110.5mm to 110mm Bottom Bracket

[Moon]

I need to replace my 110.5 mm bottom bracket. There is more choice and a lower price for 110mm bottom brackets. Can I use the 0.5mm shorter one. Is the difference a simple 0.5mm or is there a reason for the very slight different size?. Thanks

[nfmisso]

0.5mm is not going to make a significant difference.

You do not mention the type of bike, but if derailleur equipped, even 5.0 mm is not going make much difference.

[Moon]

Thanks. Its a Scott mountain bike. I am just confused as to why both sizes exist with such a small difference between them. If the only difference is 0.25mm on each end the 110mm should be fine.

[RobAR]

It all boils down to how precise a manufacturer likes to get. Shimano may lable it a 110 and YST may say 110.5mm.
The (popular) nominal sizes for square taper spindles are 107, 110, 113, 115, 118, 122 and 127. You can safely ignore any decimal points.

In laymans terms, Spindle length required is mostly determined by the amount of clearance needed between the chainrings and the right-side chainstay of the frame. Most bikes can be fudged a bit in either direction without exploding but, shifting performance may suffer. That's getting into chainline science and is a topic for another day. Was that Too Much Info?

[Moon]

Thanks. 110 it is then. I expect the tiny difference, if there is any, is less than the play in the current worn bottom bracket. The smallest distance between chainring or crankarm and frame is about 7mm so it should be fine. Thanks for clarifying.