nazcalines

Great looking bike and refreshed wheelset! I built a wheelset around the Brevets last year and also wanted to go with something light, while keeping it mostly passable as C&V, and with quiet hub ratcheting. Unfortunately there were no $40 (!) 7700 hub sets around and I compromised with a Bitex raf12 front and Tiagra r400 rear. 28h front + rear with dt revs got the weight down to ~1650g without skewers in 650b size.

RiddleOfSteel

Thanks! 1650g out of a 650B build is still nice and light. Those wheels should spin up real quickly.

RiddleOfSteel

Ooohhhhhh we're baaaaack!!!

Unfortunately.

After four or five post-build truings, the front wheel has refused to behave, and it is time to look at what I believe are the culprits: the spokes. I have been living with Pulsing Under Braking Central for this entire TB14 era and it has been driving me up the wall. I have never known any slightly out-of-true rim to kick the way it has under essentially any braking effort. Sure, I'm no wheel-building pro, but I've done a few, can follow directions, and am pretty detail oriented and sensitive to things.

The spokes are too short, by more than I would care to live with, and they didn't seem to respond well to being reworked, try as did to get them to cooperate. So I told myself I can totally live with mismatching spokes, especially if the new ones are likely lighter as they are a thinner gauge (2.0-1.5-2.0 vs 2.0-1.8-2.0), the correct length (so no failure, kinda important...), and allow me to flipping ride my best-she's-ever-been Paramount! And I did manage a 22-ish mile ride with a friend a few days ago and the bike loved it. It bombed down huge descents--bumpy ones even--and didn't have an issue. Massively stable. Climbing was great, especially out of the saddle. And once you were rolling, the wheels just wanted to keep rolling forever. It was fantastic, and my left knee played along for quite some time.

Anyways, the spokes have arrived. DT Swiss Revolutions in the correct length. Time to see if I can line up the Dura-Ace + rim valve hole AND have parallel spokes at the valve hole, too. And yes, I hope the impressions in the hub flange left by the spokes over time also lines up (inside/outside). We'll see.

Classtime 

If the impressions left in the flanges do end up going the wrong way, maybe that is ok. 20 thousand miles from now, the hubs will need new rims, and you can go either way without consequence. In my builds, I always twist the hubs backwards after all the heads out spokes are in. And sometimes, with used hubs, and the impressions going the wrong way, I wonder if I switched the pulling with the pushing spokes, that could be avoided.

RiddleOfSteel

Numbers:

DT Swiss Revolution - 2.0-1.5-2.0 - 298mm length - 32 spoke total weight: 150g (4.7g per spoke)

DT Swiss silver brass spoke nipples - 12mm length - 32 total: 31g

Shimano Dura-Ace 7400 front hub - OB (Feb. 1990) - no skewer: 146g

Old double-butted spokes - 2.0-1.8-2.0 - "298mm" length - 32 spoke total weight: 195g

RiddleOfSteel

Great to know. Thanks!

mech986 

I was under the impression that once laced, the spokes should always go the same direction when relacing a hub. Otherwise, you have stress risers in different places that could lead to failures of the hub flange or holes.

RiddleOfSteel

Well the "calculated" spoke length (via app, confirmed by a respected friend) and my measure/add/substract are presently wrong....

Spocalc give 298.7mm. I measured 288mm + 12mm for the full length of the nipple, -1 for spoke stretch and got 299. Confirmation with said friend ends in going for 298mm. We haven't been wrong before, so I am at peace with the decision.

Old and new spokes are both 298mm. Stretched out, the new ones go only as deep as the old ones. I barely got the threads eclipsed by the nipple and I'm at 100 Kgf more or less. Spoke tone is where it is supposed to be, and I am just as "shy" of the nipple slot as before. I'm pretty mad right now. Either the ERD of these TB14s is grossly incorrect, I can't measure to save my life, or the app is incorrect. Like before, I need another 1.5mm to come up to the slot of the nipple, and another 2mm to be fully flush with the top of the head of the nipple. Unbelievable.

At this point, the nice and pretty new spokes are mine. I laced them perfectly, Dura-Ace-to-valve-hole. But from what I understand about wheel building, and the whole point of getting new spokes, is that I need 300-301mm spokes now. I mean, well, now I know, right?

Let me know if my new math here is correct. I just want to ride the bike without trouble and I'm currently going nowhere after spending time and good money. I just want to get back to this:

ThermionicScott 

That sucks, but you're probably fine if the spokes thread far enough into the (12mm brass) nipples to hide the threads. If you were running aluminum nipples, it might be a cause for concern...

Retrogression measures the TB14 ERD at 611.5mm instead of the 610mm spec, so maybe that's why you didn't achieve as much extra engagement as you were hoping for.

BTW, when calculating spoke lengths, I only count on the rear DS ones to stretch appreciably, so I round them down. Otherwise I round to the closest available spoke length.

And I have no idea how short spokes would cause the wheel to pulse under braking. Sometimes welded and machined rim joints are not perfectly aligned beforehand, and require the spoke tensions in that area to be a little unbalanced in order for the wheel to run true. Something to check out.

RiddleOfSteel

I remember seeing Retrogression (whom I bought the rims from) list the ERD at that 611.5mm number. I assumed, fairly logically in my mind, that whether it be 610mm or 611.5mm, it was still less than the 613mm of the Mavic MA2. Maybe we're dealing with two specifications that are just a little bit off enough to make it noticeably off.

Like you, I've never come across pulsing brakes. And 3 out of 4 TB14s I've built up have been completely fine. I even tagged the pulsing area with tape so that when it went out of true again, I'd be able to tell if it was a group of problematic spokes, or if the rim was bad there. No luck. The pulsing kept changing locations.

I will say I did notice some larger than perhaps necessary tension differences when truing, as I did my best to not only true the wheel, but to balance the tension between sides as best as possible. These new spokes, at initial tensioning, are quite even. And upon doing some de-tensioning (or evening out tension), there was a hint of give with these new spokes as opposed to essentially no give with the old spokes. I know it sounds like I'm grasping at straws a bit, but I'm putting any and all observations out there to see what could be different, if anything.

At this point, they're laced up. I'll finish in the morning, put the rim tape, tube and tire on, mount it on the bike, and see what happens. The rims (when I initially built and trued them) spin nicely when true, and I've been able to dial them in pretty darn well. When they return post-riding, there is definite run-out. Hopefully that will be a thing of the past with these new spokes. Otherwise, I'll have to find a wheel build to put them into.

Thank you for your insights, Scott. I will definitely keep that in mind going forward.

speedevil 

I've not used the Revolution 2.0/1.5/2.0 spokes, I've chosen the Competition 2.0/1.8/2.0 spokes. I did read that the narrower gauge spokes will wind up more easily while tensioning, and releasing that windup could be the cause of the rim going out of true. I don't recall you mentioning anything about prepping the threads - I've always dipped the spoke threads in linseed oil before lacing them up.

Do you have a means to hold the spoke to prevent windup while tensioning? I don't have that type of tool, but while tensioning I go a little last the rotation that I think is correct and then back up a bit to try and prevent windup.

How are you determining the spoke tension?

Classtime 

It sounds like you will be unsatisfied with your new spokes no matter how they spin up or brake. You know they are too short. New TB14s, Dura-Ace, and a Paramount? Disassemble the wheels, save the spokes for a pair of A23s or some other high performace wheels with a smaller ERD, and measure again. Round up and don't subtract for spoke stretch. Btw, I have built up my TB14s 3 times since Santa brought them to me, and I now have them on 36 hole NOS 7400. I try to ignore the micro scratches in the high polish of the TB14s.

RiddleOfSteel

I have failed to mention that I do use spoke prep. Plus thick grease (lithium) at the contact point between the rim and spoke head. I've used Revolutions on two previous wheelset builds, with Competitions for the DS rear spokes. No wind-up issues or issues getting out of true quickly. They build up beautifully and without hassle. The old spokes are mysteries to me as far as make and model. Could be Wheelsmiths. They were fine on the old Mavics, and I took measures to prevent any wind-up or false tension numerous times with the TB14s, like going past and coming back.

Spoke tension is determined by both tone (via plucking) and a gauge.

RiddleOfSteel

As "correcting the spoke length" was the primary mission objective, and how that has not been achieved, yes, mission failure is not what I want to end up with. Especially if I'm building these for many years to come. My respectful deference to proven calculations (from given information) and friends with more experience than I didn't pan out. It's not the end of the world, and it's still frustrating, but it is correctable. I think the TB14 ERD is incorrect (hence Retrogression's number), thus dooming the calculations. I don't blame anyone. I just learn from this. More data points to keep in mind when building in the future.

I will measure again, more granularly, from the J-bend to the nipple, and see what I get. Then add 12mm. If I hadn't subtracted for supposed spoke stretch, I would have been on the money with 300mm.

I just re-measured. 288mm + 12mm for 300mm total on the spoke-showing side. I also spun in a spoke to the back side of the nipple and marked the exposed threads with a good marker. Unwound the spoke, and measured the unmarked threads (the ones that were buried) and came up with 2mm (2.14mm to be exact). This is confirmed across multiple spokes. It looks like I have my answer.

Micro scratches, I fully understand those. I do my best to avoid them, but they are a result of building a wheel--oh well! I've already started scheming to see how I can reuse these 298mm spokes, the inevitable result of cooling down and going, "Well I have them now. Best to not waste them." I'll be in Portland again soon, so I may "swing by" Covid-style (aka purchase them online first) and pick up some 300mm spokes. Or something similar. I'll get this straightened out.

Classtime 

Another thought:
Might have been mentioned earlier but how about a box of 14mm nipples?
[img]file:///page69image476[/img]


A picture from Roger Musson's book

RiddleOfSteel

Interesting idea, though I think I'd rather get the fundamentals (to me) correct than get longer (and possibly slightly odd looking) nipples. The price difference is of course appreciable!

noglider 

Longer nipples are NOT a solution to spokes that are too short! No, don't do it!

Classtime 

Why Not? If a 2mm longer nipple gives you 1mm of additional thread engagement. It is all good. If the longer nipple doesn't provide additional thread engagement, then it is a wasted effort.

RiddleOfSteel

Update for you all: The 300mm spokes threaded up to where they should and I've been able to get great even tension across many spokes. The wheel is strong and safe to ride.

However.....I must be the absolute stupidest amateur wheel builder or something must be up that I can't see, because the front wheel pulsing under braking still exists. In addition to multiple tension relievings during build up, and twice further re-truing of the built wheels, the problem still persists. Each successive truing has resulted in the wheel going out of true less. I'm doing the spoke wrench dance of going past and then back. I dial it in to within 0.5mm lateral run-out every time. The front wheel is, to the naked eye, when spinning it at a standstill and staring closely at it, true. Or plenty true enough.

Nothing like stupid stuff like this that makes you want to have never done the change in the first place. So let's see:

7400 Dura-Ace front hub: GOOD - No cracks, in perfect adjustment, spins smoothly
DT Swiss Revolution 300mm spokes: GOOD - Correctly laced (3-cross), some reluctant threading (too-thick Spoke Prep at times) but tension is very good across nearly all spokes
TB14 700C rim: NEW - Assumed to be good/round/etc, trues up without much trouble, both radially and laterally
Shimano R650 brake caliper: GOOD - brake arms adjusted to not be loose/floppy yet retaining free/smooth movement
Koolstop Brake Pads: GOOD - toe-in is shallow but within normal ranges, pads offer excellent grip, and communicate pulsing under any braking load
Soma Supple Vitesse EX tire: GOOD - tube mounted inside easily, and tire mounted without trouble, tire spins pretty darn true, with only a small "hot dog wobble" present (not uncommon for larger tires as we know)

Again, I've never come across this in all my riding and rim truing efforts. I am not being overly sensitive here, this is just crazy. If you can solve this riddle, because apparently I am completely unable to, I would GREATLY appreciate it. See any observation or assumption (like the rims being 100% ok) I'm missing or erring?

RiddleOfSteel

Further update today:

Swapped a different wheelset into the Paramount for testing--dark anodized TB14 laced to Superbe Pro hubs using the same DT Swiss spokes. Pulsing was calmer in some situations but sometimes there was rim-to-brake-pad chattering. So some slipping seemed to help, perhaps.

I looked at the toe-in of the brake pads and although they technically were, it was almost not there. I changed back to my troublesome polished TB14 wheel and then adjusted the pads for decent toe-in. Surprisingly, it greatly reduced it! That was a huge step forward. The soft pads and extremely shallow toe-in, in my mind, combined to exacerbate the problem through creating a sort of toe-out situation. At any rate, the feeling through the brake calipers is now back within what I would consider a normal range of feedback. The fact that this particular TB14 is not as cooperative (though improving) is another issue, but if it can be made good enough, then I think it should hold. @Dfrost and I talked at length about it today. I will need to run this wheel on other bikes to see if it is the Paramount's issue or a rim issue or a brake caliper issue or a me issue.

plonz 

This wheel building stuff is interesting and all... but 10%+ on a 39/24? I am not worthy.

repechage

I am pretty sure the new rims allowed for more spoke engagement. The original build is too short for me.
When I buy a bike, I Always take the tires off and check the wheels.
getting accurate measures of spoke seat dimensions is a task, I am about ready to make a tool, just need an accurate meter rule.

repechage

Due to the prior rim, take the brake pad holders off and look at the business side of the pads CAREFULLY- my reasoning is for a different problem, of embedded aluminum that will just eat up the new rims.
double check the tightness of the caliper mounting.
Double check the caliper assembly. I am not familiar with that caliper exactly, but what I would want to do is check for smooth movement AND no play in any pivot.

I just had a shudder on a front brake... double checked the caliper, tight but could have been tighter in the fork, double checked the caliper first off the bike, spring disengaged, removed the very minor play. reassembled, Vastly improved, not perfect, but better, Also installed Fresh pads, sanded the faces to remove the mold skin surface. (this is with an old wheel, that shows added wear at the spoke locations, Old wheel, like 45 years old. They will get replaced soon enough, Mavic Module E for reference)

An A/B swap of a different wheel, same bike, and that new wheel, different bike might be useful.

RiddleOfSteel

Hahaha, thanks. It isn't too long a grade, and I do run out of gas, but it's a good test of things. 39/28 or /24 or /21 all out of the saddle depending on how zippy I'm feeling. 42/24 on my Allez SE's low gear. That's less fun. Still, helps to have 175mm cranks and 200 lbs to press on the pedals. Like walking up stairs...in a fairly laborious way.

Classtime 

After you investigate the brakes (take the 4 pads and mix em up before you reinstall randomly&#128522, swap the rims -- front to back. Why not? Btw, I love my BR 650s. Just heard that they have been discontinued and I have 1 1/2 sets🤔