Measuring the rim
 

How do you measure the rim? Sorry

Two ways, either by the tire size, which means knowing or measuring the overall diameter, and working back about 6-8mm for the bead seat diameter and comparing it to standard sizes here. You also want to know the inside width, but this isn't as critical since each width can accept a range of tire widths, running form about 1.5x to over 2x the inside rim width.

For wheel building, you need to know the spoke hole diameter, or if using a spoke calculator the ERD (effective rim diameter). The easiest way to measure this is to drop a nipple into a hole, measure the overall diameter to the edges of the rim. lay a straightedge across the rim and measure the drop to the nipple. Subtract 1-2mm from this to have an ERD between the slot and top of the nipple.

Whenever measuring rim diameters, it's best to take two measurements at right angles in case the rim is slightly. The round diameter is the average of these.

I assume that you are referring to measuring the rim width in reference to your earlier tire question post rather than the diameter of the wheel. To measure that, it's easiest to remove the tire and measure the inside measurement of between the rim walls with a caliper or with a tape measure. You could also deflate the tire and measure the width without removing the tire. You'll have to subtract wall thickness from the outside measurement to get the inside measure. Each wall is 2.5 mm so subtract 5 mm for the overall width.

ETRO standard is the Bead Seat Diameter, so you look inside the rim, to find that. make a Sharpie mark on the outside,
then measure between those marks.

I am working on building a set of Araya 700c 2w rims with Shimano 105sc hubs. Applied the above methodology and came out with 520mm. 250m spokes on each "pole" with 20mm gap in the middle. Everything I that I have been able to find about this rims suggest 611mm

What am I doing wrong?

One method would be to go to your local DYI and get a 3' length of 1/8" rod. Then place this rod through one spoke hole and into the opposite hole. Mark the rim's nipple beds on this rod, remove and measure this length along the rod. Repeat at least two more points around the rim.

Or you can google the rims and you get this link which claims 602mm ERD. This only took me about 1 minute. Andy.

https://leonard.io/edd/rim/277-araya-adx-2w-700c

I have no idea, but a 700c rim should be a hair under 640mm in overall diameter (to rim edges). The depth to to the nipple seat is a few millimeters less than the overall depth of the rim. Allowing for the head of the nipple, you'd subtract 3mm more. So if the rim is about 20mm deep (not saying it is), you should be coming up with something close to 640 - 2x12 mm or about 616mm ERD.

I have no idea how you got to anywhere under 600mm unless they were very deep rims.

I was using the link as my reference guide....I did the "spoke measurement method" as a way to confirm. I just don't see how i am off by 50+mm. Will double check my work, again.

Exactly!!! Has to be operator error!

Page 44 in the Rohloff Manual shows a simple way to measure . the distance between spoke seats..

It involves the rim in question , 2 nipples * and 2 spokes ** and a caliper.. to measure how far apart the gap is between the spokes
in holes into opposite sides of the rim.

*Nip head thickness and ** spoke length .. measured , so Known.


http://www.rohloff.de/en/service/dow...ion/index.html

There are MANY ways to measure a rim for ERD. But all share a common trait. However you measure and/or calculate you have to do it correctly and consistently.

It isn't how you choose to measure, it's how well you do it.

Which is exactly what the "thread reviver" stated in post 5

I got the book .. so I can say what page (oddly I seem to find the German one easier than I can lay my hands on the one in English)

Broke the hammer with that post.

Since we are all brothers here....I kinda didn't convert cm to mm. confirmed to Andy's number.


I am 235, this is for an '84 Fuji steel/quad-butted. I doubt this bike will get more than a 1000 miles annually on flat paved roads.

Should I do 2 or 3 crosses?

Was planning on using Wheelsmith DB14 - Thoughts>?

RULE 37- Go with the basics unless you have a reason to change.

Over 99% of 32h wheels are built 3x, so unless you know of a reason to depart from that you might as well stick with SOP. WS 14g DB are excellent general purpose spokes and should more than adequately serve your needs, especially for a bike ridden less than 1,000 miles / year. As far as your weight goes, consider that I build tandem wheels for cross country loaded touring using the same spokes.

How many holes?
If 32-36 I'd just stick with X3.
On the front, you could go X2 and save about 1/2 spokes worth of weight.

erd
 

An $80.00 solution to a $2.00 problem. Otherwise basically similar to the method I described and have been using for almost 50 years.

erd
 

I've used a number of different ERD measuring methods over the years. Wheelsmith's rods, Southerland's tape, Sheldon's spokes, DT's chart w/ nipples and the straight rod one I already posted. I fall back on DT's chart, lately often with a double check using the Southerland system. (I just had my original DT chart laminated and photo copied). As has been mentioned how one uses whatever system is most important. Getting use to the nuances of the tools one uses takes time and repetition. It is this step that most newbies avoid or don't have the chance to do. Andy.

Triple confirmed that a 3 cross calls for 297.4mm. Should I round up to allow for the greatest margin of error?

Suggestions on nipples?

I usually round in the direction of my concerns about accurate ERD. If you have two different ERDs (close but different) round in the direction of the one you decided to not go with.

Brass nips always. Andy.

That's what I get for the front.
Have you noticed the rear is different?

I typically round up, using Spocalc.

Since the rear NDS only has about 56% as much tension as the DS, I'd use a thinner spoke on the NDS.
My typical recipe is 14/15 DB on the DS and 15/16 DB on the NDS and front.
I get my spokes here, since it's easy to mix & match-
Bicycle Spokes | The Colorado Cyclist

12mm or 14mm?

There's no benefit to longer nipples except to hide the threads when the spokes are too short. In fact longer nipples can work against you because they reduce the overrun possible if the spokes are long.