The_Joe

First time building a set of wheels. Tension seems high, spokes seem short, failure seems imminent.

Run down:
Miche Primato hubs
Ambrosio Excellight hubs
2.0/1.8 spokes
32 hole
3x
Rim brakes

I've been following along to Sheldon's site and Bike Gremlin's site. The wheel is true. Here is my concern:
There is still thread showing on the spokes.



I used the DT Swiss and Wheel builder calculators to get my.spoke length. Measurents were based on mfg respective websites as I did not already have the parts in my possession.

Following the base line for pitch on the Sheldon Brown site, I've got spokes that are 292mm and they all pluck to darn near an A note. Taking measurents on my cheapo imitation of a TM-1 I appear to be around 120kgf. Internet searches seem to say that's acceptable for the rims.

Are my spokes too short? Do I keep tensioning? I've only done the front wheel so far.

Thanks in advance.

Andrew R Stewart 

120kgf is getting mid to high tension for lightweight rims IMO. (and I have had a big name hub manufacturer tell me that 125kgf was too much tension for their 36 hole hubs...) The reason to do tensioning spokes during the build is for wheel stability/strength and not to "make up for less then best spoke lengths. For a rim braked and light rim front wheel I would tension to around 100=-.

Spoke length sure could be a tad (2 or 3mm?) longer but I doubt that there's failure coming in the short term. Remember (many) thousands of factory (and some hand built) wheels had had too short spokes with no problems due to that.

Different length calculators allow for spoke bed changes (eyelets or not, as example) and different rim manufactures measure to different outer points (like eyelets or extruded bed). Andy

mpetry912 

if that nipple shot is typical and you have a spoke tension of 120 KgF I think you might see some nipple failures.

as Andy said above probably 1 or 2mm short. see pic below.

What you might do is take your ball pein hammder and tap tap tap the spoke elbow at the hub flange (I always do this to seat the elbows in the hub) and completely strain relieve the whole wheel, then re-true. might get you a 1/4 turn more thread engagement per spoke.

Then ride it and see.

/markp

The_Joe

This picture is precisely what I was concerned about. I did do the ball pien thing already. I have no issue ordering new spokes and starting over if that's what it takes. With maybe a few exceptions I'd say every spoke/nipple is as shown in my picture.

KCT1986

Looking at your pictures, it seems that your spokes about 3mm short, if targeting between bottom of slot & top. Have you double checked that the lacing is correct? If you followed Sheldon's procedure, the lacing should be quite straightforward. An early sign of a problem should have been seen when you started to get to a baseline of nipple position. Most do this step by setting all nipples so a consistent # of treads remain visible (normally just when the last tread goes into the nipple).

Looked at the specs of the hub & rim, and would guess that the rim's ERD is wrong, or the spoke hole circle is mistaken. The hub's offset has a lesser effect on the spoke calculation.

There may have been a change made to the cup used to connect the double walled rim bed. Also, hard to say what assumption was made in 'spoke end' position when their measurement was taken.

It is always advisable to take actual measurements of ERD, whenever feasible. Procedure available online and will allow you to know exactly where the 'target' is for your calculation and whether to round up or down.

The_Joe

Thank you. The lacing is correct. I was head scratching for a bit because things did get wonky at first. The guys over at C&V helped me with that one.

I started the process by getting all of the spokes to the same length as you suggest. That's when I noticed how short things seemed. With about a thread showing my tension seemed very high.

Since I still have another rim and hub to build I think I'll keep the front as is for now. I'll remeasure and get appropriate spokes for the rear. Then I'll be prepared.to rebuild the front of things go south.

grumpus

Short enough to worry about. Don't try to stretch them, just put it down to experience and buy some longer spokes.

The_Joe

I just used the Park tool method to measure my ERD. 2 spokes of a known length and calipers to measure the gap. It brought me to 603mm which unfortunately is much larger than the 598mm ERD Ambrosio cites on the their website. I guess I'm buying longer spokes.

Thanks to all for your advice and assistance.

KCT1986

Yes, about what was expected based on the pics (the top of the wrench flat is quite close to the rivet). Some change must have been made, possibly to the 'cup' or the rivet for the spoke reinforcement. Or their measurement was just to the rim without taking into account the 2-3mm that the spokes protrudes into the nipple.

If you decide to not respoke the front, back off the tension a bit. The front can usually withstand lower tension since it has no dish. In the short term, brass nipples shouldn't fail even of not penetrated to the head.

Hooligans

That's interesting because I had the same experience using the Park Tool method vs. the label on the rim itself (Sun Rhynolite XL). I ordered spokes based on the larger number from my Park method measurements... we'll see.

Duragrouch

Fantastic rims, I love double socketed, wear like iron, wish I could find in 406, in fact I think they are becoming scarce in 700c.

My concern with the above pic is what looks like either a raised rib or valley under the socket lip, not sure about the pic angle but I don't think it's the lower corner between the sidewall and the outer wall that the socket sits on. Don't see same feature on the other side, although the sockets may be alternating left and right and it's just the camera angle. But something looks off about that. Unless there is a rib on each side that I can't see, and the purpose of the rib is to cock the socket toward the side that the spoke is aiming.

Bill Kapaun

Will they lace up 2 cross?

The_Joe

Way too long for a 2x unfortunately. Not to worry. I'll learn from the mistake and it'll give me more practice.

The_Joe

The rib is just the one side. Not sure what it's purpose is but it's on both rims so not a an issue as far as defects go. The eyelets do alternate. I haven't looked closely enough to try and figure out the purpose of the rib.

Duragrouch

Rib only one side, huh, that rules out it being designed to cock the alternating eyelets. I would think it might be for positioning to drill the holes, but you said the eyelets alternate laterally, so again, doesn't make sense. Let us know if you find out.

Are those rims current production, or NOS (New Old Stock)?

FBinNY 

Pardon if this has been said.

The reason your spokes came up short is because of the sloppy definition of ERD.

As used by most spoke calculators, it means the diameter where you hope the spokes to end, ie. just shy of the tops of the nipples


When published as a spec. by (some) rim makers, it's the actual diameter where spokes sit. Rim makers do this because a spec. must be measurable, and they don't know what nipples a builder might plan on, or where he prefers spokes to end, so they correctly publish what they KNOW.

That leaves a roughly 4mm per side discrepancy reflecting the heads of nipples.

This is why I insist that people measure everything for themselves. Otherwise they have to play the Newlywed Game, and guess what other party thinks you are thinking.

There's no way around it ----- either accept what you have, and caklbit a day, or buy spokes 4mm longer and start anew. Next time MEASURE.

Bikerepairing

But I have a question: what on earth made you decide to build your own wheels? I can only think of the fact that you like the process and want to do all this work just for the experience?
Anyways, lots of luck! I hope you get it right!

fishboat

+1, my same experience. I built up a set of H Plus Son Archetypes. I ran across some mention on the web of H Plus Son's "error" in reporting their ERD. I measured the expected(based on parts used) ERD myself and did indeed get a different value. I ordered spokes based on that measurement and they fit perfectly.

fishboat

A good portion of your conclusion that the spokes are at the correct tension is based on a very suspect tool. With due respect..garbage in garbage out (as they say).

https://www.bikeforums.net/bicycle-m...on-meters.html

Note specifically the charts reporting the cheap tensiometer indicated values vs the much better tensiometer's remeasured closer-to-reality values.

There was a recent thread discussing a wheel build that may be of some use..https://www.bikeforums.net/bicycle-m...ion-meter.html

ScottCommutes

Congratulations, you built your first wheel. It's not perfect, but it will work. You also learned some lessons. As others have said, you could ride as is, or redo it with longer spokes. Nobody will ever know because your error is tucked inside the rim (no "apprentice marks").

Changing the musical tone of a spoke (once you get to that level), is +/- about one revolution of the nipple. You obviously are short by several full turns and should not try to fix this with tensioning. I would call the wheel finished.

Regarding tension tools, remember that for many years they weren't used at all. Double check your tool in every way you can think of. It should be able to repeat a reading, even if the reading is bad, so compare your spokes to the spokes on a known good wheel and see what that looks like. Also a good idea to continue to use the low-tech methods of listening to notes and squeezing pairs of spokes.

Smart idea doing the front first. Good luck on the rear.

Bill Kapaun

What do you think this forum is about?

The_Joe

I'll try and respond the best I can without needing to quote everyone. Maybe you'll all see it.

These are new production rims.

I could not measure the rim as I didn't have it in hand yet. Lesson learned. I remeasured and have ordered longer spokes.

The tension meter reading high is a lesser issue in this instance. Yes, it's partly where I'm basing my numerical value of tension but I'm just using it as another frame of reference. I'll check out your link. What I should have also mentioned is that any further tensioning results in significant noise, torsion, and effort. Squeezing the spokes I can easily tell that they're much tighter than any of my other wheels.

I'm building wheels because why not! This is a long term project and I've got to wait for the frame to be painted anyway. The other reason is because there were no pre built wheels that fit what I wanted.

FBinNY 

There's never a need to justify or explain a decision like this. You opted to build wheels because you wanted to. End of story.

As for relying on specs. and/or buying without measuring, that will happen, and we all need to sometimes.

You can't do much about buying the wrong spokes, except return them if allowed, but you can save yourself wasted time.

First, measure the rims upon receipt, and confirm the ERD, and spoke calculation before building.

You can also trial the length using 2 spokes going to opposite sides of the rim, and corresponding holes near each other in the hub. To clarify, spokes to 12&6 on the rim and 2&4 on the hub. Tighten nipples to desired height, and the hub should cause some tension when pushed sideways to where it will end up.

This takes a minute or two, but can save much more.

Bike Gremlin

I would recommend investing some $10 into this book:
https://www.wheelpro.co.uk/wheelbuilding/book.php
That is the simplest way to learn how to build wheels.

If you wish to learn why, I suggest you read the Jobst Brandt's "The Bicycle Wheel".

The book's author, Roger Musson, made a spoke length calculator that has worked very well for me with both bicycle and motorcycle wheel building (with some tweaks for the latter as the calc. doesn't give any support for 3+ mm thick spokes).
Unfortunately, the calculator is no longer supported for those who haven't paid for the book.

With the spokes being too short, the nipple head might break off with heavy/strong riders even when strong rims are used. Case in point:
https://bike.bikegremlin.com/8431/custom-wheel/#4

One of the most common mistakes when calculating spoke length is relying on the manufacturer's ERD data.
The data provided for the hubs is less critical and more often accurate, but the ERD measuring methods can affect the results (and if the calculator you use doesn't use the same method, you could run into problems, as you have).

What FBinNY explained is a good, reliable way of measuring the ERD.
Longer explanation with pictures:
https://bike.bikegremlin.com/9266/ef...-rim-diameter/

Still, I think investing the money and time into the above-mentioned book(s) will probably help more than a thousand forum questions and replies.
I can not recommend those enough.

Relja

FBinNY 

Thank you for clearly, though possibly unintentionally, showing the issue with ERD data.

In your linked post are images showing ERD for a single wall and 2 double wall rims. They're inconsistent because the first has ERD to the nipple seat, and the other two to the nipple top.

Both are "correct" depending on how you define ERD, but I suggest you settle on one and synchronize the graphics accordingly.