GriddleCakes

I'm about to build my first set of wheels, with Shimano Deore M525 hubs and Velocity VXC 700c rims. I downloaded SpoCacl off of Sheldon Brown's site to get my spoke length, and since it didn't have my hubs I went to this Shimano page (last page, 3rd and 4th from bottom) for hub dimensions to enter into the SpoCalc spreadsheet.

And now I'm confused because the Shimano site lists the hub center to flange distances for the front hub as 31.7mm to the left flange and 21.1mm to the right. This is a disc brake hub, so the left flange is offset inward to allow for the brake rotor, so shouldn't the distance from the hub center to the left flange be less than to the right flange?

FBinNY 

Yes, it's likely a typo, though if the numbers are OK it doesn't matter if the right and left are reversed.

But you have the hubs, so why not measure yourself rather than rely on a spec you're not sure of. All you need is a 6" or 150mm ruler and a flat surface.

I assume that you know the width, so stand the locknut face of the axle on the edge of a table or book and measure up to the flange. Subtract from half the hub width. Flip and repeat and you'll have 2 reliable dimensions to use to calculate spoke length.

mrrabbit 

Typos and errors on two hubs are corrected in:

https://www.mrrabbit.net/wheelbyflemingapplications.php

Grab the spreadsheet...Shimano is probably the largest section...

Most Shimano hubs are measured to outside of flange in Shimano's doc - I correct to center of flange when I get 'em in hand...

=8-)

dscheidt

How much does that change calculated spoke lengths? A tenth of mm?

FBinNY 

Doesn't anyone actually measure stuff for themselves anymore?

Over the years I've found so many spec errors and variations, especially in rim measurements, that I measure everything for myself. The advantage of measuring for yourself is that you know and can trust the integrity of the data you input into the spoke calculator. If the spokes come out too long or short you know exactly whose fault it is.

dscheidt

I do. But I also like to buy all the parts at once, so if it's a rim or hub I don't have in my hands, I've either got to wait for the parts to show up, or trust the data I can find in spec sheets. (The shops around me charge a buck and a half a pop for decent spokes

mrrabbit 

.25mm of spoke length for each 1.0mm of flange movement maybe? Rim ERDs have much more impact.

FBinNY:

Rarely is it errors...but rather preferences:

1. DT rounds up or down their flange diameters. I have asked them personally not to do that. Manufacturers job is to publish AS-IS - it's the end users job to get the application right.

2. Campy and Shimano mostly measure to outside of flange. Mostly applies to Shimano because there are clearly two people editing their hub spec document.

3. Phil Wood increases flange diameter by about 1mm to accomodate "some unnamed party's" erroneous spoke calculation program that doesn't adjust for 2.4mm hole diameters. Once again, it is the manufacturer's job to publish specs AS-IS - it's the end users job to get the application right.

Like with people who publish ERD's without noting nipple and target - hub specs are so "massaged" or "preferentially biased" that you can't really trust the numbers. Once again it's back to square one - measure yourself.

...which is what I do as much as I can - and publish.

=8-)

=8-)

FBinNY 

Yes, it seems nobody is willing to simply measure anything, and publish the raw data anymore.

It's a bit ironic that you point this out with respect to hubs, since at other times you defend the practice of including a 4-6mm allowance for the heights of nipple heads in rim ERD data. (I'm not arguing the definition of the ERD here) With all the adjustments that makers make trying to anticipate how we'll use the information, or build the wheels the data becomes totally useless.

Imagine if makers of shoes decided to try to guess the thickness of the socks you will wear and factor that into shoe sizes.

I prefer that manufacturers stick to a semblance of the "four corners rule" and publish only actual, duplicatable dimensions of parts themselves - either by some standard method, ie. on hole centers for spoke hole diameter, or stating clearly how they measured - without trying to compensate for variables, like spoke or nipple selection. Real info, free of adjustments of any kind allow the user to make whatever adjustments he needs to to get reliable, repeatable results.

Unfortunately that isn't the case, so rather that try to guess what the maker has in mind, I'll continue to measure for myself.

mrrabbit 

FBinNY

1. Hubs - publish AS-IS
2. Rims - publish AS-IS

That's what manus should be doing - no massaging...I think we agree on that...

...however you seem to have forgotten that my point has always been that ERD is END-USER/BUILDER driven - it's not an as-is spec, whitepaper spec, etc. Never has been, never should be.

Nipple sizes, nipple threading, nipple profiles, spoke thread lengths, joints/seams, and builder preference DICTATE that ERD can never be an AS-IS spec. It's impossible...too many variables...

Hence my argument that IF you are going to publish ERDs, tell people your NIPPLE and AIM when publishing - or don't bother.

Damon Rinard (SpokeCalc) tells you he's aiming for the top of a 10mm standard profile nipple.
I tell folks (SpokeChart) that I'm aiming for the screwdriver flat of a 12mm standard profile nipple.

...and to be honest...it's not that hard to do. Seriously, if people are building wheels all the time - theyare also jotting down numbers all the time as well. It can be too much skin off their shoulders to grab the darn keyboard and mouse and take a minute.

=8-)

FBinNY 

I was careful to say that I wasn't debating the definition of ERD. Whatever anyone chooses to call it, I'm asking rim makers to publish the actual diameter at the nipple seat, ie, from the outside of the eyelet to the outside of the eyelet.

They could call it Actual Rim Diameter at nipple seat or ARD, or dimension X. I don't care what they call it, as long as it's a true measurable dimension exclusive of any adjustment or assumptions of any kind.

That will give me, or any other builder, the reliable required information so we can allow and adjust as we prefer for the nipples we use, and where we want the spokes to end.

Call me Joe Friday, "Just the facts, please"

dscheidt

Standard practice, actually. People buying running shoes are presumed to be wearing fairly thin athletic socks; people buying work boots are presumed to be wearing thicker socks.

EM42

++1


digital calipers only $15~20 at harborfreight tools good enough for bike work !!

a piece of string and tape measure will also work if $15 caliper is too much spending !