BB for Frame

[funkymonkey]

Hi all,

I have just picked up a Raceline Ext DH frame for cheap from a mate. I think it is an 02 or 03 model, With a DNM reart shock.

I have been looking everywhere to find the size of BB i should buy for it.

I am just getting into downhill, and cant find any specs.

I have also noticed a few different size BB's out there.

Any help would be appreciated, or somebody tell me where to measure.

Thanks.

[russthedog]

ii dont know exactly what size bb you got, but most common BBs should fit in there. ones like the gigapipe fit onto several different sized bbs, via spacers and orings. most will fit both a 68 or 73mm shell, and the spindle width you want is probably 113 or 118mm...im not sure but i think either might fit most the time. otherwise see if you can get the technical specs off the net....some wild biking fiend might be more heplful than me but :confused:
good luck dude

[donthucktoflat]

ok. measure the width of your BB shell. it should be either 73 or 68mm wide. try emailing raceline. they should have the tech info you need

[Grip]

Standard bottom brackets are specified in terms of width of the bottom bracket shell of your frame (generally 68, 70 or 73 mm) and the length of the spindles are (most commonly) 102 - 130 mm

Current usage generally assumes that 68 and 73 mm bottom bracket units are for British/ISO threaded frames, and that 70 mm units are for Italian threaded frames (you do NOT have one of these so forget 70mm). Measure the bottom bracket shell on your frame and get one to suit either the 68 or 73mm length.

NEXT...

The spindle length of the bottom bracket you need depends on what kind of crankset you'll be using, AND the frame itself. The whole idea is that the spindle length varies so as to get the chain line right.

Chainline is measured from the centerline of the frame (Downtube or seat tube) to the center of the chain. You can measure the front chainline easily with a simple ruler. Simply hold the ruler against the seat tube or down tube and measure the distance to the middle of the chainring teeth (IF you're running single front chainring). In the case of triple chainwheel sets, measure to the middle of the middle chainring. In the case of doubles, measure to the halfway point between the two rings.

If you're planning on running a Shimano spec drive train you need a bottom bracket spindle length that sets your chainrings up at between 47.5 and 50mm from the centreline of the frame (measured as per the instructions above).

For frames with oversized seat tubes you'll need a longer spindle length, because the fat tube places the derailer mechanism farther to the right. OR you'll set it all up using a derailleur that mounts to the bottom bracket itself and that way the width of the seat tube doesn't matter.

There.... simple, eh?:confused:

[donthucktoflat]

wow grip, thanks, that was really helpful, i also loved the way you used giant letters. you rule :D

lol, jks, but seriously, that was good info. i always wondered how the 113/118mm bit was worked out

[Grip]

Riiiiiiiiigggggghhhhhtttttt. What giant letters? You lost your glasses again or just been out feeding the chooks?

[donthucktoflat]

Riiiiiiiiigggggghhhhhtttttt. What giant letters? You lost your glasses again or just been out feeding the chooks?
in the second half.. werent there.. i thought.. dammit.

YES, THERE ARE BIG LETTERS! look at the bit from chainline onwards. see? bigger. :p

[funkymonkey]

Thanks Guys, that does help. Now to part with some $$$$.

I have emailed raceline already, but have been waiting about a week.

Doesnt matter now i know to measure it.

Thanks.