Miyata with holes in bb shell

[Thunderchild]

Howdy all,
Anyone know what the holes in the bottom bracket shell are for on this Miyata?

http://cgi.ebay.com/Koga-Miyata-Gents-r ... dZViewItem

Thanks

Thunderchild

 

[JS1500]

So the hamster that moves the axle can breathe.

 

[Stick Legs]

Many bikes have holes or slots in the BB shell.

1. Weight saving on lightweight specials.
2.To let water drain out of the frame, only useful on cartrige BB bikes. (My Orange has this feature).
3.Fashion.

Those are the only reason's I know.

 

[Elev12k]

Thunderchild,

Both my 81 ProRacer and my 84 ProRacer-S have those holes.

Showing the 81 ProRacer:

Topic on this bike, with many pics

My ex pro 80 Koga Miyata FullPro-L even has 'M's cut out the shell, like shown on this bike in the 1978 Miyata Jp catalogue:

Here, in the Retrobike Gallery

As Stick Legs says, it probably has to do with weight saving. Moreover the Japanese are very into perfectioning and detailing and that will pretty sure also have something to do with it.

More Japanese brands do this, for example Nagasawa:

Another:

 

[Thunderchild]

Thanks for the pics Elev12k. In my 20 years mtbiking, I have never seen such frames. I have been so sheltered... Seems like dirt, water, earthworms, shrews, beetles, etc. might find their way in to the bb bearings, threads, etc.

Later
Thunderchild

 

[Elev12k]

The bearings are covered and always use sufficient grease when you mount a BB.