Measuring Matrix 750 700c ERD (622x19)
09-07-19, 04:59 PM
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Measuring Matrix 750 700c ERD (622x19)
I've been trying to find an effective way to measure the ERD on my Matrix 750 700c. Before you guys quote the numbers online (544.3mm in Spocalc.xls), I've found them to be incorrect. There were other people indicating those numbers to be suspect. The other value I found was 604mm, which was too much. So I measured the ERD in two places using two spokes. I used a sharpie marker to paint the EXPOSED portion of the spoke while it was inserted into the rim. I started my measurement where the paint started on the spoke all the way to the end of the spoke. I ground down the end of each spoke to 27.5mm.
I then used a ruler to measure end-to-end and I got 44mm. So Total I'm getting 594mm. I measured both ends and I'm getting the same. I guess my question is there anything else I'm missing. I have pictures here. You see on my spokes the unpainted (silver paint) is the side that is hidden in the rim, while the painted side is exposed. I held the spoke as level as possible resting on two bottle caps and I got 44mm.
If anybody have these rims or has some data somewhere with exact ERD that would be appreciated. In addition is there anything I'm missing in my measurements?
The silver painted side was made by spinning the spoke in the rim while using a silver sharpie marker to mark the exposed spoke nipple. the top of the paint is where the spoke nipple is exposed. The spoke nipples were glued with superglue.
I then used a ruler to measure end-to-end and I got 44mm. So Total I'm getting 594mm. I measured both ends and I'm getting the same. I guess my question is there anything else I'm missing. I have pictures here. You see on my spokes the unpainted (silver paint) is the side that is hidden in the rim, while the painted side is exposed. I held the spoke as level as possible resting on two bottle caps and I got 44mm.
If anybody have these rims or has some data somewhere with exact ERD that would be appreciated. In addition is there anything I'm missing in my measurements?
The silver painted side was made by spinning the spoke in the rim while using a silver sharpie marker to mark the exposed spoke nipple. the top of the paint is where the spoke nipple is exposed. The spoke nipples were glued with superglue.
09-08-19, 09:29 AM
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Steel is real
That's how i determine ERD, but i think you've measured the spokes wrong. it should be taken from the top of the nipple or rather the bottom of the flat where the screw driver goes in the nipples [not where you marked them with silver paint]
Last edited by le mans; 09-08-19 at 09:55 AM.
09-08-19, 09:58 AM
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I wonder if 544.3mm is the figure for 650C/ISO 571 rims.
09-08-19, 10:21 AM
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Take 2 spokes of known length.
Secure the nipple with the end of the spoke at the screw driver slot.
THEN, use your method.
I just use a caliper and "pull" the 2 J bends together and read it.
(2X spoke length + caliper reading - 1 spoke dia.)/2
Secure the nipple with the end of the spoke at the screw driver slot.
THEN, use your method.
I just use a caliper and "pull" the 2 J bends together and read it.
(2X spoke length + caliper reading - 1 spoke dia.)/2
09-09-19, 05:52 PM
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So Bill, and TS,
I always just put a metric ruler in the rim and measure the inner dimension of the rim and add 2mm for the rim thickness of the metal. What am I missing??? Smiles, MH
I always just put a metric ruler in the rim and measure the inner dimension of the rim and add 2mm for the rim thickness of the metal. What am I missing??? Smiles, MH
09-09-19, 06:42 PM
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@steppinthrax, it wasn't 650C, but I was on the right track! 
Based on that, I would predict the ERD of a 700C Matrix 750 to come out around 607mm.
@Mad Honk, it depends on what you call "ERD" -- ever since Jobst Brandt, we tend to include the length of the spoke within the nipple head, so if the rim were 2mm thick, a lot of us would be adding about 5mm to the measurement you get at each end.
Based on that, I would predict the ERD of a 700C Matrix 750 to come out around 607mm.
@Mad Honk, it depends on what you call "ERD" -- ever since Jobst Brandt, we tend to include the length of the spoke within the nipple head, so if the rim were 2mm thick, a lot of us would be adding about 5mm to the measurement you get at each end.
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09-09-19, 09:50 PM
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As already noted...
Two spokes of known length.... S1 S2
Two 12mm standard profile brass nipples....
Put spokes into the rim opposite sides, set the nipples such that the spoke end comes right up to the bottom of the screwdriver slot.
Grab both spokes using a set of calipers...snug em up tight...make sure you do so in plane with the rim...not above or below, we'll call this caliper reading . . . CR
S1 + S2 + CR = Guestimate in mm's
Rotate by a couple holes on each side...and again do so...grabbing 3-4 readings in different positions gives you a better picture.
Assuming its a regular rim with holes on center or almost on center, plug your number into the spoke length calculator.
=8-)
Now if you are using very old 10mm nipples, or going 14mm or 16mm, or using a different type of nipple altogether...then test the nipple / spoke thread behavior in terms of max insertion and minimal insertion....determine how to the get the 1.5mm to 2.0mm overhead you need....and then set your nipples and make your measurements.
Ultimately, ERD is about what worked for the wheel NOT about the rim.
=8-)
Two spokes of known length.... S1 S2
Two 12mm standard profile brass nipples....
Put spokes into the rim opposite sides, set the nipples such that the spoke end comes right up to the bottom of the screwdriver slot.
Grab both spokes using a set of calipers...snug em up tight...make sure you do so in plane with the rim...not above or below, we'll call this caliper reading . . . CR
S1 + S2 + CR = Guestimate in mm's
Rotate by a couple holes on each side...and again do so...grabbing 3-4 readings in different positions gives you a better picture.
Assuming its a regular rim with holes on center or almost on center, plug your number into the spoke length calculator.
=8-)
Now if you are using very old 10mm nipples, or going 14mm or 16mm, or using a different type of nipple altogether...then test the nipple / spoke thread behavior in terms of max insertion and minimal insertion....determine how to the get the 1.5mm to 2.0mm overhead you need....and then set your nipples and make your measurements.
Ultimately, ERD is about what worked for the wheel NOT about the rim.
=8-)
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5000+ wheels built since 1984...
Disclaimer:
1. I do not claim to be an expert in bicycle mechanics despite my experience.
2. I like anyone will comment in other areas.
3. I do not own the preexisting concepts of DISH and ERD.
4. I will provide information as I always have to others that I believe will help them protect themselves from unscrupulous mechanics.
5. My all time favorite book is:
Kahane, Howard. Logic and Contemporary Rhetoric: The Use of Reason in Everyday Life
5000+ wheels built since 1984...
Disclaimer:
1. I do not claim to be an expert in bicycle mechanics despite my experience.
2. I like anyone will comment in other areas.
3. I do not own the preexisting concepts of DISH and ERD.
4. I will provide information as I always have to others that I believe will help them protect themselves from unscrupulous mechanics.
5. My all time favorite book is:
Kahane, Howard. Logic and Contemporary Rhetoric: The Use of Reason in Everyday Life
09-10-19, 04:28 PM
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Ah yes Scotty,
Thanks for beaming me aboard! I have not been using a lot of gusseted rims lately and forgot about the extra distance they propose for a good measurement, and the Araya rims being used lately are only about 1mm in thickness. As a builder I don't like to see the spoke go beyond the maximum insertion in the spoke in the build, so if I am a bit short by 1mm on my initial measurement, the build usually comes out right for me. Smiles, MH
Thanks for beaming me aboard! I have not been using a lot of gusseted rims lately and forgot about the extra distance they propose for a good measurement, and the Araya rims being used lately are only about 1mm in thickness. As a builder I don't like to see the spoke go beyond the maximum insertion in the spoke in the build, so if I am a bit short by 1mm on my initial measurement, the build usually comes out right for me. Smiles, MH
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