# Rack and fender mount - screw size?



## danl1 (Jul 23, 2005)

Putting together a beater / grocery getter for the wife, and hit a question. Y'all are the easiest way to answer.

I'm trying to mount a rear rack on a cheap, early '90's MTB. Brand name on the bike is "Jazz", which I'm told was a second line from Trek back in the day. The seatstay mounts are M5, so no worries there. But the mounting holes down on the dropouts are something a bit larger. Is / was there any sort of standard for those? My first guess was going to be 1/4-20, but a glance suggests the thread might be finer than that.

Thanks.


----------



## cxwrench (Nov 9, 2004)

should be M5, same as water bottle cage bolts


----------



## danl1 (Jul 23, 2005)

cxwrench said:


> should be M5, same as water bottle cage bolts


Ain't. The uppers are, but the lowers, an M5 goes right in, screw major diameter being smaller than hole minor.


----------



## Kontact (Apr 1, 2011)

6mm would be the next obvious choice, but that isn't going to go through a rack. Are the lower ones actually threaded? They might be holes that you put a nut on the other side of.

I used to sell Jazz (we called them 'Jizz Bikes'), but don't recall ever mounting anything but a kickstand on them.


----------



## danl1 (Jul 23, 2005)

Kontact said:


> 6mm would be the next obvious choice, but that isn't going to go through a rack. Are the lower ones actually threaded? They might be holes that you put a nut on the other side of.
> 
> I used to sell Jazz (we called them 'Jizz Bikes'), but don't recall ever mounting anything but a kickstand on them.


Yep, they're really threaded. I'm likely going to end up nutting them as you say. 

No doubt that by adding a rear rack I'm doubling - perhaps tripling - the value on this thing. Just need a spot for the groceries.


----------

