Yo!

Hey all,

I decided to go with Open Pros on WI hubs for a fixed gear build.

I used 605 for the ERD on the hoops and used 292mm length DT spokes (calculated using Bike Institute's calc) for the front wheel.

I'm lacing the front 3x, 32h. Hub is C to F 33mm and 65mm FD.

For some reason, after I finish the right side, the left side leading spokes are wanting to come off the flange at an extreme angle, so much so that it nearly crosses over the head of the trailing spoke, and are clearly too short.

This is the second time I've torn down and rebuilt, yet I'm still having trouble. Any suggestions?

Mr IGH

Sounds like the spokes are set in the hub incorrectly. I'd pull all the spokes from the left side and move them over one spoke hole, then try to lace the wheel again.

Yo!

I'll give this a shot; I had to relace the first time because the key spoke is the second hole over from the valve hole on the Open Pro, therefore the trailing spokes need to come to the one empty hole between the valve hole and the key spoke, but when I lace this way, I run into the aforementioned problem.

I'll just pull it all apart and try again I guess.

Mr IGH

This is what makes me think you're off by one hole. I assume the right side has the spokes all even, both sides of the right side hub flange's spokes are symeterical.

mrrabbit 

ERD of 605mm?

Whoah...

Usually it is 602mm min. / 603mm max.

I get 291mm for your specs...292mm should work - will hit top of nipples though but still work.

=8-)

Mr IGH

ERD of the Mavis Sport is 606, why do you think the Mavic Open is so low? The 319/319/719 is 600.

Yo!

I went w 605 bc it was my understanding that Mavic quotes spoke bed diameter as opposed to ERD, so I added 3mm to the advertised 602 ERD.

The first time I laced the wheel I was able to get all the way around 3x, but my valve hole ended up being in between two crossing spokes, so I tore down and redid it, only to run into the issue I'm having now. I probably am off a hole on the hub, but I just wanted some suggestions before I spent more time tearing down and rebuilding.

davidad

Do you have a photo we could see?

TallRider

I would also like to see

huh? where did all my text go?
I don't feel like re-writing it (or re-membering it) now that this thread has devolved into an Open Pro ERD thread.

mrrabbit 

Building my 1/2 dozenth Open Pro right now folks on a Phil Wood Single Single-Sided Track Rear...602mm it is...that'll result in the spokes finishing at or a hair above the screwdriver flat.

Trust me...605mm is pushing it...you are running the risk of running out of threads before reaching proper tension.

=8-)

Al1943

That's good information, thanks. I've built with Open Pros but can never find the ERD when I want it.

Al

operator

Yeah let's compare against a completely unrelated rim and guess the ERD. I just measured a 32h and a 36h open pro.

32h Open Pro = 602-603
36h Open Pro = 602-603

Once again reaffirming the fact that you should just measure everything yourself.

mrrabbit 

Someday I'm going to suffer Canadian and Oklahoman sales taxes just to share a soda with operator and Al1943 cause we seem to often be within a mm of each other on ERDs.

On rare occasions...an Open Pro will come in at 601mm...and sometimes 603mm. 602mm is my working average and usually what I get and stick with.

Anyone using 605mm and 606mm is asking for trouble cause if that nipple doesn't allow a couple threads past the top of the nipple - you are faciing a high risk of disassembly and substitution for shorter spokes.

=8-)

mrrabbit 

If you guys don't mind...I'll be happy to post my binder of ERDs for lotsa different rims...so you guys can print 'em out. I keep my calc papers when I can and rejot into my binder when not too busy. Reduces re-measuring which happens all too often out on the road.

=8-)

DMF 

That's the kinda thing ought to be in a sticky thread.

operator

Seems like it at first glance.

I guess we could give a range for ERD so people can do a quick sanity check. But as for using a number gleaned off the interwebz for erd...naw. I'm still going to measure most rims I build (we don't build too many wheels in a work month so getting doing the extra step isn't inefficient in terms of shop time. If this sticky were to happen i'd like to have a very large disclaimer at the bottom telling people to measure the ACTUAL rim they're using or gamble on the ERD matching the rim they're holding.

Also one other offtopic thing is that i'd love someone to make a digital ERD stick. Similar to a digital caliper but for quickly measuring ERd'S. The current $70MSRP sticks (seriously? sticks?) are ****ing annoying to use and it's not totally accurate either.

Al1943

I just took a look at the DT Swiss spoke length calculator, what I usually use. The help menu says that their ERD is measured at the nipple seats. And for Open Pro rims they use 605.
Not saying who's right or wrong.

Al

Soil_Sampler

+infinity!

make your own rim rods.
or
Sutherlands ERD tool: https://www.sutherlandsbicycle.com/rimdiametersystem/
or
bike-alog rimometer

Mr IGH

I use 602 for the 319, if you use 602 for the Open Pros you'll be too short. Wheel will look good, if that's what you're looking for...BTW, Mavic makes all those rims and publishes the dimensions, "unrelated" isn't really the correct word to use.

helicomatic

Perhaps you're one of those people who prefers to use spokes that come to the top of the slot in the nipple, rather than the bottom, and measure your ERD accordingly. This translates to about a 2.8mm increase, 605mm instead of 602.

If this is completely off the mark, I apologize, but it seems like the only reasonable explanation for everyone else using 602, and you (and DT) using 605. We build wheels to the bottom of the slot here at the shop.

Yo!

I tore down the wheel and relaced, and Mr. IGH was right, I was off on the left flange by a hole. Amateur.

Anyway, 605 ERD works, if not a tad long; the spokes poke up just slightly past the nipples when tensioned. I would say the best working ERD for Mavic OPs, a common ground, would be 603.

Mr IGH

Good point, thanks for taking the time to post. I am fixated on fully nipple penatration, I always prefer the spoke poking out slightly compared to having it slightly shorter than the screwdriver slot. You've explained the difference.

Don't ask me how I know this Glad you got it right!

TallRider

This just bears repeating

mrrabbit 

Phil Wood Single-Sided Track Rear
r=66.0
c_opp=44.0
c_drive=29.0

Mavic Open Pro 700c Double Eyelet
R=602.0mm

SL_opp = 292.00
SL_drive=290.50

Both sides run thru a Phil Wood Spoke machine - yes - I'll cut .5 mm increments.

Wheel is done with drive side carefully tensioned to 107-115 and dished. Result is such that the ends of the spokes both drive and opp side have finished exactly at the screwdriver flat.

Mind explaining how 602mm is too short? Just curious?

=8-)

Mr IGH

Using your numbers in the UBI calculator and 605, I get 293.5 on the 44mm side, I like full nipple penatration, you don't.