creating a four-bar linkage system even if it doesn't resemble what comes to mind when you hear that term.


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## Crackle (28 Mar 2016)

psmiffy said:


> You need to update your googling skills


Can you conjure me a picture as well Smiffy?


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## psmiffy (28 Mar 2016)




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## psmiffy (28 Mar 2016)




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## potsy (28 Mar 2016)

Sounds like more marketing claptrap to me


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## Crackle (28 Mar 2016)

Ah I get it now. I would have thought you lose a lot more pedalling efficiency with such a mechanism, than you do with normal rear suspension.


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## Blue Hills (28 Mar 2016)

Pale Rider said:


> That's no good if the bracket won't do the job, but provided it gives a reasonable amount of service, the occasional £10 replacement is neither here nor there - I would view it in the same light as a chain.
> 
> http://www.wiggle.co.uk/shimano-deo...|pcrid|71714705102|pkw||pmt||prd|5360701407uk



I do hope you aren't saying it is reasonable to replace/even service by tinkering (doing the mznufacturers job for them) a bottom bracket as frequently as a chain.

And as far as i am concerned a proper bottom bracket shouldn't need to be replaced "occasionally" - i would say "very rarely".

Maybe i have misinterpreted what you wrote but i do hope you haven't fallen for the marketeers' campaign to lower expectations.


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## ozboz (30 Mar 2016)

This the style of idrive on my GT MTB


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## Yellow Saddle (31 Mar 2016)

ozboz said:


> View attachment 123300
> This the style of idrive on my GT MTB


My sincere condolences.


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## Motozulu (31 Mar 2016)

Shimano Hollowtech BB on the Chief - 2 years and 2 months old and still going strong and smooth - what's the problem?


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## Yellow Saddle (31 Mar 2016)

Motozulu said:


> Shimano Hollowtech BB on the Chief - 2 years and 2 months old and still going strong and smooth - what's the problem?


My Aunt Mabel has a bicycle that's been in her shed for 40 years and 8 months and 13 days still has the same BB and chain and tyres. She uses the bicycle to go to church on each and every leap year Sunday if it doesn't rain on that day. Her BB is still in perfect nick too. Strange, these things.


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## ozboz (31 Mar 2016)

Yellow Saddle said:


> My sincere condolences.



Condolences ?
No need for them !
perfectly good , this bike is from 1997 , goes everywhere any other MTB does , yep Ive taken on board what was said about HT bb , but to be fair , I went to Evans looking for a chainset , I was informed that HT was the buisness ,so I went with it , and to be fair to Shimano with this SLX tripple HT Ive had no problem , after 3 years maybe , riding in through deep water, caked in mud,slime , dustbowls , apart from the black residue on the threads that you identified , and the dogbone becoming loose within the idrive , no problem with any of it really , a lot of hard riding has developed a prob with the frame ,but rather than repeat all , I put a thread up in the MTB forum


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## Motozulu (31 Mar 2016)

Yellow Saddle said:


> My Aunt Mabel has a bicycle that's been in her shed for 40 years and 8 months and 13 days still has the same BB and chain and tyres. She uses the bicycle to go to church on each and every leap year Sunday if it doesn't rain on that day. Her BB is still in perfect nick too. Strange, these things.



Aaah right, that must be it then. Obviously the Snowdon, Peaks, Lakes, BPW, Degla, Swinley, Pines, Afan, Penmachno, CYB etc trips it's done are about the same then.
Good job everyone loves a smartarse, eh?


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## OskarTennisChampion (2 Apr 2016)

psmiffy said:


>



I'm surprised you can stay upright while pedalling,with Conti Baron's on.


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