Press fit on older threaded BB shell

Posted on
  • Hello, I'm going mad trying to fit new press fit cranks on a caad 9 frame, with threaded BB shell. I have bought a rotor BB/ converter which I have fitted to the frame, https://www.wiggle.co.uk/rotor-bsa30-bot­tom-bracket-cups-steel/?lang=en&curr=GBP­&dest=1&sku=5360740730&kpid=5360740730&u­tm_source=google&utm_term=&utm_campaign=­Shopping+-+All+Products&utm_medium=base&­utm_content=mckv|ssR2w6YUC_dm|mcrid|2952­92317327|mkw||mmt||mrd|5360740730uk|msli­d||&mkwid=ssR2w6YUC_dm&pcrid=29529231732­7&prd=5360740730uk&pgrid=58852352866&pta­id=pla-522561790471&gclid=Cj0KCQjww47nBR­DlARIsAEJ34bk0OsoG7N0aZ4zq58zQ46E1Xv3y6T­j_qb7CzApnJuVQwShdlXHX8hwaAt_UEALw_wcB
    Trying to fit some cannondale SI spider ring cranks with 109mm spindle, however this comes up too short once the rotor cups are on.
    Also it seems that the drive side would sit quite far apart from the frame, making the small chain ring nearly an inch off the stays, which seems weird.
    I'd be grateful if anyone could shed some light on this. Do I just need to get a longer spindle? What's the deal with the ring so far off? I don't mind having to look for different cranks if necessary. Thanks.

  • you have bought BSA30 cups. There is no such thing as press fit cranks. you don't press fit the crank in do you.

    BB30 cranks meant for BB30 press fit bearings into the frame wont work.

    You need cranks made for the BSA30 standard. i.e cranks with axles the length of hollow tech II but 30mm in diameter. Rotor and praxis do these.

  • Bit patronising but very helpful, thank you!

  • I don’t think you can fit the Si cranks to a BSA frame - the axle is too short to cover the use of external cups as you have discovered or if you get an axle long enough the chainline goes out of whack and the FD will not work.

    Admittedly it was much simpler when they only made the 104mm axle for 68mm shells and it was crystal clear that they would only ever work in a proper BB30 shell.

    The BB30a shell for which the 109mm axle was made has 5mm added to it making it 73mm... but it’s added to the non drive side - the spider is in the same plane as it always was on the og 104mm axle.

    Tl;dr cranks won’t work in your frame

  • you don't press fit the crank in do you.

    Hah I’m guessing you’ve never had to install the original Hollowgram crank then! Much bashing with a hammer after freezing the axle for hours...

  • Thank you both. Should I just look for any Praxis cranks for bb30 BB then? Will they come with the right spindle lenght or do they make them in different sizes? @Howard @cycleclinic

  • Force 22 bb30 cranks work with bsa30 and the correct spacer arrangement

  • Thank you. Would Red not work then?

  • If you've got a BSA frame and you're buying new cranks anyway, why not just get GXP rather than BB30?

  • Uh yeah probably but you need to be careful about which ones you get. The 11 speed exogram ones, yeah.

  • isn't he right in saying if just needs the longer spindle ? spacers required though

    but indeed, if new cranks required, probably better off buying gxp ones, fit and forget.

  • isn't he right in saying if just needs the longer spindle ?

    No :)

    Already sunk money in to the BSA30 cups so might as well use them

  • Sorry you mentioned gxp cranks but would they not have a 24mm spindle? Meaning that I would need an adapter for the cups to reduce diameter? Thx @PhilDAS

  • Meaning that I would need an adapter for the cups to reduce diameter? Thx

    No you'd need a normal bottom bracket, not the rotor one which is an adapter in itself. 30mm cranks are not designed for BSA shells.
    Use a normal BB30 crankset with your BSA30 BB or buy 24mm cranks and a new bottom bracket.

  • Should I just look for any Praxis cranks for bb30 BB then

    No, because Praxis cranks are only 30mm on the drive side bearing, stepping down to 28mm on the non-drive side bearing.

    Therefore they're only usable with the Praxis BBs (pressfit or otherwise) and not the Rotor one you've bought.

    Isn't this fun :)

  • Thanks, so what cranks are to be used with the Rotor BB I bought? I'd like to avoid having to buy another BB...

  • Haha this is a nightmare! So do you know if I can use any cranks with the Rotor cups I have? Thank you.

  • Any BB30 crank pretty much. Or replace the axle on the SI cranks, or just fit a 5mm spacer on the NDS

  • to my knowledge, cranks which are gonna work on your rotor bsa30 are : rotor 3d30, and sram PF30

  • Any BB30 crank pretty much. Or replace the axle on the SI cranks

    No and no.

    Any BB386 like crank will work. This includes most but not all 30mm axle SRAM cranks, which were along with rotor effectively the BB386 axle length before FSA stuck a name on it.

    Any legit BB30/a will not work.

    Can’t replace the axle on the Si crank because the crank spider ends up too far out on the drive side for the FD to work and to have a workable chainline.

  • Rotor cranks that would fit are the 3DF, 3D30, 3D+, Flow. I guess their new 4-arm cranks too.

    Unless you have a badly undersized BB shell width then those cranks would go on without any spacers and then just an adjustment of the preload ring. But In some cases you may need their 0.5mm plastic spacer on the non-drive-side to fill up some space.

  • 🤷🏼♂️

    Madness to buy a crankset so you can use a specific BB in the first place

  • Very clear, thank you!!!

  • Post a reply
    • Bold
    • Italics
    • Link
    • Image
    • List
    • Quote
    • code
    • Preview
About

Press fit on older threaded BB shell

Posted by Avatar for pooolq @pooolq

Actions