Bicycle Mechanics - How to measure parts?

Some bike parts are sold in measurments that are down to a tenth of a mm. How on earth do people measure these things.

If I wanna measure the width of the hubs, or the size of the seatpost, and all that other stuff, what is it I need?

I cant use a regular ruler............. :D

Some bike parts are sold in measurments that are down to a tenth of a mm. How on earth do people measure these things.

If I wanna measure the width of the hubs, or the size of the seatpost, and all that other stuff, what is it I need?

I cant use a regular ruler............. :DGet a caliper.

Get not simply a caliper, but a metric veneer (sp?) dial caliper. These are capable of giving you extremely accurate measures. They can be found on ebay for around 20-25$ and are worth the price if you do a lot of bike tinkering.

Get not simply a caliper, but a metric veneer (sp?) dial caliper. These are capable of giving you extremely accurate measures. They can be found on ebay for around 20-25$ and are worth the price if you do a lot of bike tinkering.


Are they sold at hardware stores, like the Home depot?

While most parts are measured to .x mm the jumps (except for seatposts) are fairly large. Like front der. clamps: 28.6, 31.8, 34.9 You are unlikely to come across parts that are so close they could be mistaken for each other(Unless you start dealing with really old road frames in swiss or french spec) They are often marked with the size as well, so if you have the old part you can get the # of of it. This is the easiest way to figure a seatpost size.

Get not simply a caliper, but a metric veneer (sp?) dial caliper. These are capable of giving you extremely accurate measures. They can be found on ebay for around 20-25$ and are worth the price if you do a lot of bike tinkering. I've yet to find anything on a bike that cannot be dealt with using an inside/outside vernier caliper and some common sense.And often the latter being more important than .oo1 mm or inches.

I find the accuracy of a veneer caliper extremely helpful when dealing with measurements like the fork crown race on older bicylces and headsets, which can vary slightly depending on national measurements. But then I work largely on older bikes, and as the good reverend notes, you can run across some odd sizing issues on them. I deal with them on a daily basis. I suppose if you're working only on newer stuff, it becomes less of an issue, so a standard caliper should do the trick. You can pick up a general caliper at your local Home depot as well.

im so glad my dad is a tool makers, he has all this measuring stuff. Also my bike came with this sheet of all the parts and measurments

I would recommend a dial caliper. It is easier to read then a veneer caliper. It doesn't have to be metric. Just multiply the reading by 25.4 and you will have the metric size.

Are they sold at hardware stores, like the Home depot?

Yes for about the same price and no S/H to pay. There is a lot of stolen stuff being sold on ebay beware!

I got my digital calipers for $20+tax at the local auto parts store and I use them all the time. In addition I'd definitly recommend a set of metric feeler gauges, they come in hany in so many situations.

A thread pitch set is handy as well.

Harbor Freight, the laughingstock of the metal working
boards, has a metric/english digital caliper that works
as well as my Mitutoyo for $20. It is good to ~0.001"
or 0.025mm. Steve

Harbor Freight, the laughingstock of the metal working
boards, has a metric/english digital caliper that works
as well as my Mitutoyo for $20. It is good to ~0.001"
or 0.025mm. Steve

They may not be too bad for the money but they are not as good as a Mitutoyo. You get what you pay for but then again you don't need an expensive one for bike repair. I personally would not buy one that was made in China or a similar country but that is just because I try to buy American or from countries were the workers make a fair wage.

Starrett is the only precision manual measuring tool
manufacturer left in the US. Their vernier version
of the caliper would run over $100, occasionally available used on Ebay for less. Their electronic version is 2x that. General makes some
middle grade stuff, but not a vernier caliper. Stanley
if you can find any still made in the US, doesn't make
this level of tool, nor Cooper, etal. Sears at one time
did but not in 20yrs. The HF is a throwaway device,
hopefully it will last more than 2-3 battery changes,
which is about all I ever get out of a watch or bike
computer, to which the HF caliper is kin. Steve

sch, how about Fowler? I have some outside mics that i picked up about 12 years ago.
HF and Northern are good for disposables like C clamps. They get burnt and spattered on, and if you damage one, no biggie, it was five bucks.

Reading a metric vernier gauge is fairly basic (non dial/digi.) but an imperial vernier can be more difficult if you dont use them often.

If all you need is to measure the size of a seat post to within 0.2mm and identify the occasional drill bit that you can’t make out the markings on the shank any more then one of the $1.50 plastic ones from most decent tool shops will do won’t it?

sch, how about Fowler? I have some outside mics that i picked up about 12 years ago.
HF and Northern are good for disposables like C clamps. They get burnt and spattered on, and if you damage one, no biggie, it was five bucks.

Most of the Fowler stuff is pretty good. Not as good as Starrett but way better then the cheap stuff. I have a swiss made Fowler digital caliper at work and it works fairly well. Most Fowler products are made in Japan.

Rev Chuck: As Coda1 suggests, Fowler stopped
mfg in USA sometime back. I have a Sherr Tumico
micrometer made in USA but tho the company still
exists they now sell optical comparators. Brown&
Sharpe is another such former maker of Starrett type
stuff, long since departed from the business, now
selling relabeled far east sourced items in a greatly
shrunken line. I did stumble across "Chicago Dial
Indicator" which purports to manufacture dial indicators
and a wide variety of measurement devices made in
USA. They are not in any of my metal work catalogs.
The HF stuff is easy to use for the novice and cheap enough to be throwaway. Steve