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HOW TO - calculate the ERD of any hoop & calculate spoke length  RSS Feed

#1 2016-01-09 7:15am

caleb_k31
BMXer 4 Life
From: Milwaukee, WI
Registered: 2006-04-07
Posts: 6884
Bikes: 15

HOW TO - calculate the ERD of any hoop & calculate spoke length

I receive several PM's per week with spoke length questions. Responding to everyone is pretty time consuming because I have to go check several pages and copy links with info and send them to everyone. I decided to make a video and post this thread so we can get all this info in one place.


This video will show you how to easily calculate the ERD
https://www.youtube.com/watch?v=a3RIbCj … e=youtu.be

hub measuring video
https://www.youtube.com/watch?v=Ikw9WzN … e=youtu.be

spoke calculator
http://www.prowheelbuilder.com/spokelengthcalculator/

how to build a wheel for the do it yourselfers
http://bmxmuseum.com/forums/viewtopic.p … 11&p=1





if you use a spoke ruler this is what it will measure.

http://i144.photobucket.com/albums/r183/caleb_K21/bike%20parts%20referance/Spoke%20Length_zpsw7pmwlpj.jpg






this is what the ERD measures-


http://i144.photobucket.com/albums/r183/caleb_K21/WHEELS/SpokeCalc_ERD_zps73mxldub.gif


Depending who you ask there is 3 ways to measure ERD-

1- the top of the nipple to the top of the nipple. (you can minus 4mm and get the same measurement as #3)
2- the bottom of the screwdriver slot in the nipple to the same point on the other side. (you can minus 2mm and get the same measurement as #3)
3- the inside of the hoop where the bottom of the nipple head sits.

example diagram -  see how the nipple head adds 4mm overall counting the opposite side (2mm per side).

http://i144.photobucket.com/albums/r183/caleb_K21/WHEELS/840693d1382379308-light-bicycle-carbon-rims-width-erd_zpswp6one6a.jpg

all of the ERD's I have listed were measured to the bottom of the screwdriver slot. I have had very few issues using the Southerland measuring kit witch give you the measurement, however since I can cut spokes right at home it was no big deal, for most people you may be better off not using that method just to be safe, or you may end up trimming some of the spoke ends with a dremmel tool once you have the wheel built. To get the true hoop ERD minus 3mm from all ERD the measurements below.


ALL 20" hoops
ACS Z - 395
Arays 7L - 398
Araya 7X - 394
RL Edge - 401
Peregrine super pro (HP 48's, also the peregrine with the gold eyelits) 394
Ukai 7C - 393

ALL 24" hoops
UKAI 7C, HE/LA - 496
Pro Class - 495
Araya 7X - 492


ALL 26" hoops

pro class - 547
knoch off pro class (porkchop?) 545
Ukai 7C - 544
Ukai Speedline - 546
Sun rhino lite - 550
Araya 7X - 546





here is some more helpful info if you don't have the means to measure and you still want to build your own wheels. if none of this works feel free to contact me and I can take care of building them for you.






sometimes you can get away with spoke a few millimeters short or a few millimeters long and be just fine. There are way to many variables for me to tell you spoke size without measuring. you can use the GENERIC LENGTH that most people use when they don't know the exact length to the millimeter.




these DO NOT work for all hubs/hoops, your best off having them measured properly. if you choose to use a GENERIC LENGTH that's up to you. here are some GENERIC LENGTHS that I have on hand and I will be working on more in the future. using this method your best off with a 16mm long nipple just incase your spoke are a hair short the long nipple will help bridge that gap. if your spoke is a hair long and sticks out the back of the nipple you must grind it off with a dermal tool.




ALL 4X pattern, 36 spoke wheels
20" hoop - low flange hub (or high flange) - 194mm
24" hoop - low flange hub (or high flange)- 244mm
26" hoop - low flange hub (or high flange)- 269mm


ALL 3X pattern, 36 spoke wheels
20" hoop - low flange hub - 185mm
20" hoop - high flange hub - 183mm
24" hoop - low flange hub - 235mm
24" hoop - high flange hub - 232mm
26" hoop - low flange hub - 260mm
26" hoop - high flange hub - 257mm

ALL 4X patters, 48 spoke wheels
20" hoop - low flange hub - 185mm
20" hoop - high flange hub - 183mm

ALL 3X pattern 48 spoke wheels
20" hoop - low flange hub - 179mm
20" hoop -high flange hub - 175mm






this is a nifty tool my friend found in an old closed down bike shop, it is for pulling flat spots out of the rims. I used it twice already and it works well.


http://i144.photobucket.com/albums/r183/caleb_K21/bike%20parts%20referance/068_zpshofvx5mj.jpg

Last edited by caleb_k31 (2016-08-20 3:49pm)


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epoch headset, freestyle vs. race - http://bmxmuseum.com/forums/viewtopic.p … 7#p4233077

All the hub/hoop measuring info you will need along with spoke calculation info http://bmxmuseum.com/forums/viewtopic.p … 9#p5435389

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#2 2016-01-09 7:56am

caleb_k31
BMXer 4 Life
From: Milwaukee, WI
Registered: 2006-04-07
Posts: 6884
Bikes: 15

Re: HOW TO - calculate the ERD of any hoop & calculate spoke length

this pic is provided from the link someone posted below.


so here you can see that the angle of the spoke on a 4x pattern makes the flange diameter irrelevant in the case of regular high and low flange hubs (any hub with an abnormally large flange would not be included in this). even though when measuring everything out the spoke calculator may tell you 195-197 which may or may not work in some cases. like the guy in that other thread said he does not believe spoke calculators to always be accurate and after using them many times and building hundreds of wheel I would tend to agree with him on that. 

so the center circle can represent a low flange hub, and the slightly larger circle can be a high flange hub. the spokes are at the same angle so moving the butt end over a little does not change the length.


when you get into 3x patterns then you will have a difference of 2 or 3mm in most cases due to the angle of the spokes.

I personally don't like a 4x pattern on a 36 spoke high flange hub due to the spokes angling over the outside of the flange so much.

http://i144.photobucket.com/albums/r183/caleb_K21/WHEELS/Spokes4X_zps8rw1mym0.jpg

Last edited by caleb_k31 (2016-01-13 5:37pm)


WILL NOT DEAL WITH LIST 619-bmx, Boyd, NickWG19, quadsticher, Djrothus, cgeorge715, bob70, sharkbite, Luke Sears ebay name bmxbrigade.

GT fork stander spring install - http://bmxmuseum.com/forums/viewtopic.php?id=426565
PFT restoration thread - http://bmxmuseum.com/forums/viewtopic.p … 50&p=1
epoch headset, freestyle vs. race - http://bmxmuseum.com/forums/viewtopic.p … 7#p4233077

All the hub/hoop measuring info you will need along with spoke calculation info http://bmxmuseum.com/forums/viewtopic.p … 9#p5435389

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#3 2016-01-09 7:57am

caleb_k31
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From: Milwaukee, WI
Registered: 2006-04-07
Posts: 6884
Bikes: 15

Re: HOW TO - calculate the ERD of any hoop & calculate spoke length

hoops with eyelits are better for certain hubs or lacing patterns, like superlace hubs, for example, . the spokes can angle much more on a hoop with an eyelit.



http://i1243.photobucket.com/albums/gg548/caleb_k31/others%20restorations/001_zpscff96a2c.jpg
http://i1243.photobucket.com/albums/gg548/caleb_k31/others%20restorations/002_zps942bb711.jpg

if the nipple has no eyelit to rest in it can end up looking like this with these hoops, because the spokes angle so much. 

http://i1243.photobucket.com/albums/gg548/caleb_k31/others%20restorations/085_zpsc9c6a81f.jpg

look close at this 1990 GT catalog, notice the're the same.
http://i1243.photobucket.com/albums/gg548/caleb_k31/others%20restorations/aggressor_non_team_zpsa5a386bb.jpg

Last edited by caleb_k31 (2016-04-13 3:52am)


WILL NOT DEAL WITH LIST 619-bmx, Boyd, NickWG19, quadsticher, Djrothus, cgeorge715, bob70, sharkbite, Luke Sears ebay name bmxbrigade.

GT fork stander spring install - http://bmxmuseum.com/forums/viewtopic.php?id=426565
PFT restoration thread - http://bmxmuseum.com/forums/viewtopic.p … 50&p=1
epoch headset, freestyle vs. race - http://bmxmuseum.com/forums/viewtopic.p … 7#p4233077

All the hub/hoop measuring info you will need along with spoke calculation info http://bmxmuseum.com/forums/viewtopic.p … 9#p5435389

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#4 2016-01-09 9:10am

rcsnipe2000
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From: La Porte ,TX
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Re: HOW TO - calculate the ERD of any hoop & calculate spoke length

good job brotha! nicely layed out. someone needed to do this for sure!!!

thanks,
rc


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#5 2016-01-10 7:38am

Johnnny
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Re: HOW TO - calculate the ERD of any hoop & calculate spoke length

Great thread. I stickied it. cool


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#6 2016-01-10 12:24pm

RACEINC43
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From: Washington Township, MI
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Posts: 253

Re: HOW TO - calculate the ERD of any hoop & calculate spoke length

X


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#7 2016-01-10 3:44pm

belloq
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From: NY
Registered: 2009-05-21
Posts: 101

Re: HOW TO - calculate the ERD of any hoop & calculate spoke length

Was just looking for this info. Thanks.

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#8 2016-01-10 6:56pm

Erikv
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From: Stuart, Florida
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Re: HOW TO - calculate the ERD of any hoop & calculate spoke length

Great YouTube video Caleb

I see on the cross 4 lacing the spoke length is the same for both high & low flange hubs?
I always had the impression high flange hubs ran a bit shorter spokes?

Last edited by Erikv (2016-01-10 7:00pm)

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#9 2016-01-10 7:16pm

caleb_k31
BMXer 4 Life
From: Milwaukee, WI
Registered: 2006-04-07
Posts: 6884
Bikes: 15

Re: HOW TO - calculate the ERD of any hoop & calculate spoke length

On a 4 cross pattern the spokes angle so much they are pretty parallel so changing the flange diameter does not change the spoke length.

I will try to get a detailed picture or another video and show an example. 


In my video I measure the outside diameter of the flanges, some people measure the distance from the center of the spoke holes instead. In most cases both ways give you the same length.

With a 3X pattern these thing may affect the length a little bit and I have noticed that sometimes the spoke Calculator  does go a tad high so when measuring certain parts I sometimes drop 1 or 2 mm off the length the calculator gives me.  If your using a 16mm nipple you should always be good even if you spoke is a hair short  you would never know. But using a 12mm nipples you have to be pretty precise because there is not much room for play.

I'll make another video with more info soon.

Last edited by caleb_k31 (2016-01-11 5:56pm)


WILL NOT DEAL WITH LIST 619-bmx, Boyd, NickWG19, quadsticher, Djrothus, cgeorge715, bob70, sharkbite, Luke Sears ebay name bmxbrigade.

GT fork stander spring install - http://bmxmuseum.com/forums/viewtopic.php?id=426565
PFT restoration thread - http://bmxmuseum.com/forums/viewtopic.p … 50&p=1
epoch headset, freestyle vs. race - http://bmxmuseum.com/forums/viewtopic.p … 7#p4233077

All the hub/hoop measuring info you will need along with spoke calculation info http://bmxmuseum.com/forums/viewtopic.p … 9#p5435389

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#10 2016-01-11 9:12am

manikinxvx
Museum Newbie
From: SW Wisconsin
Registered: 2015-12-01
Posts: 16
Bikes: 2

Re: HOW TO - calculate the ERD of any hoop & calculate spoke length

Thank you *very much* for this video! cool

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#11 2016-01-11 9:49am

troynlori
Moderator"Pedal Peddler"
From: Virginia Beach, VA
Registered: 2009-11-22
Posts: 15202
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For Sale: 119

Re: HOW TO - calculate the ERD of any hoop & calculate spoke length


Hutch Fun Facts: All main line Hutch's with digits only S/N (no letters or baseballs) on the rear drop outs were US made and had their dropouts stamped between late '83 and '86.  Obviously the frame manufacture would occur slightly after that, even if they just threw 'em in a bucket randomly.  There is an obvious date code in that the first 2 digits seem to be the month and the 3rd digit is pretty obviously the last digit of the year running from '83-'86.

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#12 2016-01-21 1:35am

thand72
I'm all out of Auburn Stuff
From: Ontario
Registered: 2011-02-26
Posts: 1608
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Re: HOW TO - calculate the ERD of any hoop & calculate spoke length

Awesome info. Thank you for sharing.


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#13 2016-01-21 12:24pm

tim1218
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Re: HOW TO - calculate the ERD of any hoop & calculate spoke length

Erikv wrote:

Great YouTube video Caleb

I see on the cross 4 lacing the spoke length is the same for both high & low flange hubs?
I always had the impression high flange hubs ran a bit shorter spokes?

Link to video?

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#14 2016-01-21 1:46pm

caleb_k31
BMXer 4 Life
From: Milwaukee, WI
Registered: 2006-04-07
Posts: 6884
Bikes: 15

Re: HOW TO - calculate the ERD of any hoop & calculate spoke length

Tim1218  see the illustration  in post #2


WILL NOT DEAL WITH LIST 619-bmx, Boyd, NickWG19, quadsticher, Djrothus, cgeorge715, bob70, sharkbite, Luke Sears ebay name bmxbrigade.

GT fork stander spring install - http://bmxmuseum.com/forums/viewtopic.php?id=426565
PFT restoration thread - http://bmxmuseum.com/forums/viewtopic.p … 50&p=1
epoch headset, freestyle vs. race - http://bmxmuseum.com/forums/viewtopic.p … 7#p4233077

All the hub/hoop measuring info you will need along with spoke calculation info http://bmxmuseum.com/forums/viewtopic.p … 9#p5435389

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#15 2016-05-10 9:31am

dedmann
Pro Member"is Air-Cooled"
From: the Zone
Registered: 2010-03-30
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Re: HOW TO - calculate the ERD of any hoop & calculate spoke length

i have to suggest a correction:
the ERD (Effective Rim Diameter) is the value in mm for the seating area under spoke nipple; not above. the nipple could be any number of demensions. the rim never changes. you can measure the inside of rim and add thickness of the rim seating area twice to obtain ERD. I would like to add that there is no difference in short or long nipples threaded section. If you look into a short nipple and compare it to a long nipple; the non threaded section of nipple will be longer. thats all; same amount of threading. smile

http://fcdn.mtbr.com/attachments/wheels-tires/840693d1382379308-light-bicycle-carbon-rims-width-erd.jpg


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#16 2016-05-12 9:10am

caleb_k31
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From: Milwaukee, WI
Registered: 2006-04-07
Posts: 6884
Bikes: 15

Re: HOW TO - calculate the ERD of any hoop & calculate spoke length

That's good info. I think Southerland said it's the distance from the bottom of the screwdriver slot in the nipple.   

For most people I would actually recommend using the distance from the inside of the hoop like you said it may prevent any chance of the spokes being too long. 

I will update the upper post and include your picture and info. Thanks


WILL NOT DEAL WITH LIST 619-bmx, Boyd, NickWG19, quadsticher, Djrothus, cgeorge715, bob70, sharkbite, Luke Sears ebay name bmxbrigade.

GT fork stander spring install - http://bmxmuseum.com/forums/viewtopic.php?id=426565
PFT restoration thread - http://bmxmuseum.com/forums/viewtopic.p … 50&p=1
epoch headset, freestyle vs. race - http://bmxmuseum.com/forums/viewtopic.p … 7#p4233077

All the hub/hoop measuring info you will need along with spoke calculation info http://bmxmuseum.com/forums/viewtopic.p … 9#p5435389

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#17 2016-05-17 4:11pm

markmc97225
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From: Beaverton, OR
Registered: 2008-05-29
Posts: 4166
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Re: HOW TO - calculate the ERD of any hoop & calculate spoke length

I'd agree the ERD is the RIM diameter, so nothing involving the nipple in the measurement at all. But, I do think that there is a needed safety margin provided by the head, which allows for 1-2 mm without really causing worry. For a hardcore rider/racer, even that 1mm could be a big deal, but, for collectors and stuff, likely 1mm of ERD isn't likely going to cause serious issues.


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#18 2016-07-23 10:36am

Ripperdawg13m
Pro Member
From: Mpls, MN
Registered: 2013-02-19
Posts: 1955
Bikes: 8

Re: HOW TO - calculate the ERD of any hoop & calculate spoke length

Great info !!!

Nice to have this on hand smile


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#19 2016-09-09 12:21pm

sdunlimited
Member
Registered: 2007-10-06
Posts: 68
Bikes: 5

Re: HOW TO - calculate the ERD of any hoop & calculate spoke length

Hi Guys - lots of great info here although it's got my head spinning and dizzy! 
I was planning to try and re-lace some Araya's I have with Haro Mega Hubs.  The spokes are all rusted out.  I have never done this before. 

After watching several videos, reading through threads here and elsewhere, I'm trying to simplify the process to get to an "actionable" stage where I'm hands on. 

Troynlori linked a thread above where someone said that they use 194mm spokes on all 20" 4x lacings and 184 on all 20" 3x lacings.  That sounded like simple info I can work with if accurate big_smile

Now I'm having a real noob problem - I'm trying to determine if these wheels are 4x or 3x.  As far as I can tell it's 3x, but could someone please confirm for me?

Here's are a few pics:
http://i239.photobucket.com/albums/ff122/sdunlimited/Bicycles/2A167687-1E96-4E2A-85E7-C98B23612196.jpg

http://i239.photobucket.com/albums/ff122/sdunlimited/Bicycles/EA083CD7-A77B-4A25-9BB1-181F2380CDA6.jpg

http://i239.photobucket.com/albums/ff122/sdunlimited/Bicycles/150C7EBE-4DDC-4663-8C69-3CDB70C4C674.jpg

Thanks a lot for any guidance, it is appreciated!

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#20 2016-09-14 7:57pm

surferkain
Pro MemberA.U.O.K.
Registered: 2008-03-02
Posts: 807
Bikes: 5

Re: HOW TO - calculate the ERD of any hoop & calculate spoke length

look like 4 times.


This is my bike, there are others like it but this one is mine.

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#21 2016-09-15 4:03am

troynlori
Moderator"Pedal Peddler"
From: Virginia Beach, VA
Registered: 2009-11-22
Posts: 15202
Bikes: 11
For Sale: 119

Re: HOW TO - calculate the ERD of any hoop & calculate spoke length

3X


Hutch Fun Facts: All main line Hutch's with digits only S/N (no letters or baseballs) on the rear drop outs were US made and had their dropouts stamped between late '83 and '86.  Obviously the frame manufacture would occur slightly after that, even if they just threw 'em in a bucket randomly.  There is an obvious date code in that the first 2 digits seem to be the month and the 3rd digit is pretty obviously the last digit of the year running from '83-'86.

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#22 2016-09-15 5:00am

sdunlimited
Member
Registered: 2007-10-06
Posts: 68
Bikes: 5

Re: HOW TO - calculate the ERD of any hoop & calculate spoke length

Thank you. I spoke with my LBS who walked me through some basics and confirmed the 3x lacing. They also quoted $85 per wheel to re-lace. $1 per spoke plus 2-3 days to complete. That sounded longer and more expensive than I've read about but I've never done it and can't say from experience. They said it would be a "difficult rim to do" but didn't explain why.

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#23 2016-09-18 10:12am

caleb_k31
BMXer 4 Life
From: Milwaukee, WI
Registered: 2006-04-07
Posts: 6884
Bikes: 15

Re: HOW TO - calculate the ERD of any hoop & calculate spoke length

Sdunlimited, wow that's a total rip off price from your local shop.  PM sent


WILL NOT DEAL WITH LIST 619-bmx, Boyd, NickWG19, quadsticher, Djrothus, cgeorge715, bob70, sharkbite, Luke Sears ebay name bmxbrigade.

GT fork stander spring install - http://bmxmuseum.com/forums/viewtopic.php?id=426565
PFT restoration thread - http://bmxmuseum.com/forums/viewtopic.p … 50&p=1
epoch headset, freestyle vs. race - http://bmxmuseum.com/forums/viewtopic.p … 7#p4233077

All the hub/hoop measuring info you will need along with spoke calculation info http://bmxmuseum.com/forums/viewtopic.p … 9#p5435389

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#24 2016-09-18 6:04pm

sdunlimited
Member
Registered: 2007-10-06
Posts: 68
Bikes: 5

Re: HOW TO - calculate the ERD of any hoop & calculate spoke length

caleb_k31 wrote:

Sdunlimited, wow that's a total rip off price from your local shop.  PM sent

Thanks for taking the time to connect - I appreciate it.

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#25 2017-03-25 6:34am

powersbikeshop
Pro Member
From: Richmond, VA
Registered: 2007-08-12
Posts: 1013
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Re: HOW TO - calculate the ERD of any hoop & calculate spoke length

ALL 3X pattern, 36 spoke wheels
20" hoop - low flange hub - 185mm
20" hoop - high flange hub - 183mm
24" hoop - low flange hub - 235mm
24" hoop - high flange hub - 232mm

THIS INFO IS WRONG


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