Another Axle "Standard" - really? Why? - Now Called "Boost" by SRAM

[MARKL]

Yeah there is one other factor. Bonding.

For carbon frames an alloy BB must be bonded into the frame in no high stress area. This has shown quite a few failures in the past which is a complete frame warranty (getting cracks around the BSA insert). So manufacturers (in addition to your points above) have moved towards pressfit . Generally, they won't warrant a frame for a creak so for the manufacturer, the possible failure is a no cost to them compared to bonding a shell in, which is now their problem.

Anyways, they shouldn't creak, and of they do, they should be fixable, but mechanics and owners either do t know how or won't (eg strong hold locktite or epoxy)

and the fact that no bike manufacture dares to tap threads into a carbon frame? for very good reasons. So if a manufacturer really wanted a threaded bb they go for the heavier option of inserting metal threads but as pharma pointed out is inferior straight away to press fit.

The biggest advantage Pharma pointed out is manufacturers won't warrant your frame when it creaks...winning! Unless you like a frame that creaks, then awesome :frusty: They are a shit standard, especially press fit.

Try some reading...http://www.pinkbike.com/news/to-the-point-bottom-brackets-2014.html

http://www.bikeradar.com/au/gear/article/complete-guide-to-bottom-brackets-36660/

 

[The Duckmeister]

and the fact that no bike manufacture dares to tap threads into a carbon frame? for very good reasons. So if a manufacturer really wanted a threaded bb they go for the heavier option of inserting metal threads but as pharma pointed out is inferior straight away to press fit.

There's a simple reason why threads are not cut directly into carbon shells. Strong though the stuff is under tension, carbon composite laminates are comparitively soft and do not have the shear strength to handle the wracking loads imposed through the crank assembly.

Quite frankly press-fit is only marginally better than threading into carbon. That softness of the material makes it prone to wear from bits that are just shoved in with no mechanical fastening & subjected to the same wracking loads. If the tolerances are not precise to within a fraction of a poofteenth of a micron, bits will move & chew out the carbon, then your BB will simply fall out. Trek roadies are a prime example of this.

A threaded metal insert (or a short one on each side for the weight-conscious) is a far superior option.... if it's titanium rather than aluminium. Aluminium is used because it's cheap, even the harder alloys such as 7050 or 7075 that are used for such a purpose, and easy to work. Its problems outweigh its benefits though.... The stuff oxidises at the drop of a hat, and that oxide reduces the ability for the glue (which is not heavy) to stick because the surface is literally falling apart. Next, aluminium is not thermally stable; it has a higher expansion/contraction rate that carbon as temperature changes, which stresses the bond, especially in cold conditions, where it tries to shrink away from the carbon. Finally, aluminium & carbon are virtually at opposite ends of the galvanic scale. If the aluminium is not completely isolated from direct contact with the carbon component of the composite, it will corrode away.

Titanium on the other hand addresses these problems - it is resistant to oxidation, so it's less sensitive to surface prep. It's very close to carbon on the galvanic scale, so electrolytic corrosin is virtually non-existent, and its greater density (yes, that does mean it's heavier for an equally-sized chunk than aluminium, but its vastly superior strength:weight means less needs to be used for the same or better effect) improves its thermal stability. The downside is that it's expensive, partially in bare material cost, but more due to the fact that it's very difficult to work.

 

[billymtb]

The biggest advantage Pharma pointed out is manufacturers won't warrant your frame when it creaks...winning! Unless you like a frame that creaks, then awesome :frusty: They are a shit standard, especially press fit.

Try some reading...http://www.pinkbike.com/news/to-the-point-bottom-brackets-2014.html

http://www.bikeradar.com/au/gear/article/complete-guide-to-bottom-brackets-36660/

In your opinion should carbon frames be tapped directly or have metal cup inserts?

There's a simple reason why threads are not cut directly into carbon shells. Strong though the stuff is under tension, carbon composite laminates are comparitively soft and do not have the shear strength to handle the wracking loads imposed through the crank assembly.

Quite frankly press-fit is only marginally better than threading into carbon. That softness of the material makes it prone to wear from bits that are just shoved in with no mechanical fastening & subjected to the same wracking loads. If the tolerances are not precise to within a fraction of a poofteenth of a micron, bits will move & chew out the carbon, then your BB will simply fall out. Trek roadies are a prime example of this.

A threaded metal insert (or a short one on each side for the weight-conscious) is a far superior option.... if it's titanium rather than aluminium. Aluminium is used because it's cheap, even the harder alloys such as 7050 or 7075 that are used for such a purpose, and easy to work. Its problems outweigh its benefits though.... The stuff oxidises at the drop of a hat, and that oxide reduces the ability for the glue (which is not heavy) to stick because the surface is literally falling apart. Next, aluminium is not thermally stable; it has a higher expansion/contraction rate that carbon as temperature changes, which stresses the bond, especially in cold conditions, where it tries to shrink away from the carbon. Finally, aluminium & carbon are virtually at opposite ends of the galvanic scale. If the aluminium is not completely isolated from direct contact with the carbon component of the composite, it will corrode away.

Titanium on the other hand addresses these problems - it is resistant to oxidation, so it's less sensitive to surface prep. It's very close to carbon on the galvanic scale, so electrolytic corrosin is virtually non-existent, and its greater density (yes, that does mean it's heavier for an equally-sized chunk than aluminium, but its vastly superior strength:weight means less needs to be used for the same or better effect) improves its thermal stability. The downside is that it's expensive, partially in bare material cost, but more due to the fact that it's very difficult to work.

Woah, I honestly learnt alot from this post. How tight are these tolerances? Are they so tight that ti cups are nearly cheaper than trying to achieve these tolerances?

 

[moorey]

A couple of weeks ago, old mate rode his giant xtc composite. On a 30 km loop, pressfit BB cup popped out 6 times. Are lumps of deadwood the precise tools they recommend for installation?

 

[Ackland]

A couple of weeks ago, old mate rode his giant xtc composite. On a 30 km loop, pressfit BB cup popped out 6 times. Are lumps of deadwood the precise tools they recommend for installation?

Could try proper crank installation? :noidea:

Not seeing how there was enough play for the cups to pop out

 

[pharmaboy]

Wheels manufacturing BBs. Anodized so don't oxidise, locktite the shell in and press in replacement bearings each time - when it's worn out, heat it up and remove the shell, buy new one from ebay

Of course it's not really neccessary, if the BB was made the right size, it should fit neat anyway - suspect the problem is less these days as manufacturers have learnt this

 

[JTmofo]

Hopes new PF has press in cups but (with a special tool) has a threaded inset to "lock" both cups through the bb. Mate is waiting on his to be delivered, fitting next week so can give an update on how it goes.

 

[merc-blue]

Hopes new PF has press in cups but (with a special tool) has a threaded inset to "lock" both cups through the bb. Mate is waiting on his to be delivered, fitting next week so can give an update on how it goes.

Praxis works have been doing this for sometime and they are probably the best BB available if your frame can take them.

 

[The Duckmeister]

On the subject of Press-fits, why the fuck do some manufacturers use a 41mm diameter shell, while others are 42mm? Riduculous.

 

[JTmofo]

Praxis works have been doing this for sometime and they are probably the best BB available if your frame can take them.

True, but the Hope BB is BB92 41mm compatible which is what my mate needed, Praxis wont fit the majority of frames.

 

[pharmaboy]

On the subject of Press-fits, why the fuck do some manufacturers use a 41mm diameter shell, while others are 42mm? Riduculous.

Heh? Bb30 is 42, 41 is std pressfit for shimano or GPX

 

[Ivan]

Now I'm confused.

 

[The Duckmeister]

Heh? Bb30 is 42, 41 is std pressfit for shimano or GPX

Nope, BB30 is 46mm (x68mm wide). BB90/92 (there's another mindfuck, why have two shell widths for the same fucking thing?) pressfits are 41 & 42mm depending on frame manufacturers' states of mind. A quick poke in Shimano's shopping list (which does not include any BB30 models) lists BB91 (XTR press-fit) in 41 & 42mm versions.

 

[MARKL]

In your opinion should carbon frames be tapped directly or have metal cup inserts?




Woah, I honestly learnt alot from this post. How tight are these tolerances? Are they so tight that ti cups are nearly cheaper than trying to achieve these tolerances?

Threaded metal insert is my personnel choice

Santa Cruz are still happy using them and clearly they could use whatever they like. I think the theoretical advantages of press fits are smaller than the real world disadvantages.

+1 great post from the Duck

 

[pharmaboy]

Nope, BB30 is 46mm (x68mm wide). BB90/92 (there's another mindfuck, why have two shell widths for the same fucking thing?) pressfits are 41 & 42mm depending on frame manufacturers' states of mind. A quick poke in Shimano's shopping list (which does not include any BB30 models) lists BB91 (XTR press-fit) in 41 & 42mm versions.

Soz, ducky, but its PF30 that is 46mm, and BB30 is 42mm. Don't know what the 42 version of bb91 is for - perhaps to try and fit cervelo so effort at their own std . I don't do road kids so completely ignore such bullshit. Don't know what all the step down/ setup IDs are so maybe it's one of those as well

http://problemsolversbike.com/files/tech/Bottom_Bracket_Standards_Reference.pdf

Edit additional info . Specialized OSBB has the 42mm pressfit shimano one

 

[JTmofo]

Soz, ducky, but its PF30 that is 46mm, and BB30 is 42mm. Don't know what the 42 version of bb91 is for - perhaps to try and fit cervelo so effort at their own std . I don't do road kids so completely ignore such bullshit. Don't know what all the step down/ setup IDs are so maybe it's one of those as well

http://problemsolversbike.com/files/tech/Bottom_Bracket_Standards_Reference.pdf

Good link for those who are confused. Hard to explain the standards without visual reference.

 

[Isildur]

OP updated with the launch of "Boost" by SRAM:

http://flowmountainbike.com/post-all/sram-backs-new-boost-148-standards/

 

[Calvin27]

Sram has some balls to challenge the market like that even with their hand in trek's butt.

1. They are trying to get frame manufacturers to adopt the new 148+ which can play out a few ways. They will have to flood the market with their oem stuff and drive this hard. With the dedicated hub products, they will definitely chase the high performance range of the market (upgrades) so there will be limited release to reduce risk that this becomes another od2. This means sram single handedly must provide all the oem stuff for this new standard as they are in the only position to do so cost effectively. This is after tried to force xd hubs onto the world which brings an interesting point - whether they will keep xd hubs when they have a little more space at the rear.

2. At the same time they are also challenging the front hub. 15x110 is probably a little easier for them to push onto consumers seeing they have the fork market pretty much cornered. It is a risk though, if they push it too hard they will loose market share to fox and maybe even give some more power to xfusion and the growing suntour. Fox is already the alternative to rockshox, xfusion is increasing their popularity and suntour are increasing their presence from the low end towards the mid range of the market - maybe this will be where we start seeing more Epinions that are the same price as xc32's (i suspect the value for money xc30 gold was to fend off this threat).

So I'm guessing sram doesn't really give a crap about the 148 hub, it's probably some sort of negotiation with trek to make sure they spec 110mm forks. For them the hub market is not where they can compete (or want to) except for oem so it makes no sense to introduce new standards other than to cause pain for you, me and probably a few component manufacturers (might be a legit strategy to put them out of business though). I think it's the front fork they really want. I'd guess they have close to maximum market share with their mass popular xc30 gold, reba, and pikes forks. Rather than wait for fox and co to catch up, it looks like they are trying to run from their competition. It doesn't matter if 148 fails for them, but it does for trek (this ain't not od2 simple fix with a new bearing!).

 

[SummitFever]

A 110mm wide front hub! Why does that sound familiar...

I wonder what width my 20mm thru axle hubs are?

To further add to the stupidity, these boost 110mm hubs do not result in a zero dish front wheel, or a reduction in dish. No, the geniuses behind this have added 5mm flange width to both sides.

 

[Honzo15]

Why do we even have to call it "Standard"? Its not a standard, its just another option. I dont understand why people are getting so annoyed by these things, having options is a good thing and no one is forced to adapt to anything. The manufactures will make their own decisions and rightly so. If it brings real value (like the more options with wheel sizes) its only good for us.