what's this tool called
 

http://www.sheldonbrown.com/images/seatpost-sizer.jpg

i'm looking for this tool, it's for measuring seat posts on frames, if someone could provide a link on ebay or niagara cycle that'd be great, i need one

"Seatpost Sizing Rod" : http://www.universalcycles.com/shopp...s.php?id=40887

Who needs one of those when you already have a collection of seat posts in every conceivable size, from purchasing the wrong size every time?

kool i found it.... still 60-70 dollars on ebay ... #$#^%^$#

anyone here got one for sale cheaper?

Paying your local bike shop to do certain jobs can save you time and money.

http://c.shld.net/rpx/i/s/pi/mp/6271...48699be5998afd

http://www.sears.com/shc/s/p_10153_1...&blockType=G12

Central Tools electronic caliper at Harbor Freight, $10 USD. Maybe they ship to Canada.

i have a micrometer, but i like that tool better...

The digital caliper reminds me that when I measure a post from my comprehensive assortment of sizes, that the stated size is subject to clearance tolerances.
Most posts are nearly 0.1mm smaller than indicated, and most somewhat more or less than that.
I really lucked out this weekend when I needed a 27.4mm post, but found an old Kingsbury/American Classic post in the 27.2mm-stamped size that was actually 27.27mm diameter. It fit really well in the 27.4mm seat tube.
All the other 27.2mm posts I had (10 or so of them) were significantly under 27.2mm.

Note that it's sometimes hard to ascertain the exact post diameter required using the inside-measuring tips of a dial caliper. You usually have to measure many positions and take an average, so it's better just to test fit the biggest post that fits without force.
A slipping post often suggests the need for a different brand of post that's just slightly bigger in actual diameter.

Those $10 calipers are awesome, and I've used mine probably 10,000 times over the last ten years. They cost $20 back then!

Always wanted one of those.

I've always called these seat tube gauges. They measure the inside diameter of the seat tube. They don't measure the post.

:lol:

Measuring the OD of a round tube with digital calipers is often inaccurate and you think that's a good way to measure the ID of a tube? It is not, that's why the seatpost sizing rod exists.

Really? It's not that hard to use a caliper. Machinists use these all the time and get accurate measurements.

My local shop has never charged to check seat tube sizing for me, thankfully they have a huge variety of posts in stock as well.

I didn't say it was difficult to use a caliper. I am unequivocally stating that using $10 Chinese digital calipers is a poor and inaccurate way to measure the inside diameter of a seat tube. That is why they make a specific tool for the job.

+1

^ I'm assuming no one cares about the inside diameter of a seat post and that what they meant to write was seat tube.

Thanks Colonel. Duh. I'm with you on cheap calipers, though. Take a ten dollar bill and light a match to it and you'll be in the same position as buying a cheezy caliper.

Well, to clarify, I wasn't trying to imply that the calipers were an inappropriate tool for the job because they were cheap, but rather because they're not made for taking such measurements.

Ah. Ok. That's strictly my take, then. So, what is the proper tool? One of these things? Strikes me this tapered rod might be slightly inaccurate as well, but I've never tried one. I suppose if I ever had to do it I'd use my Starrett inside diameter gages, but I find my vernier calipers are accurate enough for my purposes.

I believe that's some kind of sado-masochistic sex toy.

...what?

And now how about one in the French sizes? Repetez si vous plaiz: 25.0, 24.7, 24.0, 23.8, 23.0, 22.0 etc

If I recall correctly, we used that as a sort of seat tube reamer/flare more than worrying about the size. To prevent scratching the post, we use it with a screwdriver for leverage and twisted it down into the seat tube. It would slightly flare the entry for the post. Then put post in and tighten the seat clamp/bolt. I used it in combination with a brush/flex hone.

Smaller than Diameter pipe - Wrap tape around pipe till same size as internal diameter - Measure diameter of tape - If hard to find French post buy slightly bigger post and take it to machine shop and have it turned to proper size - Biggest mistake on seat posts is short cuts...

IMHO if you can find them the chromed steel guages are much better than the Alloy ones, and I perfer the guages over calipers.

You can get that same vernier caliper from Harbor Freight for around $15 when its on sale. Its branded Cen-Tech instead, but same manufacturer.

Anyone who can't figure out how to accurately use vernier calipers and instead needs a "sizing tool" shouldn't be allowed to exercise their franchise in a democratic society, IMO.

For accurate sizing, you really want to test the size by clamping down on a post or a sizing rod, noting how much clamping movement is needed to secure the post.
The caliper won't measure easily when the seat tube opening or seat post (think steel post or one that's been well-used/abused) isn't quite round. You'll have to get the guage tips aligned with the tube to get the biggest reading for seat tubes, and likely have to take an average of several readings, so far from the best way.
Those Chinese steel dial calipers seem to be much more than accurate enough if used for things that such a tool is designed for.

Digital Caliper-
http://c.shld.net/rpx/i/s/pi/mp/6271...48699be5998afd

Dial Caliper-
http://upload.wikimedia.org/wikipedi...l_calipers.jpg

Vernier Caliper -
http://upload.wikimedia.org/wikipedi...ssschieber.jpg

Any of the three of these should be more than accurate enough in my experience. If you know how to read the vernier you probably have the skill needed. As far as actual post diameter being under by .1mm or so, it has to be (that's only .004"). A "size to size" fit would surely result in a stuck post.

That would have gotten you a severe reprimand in any of the shops I've been associated with. With very few exceptions, gauges are not intended to used as tools.

"If you don't quit using that screw-driver as a pry-bar, it'll never work as a chisel when you need it!"