Fitting BB30 chainset, help!

papajimbo

I've just got a Sram red BB30 chainset for a Caad9 BB30 frame (currently with adapter for standard bottom bracket) so need to buy the bearings to fit it with. Looking around online it would appear that I can either get a set of bearings - two rings but no bottom bracket as such, or pressfit bottom bracket cups with bearings?! Am I completely misunderstanding the system? Is one better than the other? Are they the same thing but the images are different on different sites? Which should I get and why? And no, I'm not going to do the job myself, I'm daft but not that daft.

Pokerface

I'm somewhat in the same boat myself having a BB30 chainset on order for a dedicated BB30 frame.

I got the impression that the 'bearings' with the cups were adapters - so that you can use your BB30 chainset in a regular frame (or use a regular chainset in a BB30 frame).

My understanding is that if using a BB30 chainset in a BB30 frame, you just use the press-fit bearings.

Can you provide a link to the cups you are talking about?

papajimbo

You may be right, this is the link:

http://www.tredz.co.uk/productlist.aspx ... ts&f5=BB30


They're all over the place, cheapest from the ebay retailers. Let me know what you think.

Monty Dog

BB30 uses press-fit bearings. You can't use BB30 cranks on a regular 68mm bottom bracket shell as they simply aren't designed to fit - the BB30 shell is oversize and 68mm wide - designed for the bearings to fit internally - there simply isn't enough room between the 30mm spindle and a regular BB shell to fit the bearings. You can however get an adapter to allow you to use a conventional chainset or external bearing BB in a BB30 frame - confusing, eh?

sungod

^^^this

the sram bearings for bb30 are...



...or the much pricier ceramic...



they push into the bb30 shell (typically using a headset press plus adaptors)

the actual crankset will be either bb30 or bb30 i-a

the i-a stands for integrated adjuster, this is the preload adjuster on the non-driveside of the spindle, you can see it in this image...



if there's no adjuster then instead you set the preload by varying the number of plastic washers (by trial and error)

andi1363

Monty Dog wrote:

BB30 uses press-fit bearings. You can't use BB30 cranks on a regular 68mm bottom bracket shell as they simply aren't designed to fit - the BB30 shell is oversize and 68mm wide - designed for the bearings to fit internally - there simply isn't enough room between the 30mm spindle and a regular BB shell to fit the bearings. You can however get an adapter to allow you to use a conventional chainset or external bearing BB in a BB30 frame - confusing, eh?

You guys should check things out before giving advice :roll:

"We at SRAM saw the opportunity to make a better press fit system where all the best from BB30 and PressFit bottom brackets would be combined into one captivating package. PressFit 30 will feature an integrated seal, pre-assembled into the cups, to further prolong bearing life.

The key difference with PressFit 30 is how the bearings are fitted into the frame. Bearings are housed in nylon cups which will be pressed into the frames bottom bracket shell. This bottom bracket is designed for 30mm spindle cranksets.

Frames will need a 46mm inner-diameter bottom bracket shell to accommodate this system. PressFit 30 for road will require a 68mm wide shell while PressFit 30 for MTB will require a 73mm wide shell."

sungod

andi1363 wrote:

You guys should check things out before giving advice :roll:

"We at SRAM saw the opportunity to make a better press fit system where all the best from BB30 and PressFit bottom brackets would be combined into one captivating package. PressFit 30 will feature an integrated seal, pre-assembled into the cups, to further prolong bearing life.

The key difference with PressFit 30 is how the bearings are fitted into the frame. Bearings are housed in nylon cups which will be pressed into the frames bottom bracket shell. This bottom bracket is designed for 30mm spindle cranksets.

Frames will need a 46mm inner-diameter bottom bracket shell to accommodate this system. PressFit 30 for road will require a 68mm wide shell while PressFit 30 for MTB will require a 73mm wide shell."

hmm, if you had checked things out you would know that...

while the pressfit 30 shell for road is 68mm wide, it is NOT a traditional bb shell

it's yet another style, designed to accept pressfit 30 cups, so the bearings are inboard and bb30 cranks will fit fine, like this...



this pf30 adapter to allow fitting standard threaded cups shows how large pf30 is vs. the standard bb



the standard 68mm threaded bb will have the bearings outboard and so be too wide for bb30 cranks

there are some bb30-compatible cranks that have longer spindles and so can be used ( some modification may be required) with external cups on traditional threaded bb, but that's specific to those cranks, not to bb30 cranks in general

Pokerface

Monty Dog wrote:

BB30 uses press-fit bearings. You can't use BB30 cranks on a regular 68mm bottom bracket shell as they simply aren't designed to fit - the BB30 shell is oversize and 68mm wide - designed for the bearings to fit internally - there simply isn't enough room between the 30mm spindle and a regular BB shell to fit the bearings. You can however get an adapter to allow you to use a conventional chainset or external bearing BB in a BB30 frame - confusing, eh?

There are adapters available that allow you to use a BB30 chainset on a BSA24 frame. (Rotor do one and I have the cups sitting in front of me).

Pokerface

papajimbo wrote:

You may be right, this is the link:

http://www.tredz.co.uk/productlist.aspx ... ts&f5=BB30


They're all over the place, cheapest from the ebay retailers. Let me know what you think.

Those cups are SRAM's twist on the BB30 standard. My research last night led me to understand that these cups will fit on specific frames. They press into the frame - but they need a 46mm diameter BB (instead of a standard 42mm shell that most BB30 frames will have).

Unless you know your frame uses this standard, I would stick with the regular press-in bearings, etc.

sungod

Pokerface wrote:

There are adapters available that allow you to use a BB30 chainset on a BSA24 frame. (Rotor do one and I have the cups sitting in front of me).

sounds like the rotor bsa30, but it's external cups, it is for cranks that have a longer spindle than needed for standard bb30

rotor's 3d+ cranks have a long spindle, so that they can be used with several different bb types, on a normal bb30 you need to use spacers with them, with the bsa30 i guess you'd remove some/all of the spacers

but a bb30 crankset with spindle length designed for bb30 (i.e. without needing spacers), will not work with a bsa30, because the spindle won't be long enough

example, given two bb types...

a) bb30, width is 68mm

b) bsa bb, width is 68mm + width of the external bearing cups, say 9mm each cup, 86mm total width

if crankset has a spindle only long enough for a), then the spindle will be 18mm too short for b), so it won't fit

Monty Dog

I agree, you simply cannot fit BB30 to a conventional BS68mm shell - there simply isn't room for the bearings, regardless of what other posts have suggested. Frankly, BB30 is cr@p and soon we'll see everyone adopting BB86 which is far more sensible - there is a reason the likes of Shimano don't make one