View Full Version : Reverse threads on a BB???
dynodon
09-26-2009, 05:37 PM
Help the Mongoose doner bike I was robbing the crakset and BB out of has reverse threads and my Mach1 has standard what do I ned to buy??I'm so confused:rolleyes4:
Radical Brad
09-26-2009, 07:27 PM
Both sides of the BB have reversed threads? Only the chain ring side should be reversed.
Brad
PeterT
09-26-2009, 07:30 PM
A BB usually has one side left hand thread & the other side is normal right hand thread.
Check that the BB cups that you are trying are the correct thread for the sides, and it should work.
PeterT
dynodon
09-26-2009, 08:17 PM
OK so the chainring side should be reversed....right? Is that the same for all BB's? when I look at parts some are "english"?They do come in different lengths also right?How would I determine length if I dont have the original? I guess I need a definition I dont have the Bottom bracket that came out of this bike I assumed that the cranks from my Mongoose doner bike would thread right in well never assume right?
Thanks for your advice guys you rock!
Radical Brad
09-26-2009, 10:05 PM
Besides the threaded and non threaded BB's I have never seen any other differences. if there is a length difference then it must be very slight.
Brad
John Lewis
09-26-2009, 10:29 PM
All you ever want to know about bottom brackets.
http://www.sheldonbrown.com/bbsize.html
John Lewis
PeterT
09-26-2009, 10:34 PM
As Brad has said, any difference in BB length will be significantly insignificant... most BB are made to a standard size, otherwise the crank bolts won't fit properly or work properly.
The important thing about BB is to align them so that there is clearance between your lowest sprocket and your frame, and that they are aligned true to the rear cluster, i.e. not twisting the chain to try and drive it in a straight line.
PeterT
savarin
09-26-2009, 11:50 PM
The actual crank pins come in different lengths. One side is often longer than the other to allow clearance for the gears. Single chain ring has short crank pins triple chain rings use longer crank pins. Theres not much in it but hold the two together and you will see the difference
dynodon
09-27-2009, 08:23 PM
The threads must be bunged up a little......guess I'll call te LBS and see if they will chase them for me.
PeterT
09-27-2009, 09:46 PM
Make your own thread chaser by taking a couple of old BB cups and running a fine cut through the threads with a cut-off wheel, and then weld a bolt onto the BB Cups and you have thread chasers for zip
PeterT
dynodon
09-28-2009, 03:21 PM
Thats a good idea the only problem is I dont have any old bb's just the one I was trying to install. I'm going to my LBS and let them take a look at it.
dynodon
10-01-2009, 05:48 PM
my bottom bracket has the same threads on each side....go figure...
fultondp
10-01-2009, 05:58 PM
my bottom bracket has the same threads on each side....go figure...
So it is right hand threaded on both sides?
Darren
SirJoey
10-01-2009, 07:10 PM
my bottom bracket has the same threads on each side....go figure...Dang, that's a new one on me.
Never heard of that before. :rolleyes4:
http://img384.imageshack.us/img384/7131/sirjoeysigmedij1.gif
PeterT
10-01-2009, 07:20 PM
Sheldon Brown mentions that there are some bikes made with both
http://www.sheldonbrown.com/bbsize.html
Bottom Bracket Threading
Italian 36 mm X 24 tpi right right (wrong!) 70 mm Italian and some high-end French bicycles.
Prone to problems due to the right threaded fixed cup, which tends to unscrew itself in use.
French 35 mm X 1mm (25.4 tpi) right right (wrong!) 68 mm Obsolete, used on older French bicycles.
Prone to problems due to the right threaded fixed cup, which tends to unscrew itself in use.
PeterT
dynodon
10-01-2009, 08:29 PM
So it is right hand threaded on both sides?
Darren Yep never thought it would be...