bmx bb vs mtb bb

Dane

Dane

Likes Dirt
Right... i've just spent the last half hour or so trying to find some info on the differences between bmx and mtb bottom brackets. I've been playing with the search thing and have had no luck. What i would like to know is, what are the pro's and cons of the two bb types?

I am asking this as i have plans to build a bike up within the year and am searching for a frame atm. The bike is going to begin its life as a single speed DJer. then possibly become a 9 speed (or so) when i can afford some SRAM. I would be running a ss conversion kit (or similar - not a ss hub). and i would like to get cranks that i can chuck a good bash guard and chain guide on to.

so wich bb would suite me best?
any other thoughts, feel free to share ;)

Cheers
Dane!
 
RaID

RaID

Likes Bikes and Dirt
your gonna have problems chucking a boomerang type chainguide on a BMX BB type frame

the only chainguides available for BMX BB frames as far as i know are the DMR that mount on seat tube like a front deraillure type mount
 
LTR

LTR

Annoys the hell out of Grip!
well if your getting a chainguide, then you might want the mtb bb becuase there will be a lot more of a choice, although im guessing you might want horizontal rear dropouts and most horizontal dropout frames these days come with bmx bb!

good luck!
 
Dane

Dane

Likes Dirt
live_to_ride said:
although im guessing you might want horizontal rear dropouts and most horizontal dropout frames these days come with bmx bb!

good luck!
Click to expand...
bah :x


ok what sizes are your convetional bmx and mtb bb?
and say i ignore the chain device issue for now, what are the other pros and cons?... (to do with cranks?)
 
S.

S.

ex offender
iLikeBasS said:
live_to_ride said:
although im guessing you might want horizontal rear dropouts and most horizontal dropout frames these days come with bmx bb!

good luck!
Click to expand...
bah :x


ok what sizes are your convetional bmx and mtb bb?
and say i ignore the chain device issue for now, what are the other pros and cons?... (to do with cranks?)
Click to expand...
MTB advantages:
- Lighter
- Easier to get a chainguide for
- BBs actually have "standards" so they won't only work with the cranks they come with
- Threaded cups (can be good or bad), good in that it's easy to install/remove, bad in that you *can* cross thread the frame (if you're clumsy enough, and you really do have to be VERY clumsy!) and cause a lot of dramas doing so.
- Wider range of cranks

BMX advantages:
- Much bigger bearings
- arguably stronger (but not in all cases)
- Can get reducer cups so you can choose from mtb OR bmx cranks/BBs, but be aware that these alter your chainline slightly (very slightly).

Personally I don't see much reason to go for a BMX bb over an MTB one, especially if you plan to run gears.
 
CHEWY

CHEWY

Eats Squid
More surface area to weld tubsets/stays onto with the BMX BB = More strength.
Longer lasting bearings in the BMX BB
Fat axels
Opens up the doors to a wide range of BMX cranks
 
fastrider gus

fastrider gus

super huck
BMX! i love them... pitty i have a mtb now...
BMX cranks are usualy cheaper for some reason too. but trailers at the local races dont like tubular cromo cranks..
 
S

stinky|dan

Likes Dirt
mtb! I have DMR chieftains on my .243 (mtb bb) and they are easy to install and service because you can just unscrew the cups. ON a bmx bb they are just shoved in there and are more difficult to fix/ repair/ remove.

It very much depends on what FRAME you want. .243 has both options with horizontal dropouts and single speed chain tensioner.
 
Dane

Dane

Likes Dirt
.243 is definately one i'm thinking about (sorry naz). just trying to get an idea of which bb would be my best option.
 
5PIDEY

5PIDEY

Likes Dirt
i think either blackspire or evil or something make really good chain guides for bmx bb. i have a bmx bb and they are really good but the only problem with them is getting parts like bashguards.[/quote]
 
R

Rik

logged out
BMX bb... I dislike a fair bit. Press fit everything, it's really sloppy, you have headaches trying to adjust bearing preload whilst keeping your cranks tight. When it works, it works good, but when things don't fit together like they should (which I'm having issues with right now), it's a nightmare.
You can now get any decent BMX crankset with a euro(mtb) BB, so that's a moot point.
I'd say MTB bb, to save hassles... even though I do like bigger bearings, it's not worth the hassles that come with them.
 
roasted

roasted

Likes Bikes and Dirt
ok BMX cranks are cheaper. bigger bearings
I researched this part:
MTB (bmx style tho) equals: stronger, lighter (50grams), standardized, easier to install, replace....
The only reason for BMX BB is:(wait for it)


the ability to run ONE PIECE CRANKS.
hence cheap, cheap mtbs having bmx bb's.

ya know its strange how as BMX moves to MTB STyle gear, MTB suddenly goes BMX.




www.fatbmx.com has the lowdown
hard to find it tho
 
T

Tankass

Likes Dirt
actually it hard to say which bb is better. the bmx industries are now shifting more and more towards the euro bb trend as they find it lighter,and strong as well.(those crmo 3pcs euro bb with dual bearings on each side.eg dmr/profile/funn/aireal etc etc)
and on the other side,some mtb frame makers have claim that bmx bb is much stronger thus coming out with more and more frame models using usa bb.so which is actually better?or issit that it depends on the type of riding we do?or issit jus some marketing strategy?
 
S

stinky|dan

Likes Dirt
.243 dropouts are the same. Only the BB and top tube length change!

Good point also that a lot of the best BMXs are coming out with euro (mtb) bb/s. This means that there might be a few new options for us mtb's who need a bit more variety in the 3 piece crank market.
 
5PIDEY

5PIDEY

Likes Dirt
roasted said:
ok BMX cranks are cheaper. bigger bearings
I researched this part:
MTB (bmx style tho) equals: stronger, lighter (50grams), standardized, easier to install, replace....
The only reason for BMX BB is:(wait for it)


the ability to run ONE PIECE CRANKS.
hence cheap, cheap mtbs having bmx bb's.

ya know its strange how as BMX moves to MTB STyle gear, MTB suddenly goes BMX.




www.fatbmx.com has the lowdown
hard to find it tho
Click to expand...

are you saying my bike is crap matt?
 
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