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How To Run Spanish Bearings, In Euro BB, For Bmx Cranks, On a MTB -Tutorial-

Dec 2, 2010 at 4:16
by Philly  
How to Replace Crappy Euro Bearings On Your Street Mountain Bike with Bmx Cranks
-Race Face X-Type External BB
-Spanish BB Bearing KitRight off the bat go into this project thinking ANY PART OF METAL THAT TOUCHES METAL PUT GREASE!!/Anti-seize where appropriate. If your not sure if you should put grease on it - do it anyway!

First off lets change the bearings in the External Cups
(I had these lying around but if you need to purchase some search for Race Face X-Type External BB)
Unsecure image, only https images allowed: http://tfe.me/image/480_345/CR8195.jpg
I am using Profile 19 mm Cranks And Primo Spanish BB/Spacers


- Get Socket Adapter and a Socket the size of the ID of a Spanish Bearing (19mm or 20mm works)
- Use a Flathead and Hammer to get the old bearings out
- Put the new Bearings in with the Hammer and the Socket( By hitting the socket with the hammer in the middle of the Bearing)

Black Bearings = Spanish
Red = Raceface




This worked perfectly on my dob, Chainline wise.
had just the perfect amount of room to play with, since the External BB will take up some space on the spindle.

-Measure the amount of room you have between your cranks and your BB SHELL to insure you keep your chain line in place.


- Jot down those measurements somewhere for both sides.
- Measure your External BB cups and ad a MM for the Little bit of bearing that will be sticking out
- Compare this to your Old measurements and add Spindle spacers accordingly until the measurements are equal
(These steps will keep your cranks the same space from the Frames BB shell as they were before so your Chain line isn't sacrificed)


Not a lot of people do this next step but I find it very useful in lengthening the life of your Cranks and Bearings. And will also make your Cranks feel sturdier.

- Mock up your Cranks off of the bike using the new Bottom Bracket
- Add spacers accordingly on the Spindle between the BB Cups.(You want them to fit snuggly with the spacers, allowing the cranks to spin with no binding)
(The Spindle spacer will probably be the Length of your Frames BB Shell)


Now if you made the spindle spacer the right Length for the bikes BB shell, when you tighten the cranks they wont bind and put side load pressure on the bearings making them turn slowly and creak.
Instead both cranks will tighten infinitely without crushing the bearings because of the spindle spacers pushing out against the bearings while the Cranks are pushing in equaling out the pressure.

Overtime this will helping to reduce Crank wobble.
(Crank wobble can occur when you do not have this spacer, because you are forced to ride *barley tight* crank arms to keep them from binding and allowing them to spin. Sometimes your cranks will then loosen a little without you noticing and you will be riding on them loose and wearing out the spindle's splines)

But Now with this little spacer/spacers, your Cranks will spin freely even after you tighten the shit outa them!

(might take you a few cuts and spacers to get this perfectly right! be prepared to take on and off a few times)

- Put it all on the Bike!



- Marvel at how stiff your cranks are
- Go Shred!


Disclaimer: I am not responsible for you dying or anything of the sort from trying this mod

I have ridden it hard for over two riding seasons and it has never had maintenance and still feels solid.

Learn from my mistakes though,
don't be like me grease your parts regularly kids.

- Philly

Author Info:
Philly-bnb avatar

Member since Oct 11, 2007
1 articles

  • 1 0
 This is possible to do with any bb cups that screw into a euro type frame (apart from euro obviously)
This is possible to do in reverse also, fitting mtb bearings into a spanish frame.
  • 1 0
 very very good advice, does this only work with raceface bbs or other similar ones?
  • 1 0
 Shimano Will probably Work i think
  • 1 0
 Possible to do in reverse?

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