bolts

[Edd]

I'm wanting to replace various bolts on my tri bars, what do I measure to work out whether they are
M4, M5, M10 etc. e.g. what will be the expected diameter for an M4 bolt.

 

[Jobst Brandt]

Edd Shackley writes:

> I'm wanting to replace various bolts on my tri bars, what do I measure to work out whether they
> are M4, M5, M10 etc. e.g. what will be the expected diameter for an M4 bolt.

The M indicates a metric screw whose diameter in mm is the designation. The thread is given
in mm pitch.

Given only M4 the default pitch is assumed but you could have an M4x0.7 or M4x0.5

Jobst Brandt [email protected] Palo Alto CA

 

[Chris Zacho "Th]

Any store that sells machinist tools (and many hardware stores) have charts and cards that have the
common screw/thread sizes on them. As well as major diameters and drill/tap sizes.

May you have the wind at your back. And a really low gear for the hills! Chris

Chris'Z Corner "The Website for the Common Bicyclist": http://www.geocities.com/czcorner

 

[Lindsay Rowland]

Edd <[email protected]> wrote:
: I'm wanting to replace various bolts on my tri bars, what do I measure to work out whether they
: are M4, M5, M10 etc. e.g. what will be the expected diameter for an M4 bolt.

To clarify, 'M4' means metric 4mm (millimetres). Generally metric bolts and nuts are sized in whole
increments, ie, 2, 3, 4, 5, 6, 8, 10, 12, etc so you don't need high precision to gauge them. So, to
size a bolt, simply measure the nominal diameter of the thread. Why not take one of each bolt to a
place that sells metric fasteners and get the assistant to match them?

Cheerz, Lynzz

 

[John McGraw]

Lindsay Rowlands <[email protected]> wrote in message
news:<[email protected]>...
> Edd <[email protected]> wrote:
> : I'm wanting to replace various bolts on my tri bars, what do I measure to work out whether they
> : are M4, M5, M10 etc. e.g. what will be the expected diameter for an M4 bolt.
>
> To clarify, 'M4' means metric 4mm (millimetres). Generally metric bolts and nuts are sized in
> whole increments, ie, 2, 3, 4, 5, 6, 8, 10, 12, etc so you don't need high precision to gauge
> them. So, to size a bolt, simply measure the nominal diameter of the thread. Why not take one of
> each bolt to a place that sells metric fasteners and get the assistant to match them?
>
> Cheerz, Lynzz

That way you would also get the correct lengths. Your bolts are probably metric course, but make
sure the replacement is the same pitch, by laying the threads together and looking through the
interface toward a light or bright surface. As you probably know, with SAE threads the higher the
number after the diameter the finer the pitch. Such as a ¼ - 28 is finer than a ¼ - 20, but w/
metric the higher the # aft. the dia. the courser the pitch. The 2nd # with metric is the actual
dimension from thread to thread in mm. So an M4-.5, is 0.5 mm from thread to thread and is finer
than an M4-.7 Hope this helps John.