Rim cracks at spokes

Jim Junkie

Used to sell drugs, now he just takes them
Went to ride home from work yesterday and came down to a bike with a flat tire. Not unheard of as I quite often collect a thorn / thumb tack / other sharp object in the tire on the commute and get a slow leak. However, upon pulling the tire off, I noticed this:

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:oops:. For context, the wheels are on my gravel bike commuter and are Spank Flare 24 OC rims with DT Swiss Comp spokes into Hope Pro 4 hubs. Mileage is about 6000km at this point.

Now, I had noticed a hairline crack at one nipple a few weeks back (and neglected to do anything about it), however this was obviously far progressed from that. Closer inspection also revealed it was happening to varying degrees at 4 other spokes as well, all drive side rear. The worse cases have resulted in some minor buckling of the rim as well it would seem.

Now, my first inclination at this point was over-tensioned spokes and a obligatory visit for me to the confessions thread (this may still happen). I built these wheels (with only sparing use of a tension meter :rolleyes:), I alone ride of them (roughly, with a heavy me and a heavy load), so any fuck-up responsibilty lies squarely with me. So the first stop was to get the tension meter out and see just how badly I got the tension wrong.

Turns out, it's all bang on or just under Spank's recommended 110-120 kg.f with vary little variance, although the damaged ones are reading a little lower (I assume because of some tension released with the deformation). I also don't exceed maximum tyre pressures either (although do tend to operate at or near the 70psi limit).

So what have I done wrong here? Am I too heavy? Total ride weight can get up there, with me at 90+ kg and cargo can get up around 20kg (although mostly around 5). I do occassionally due abusive things to it, like riding stairs & stuff, but not what I would consider beyond normal shenanigans. I'm still leaning towards it being an error in the build, but I'm just not sure what at this point. I'm going to build a fresh one with the same rim, so it would be good to know what the hell I've screwed up to avoid the same mistake again.
 

dirtdad

Wants to be special but is too shy
I'm a garage hack who's only ever trued wheels and replaced spokes. Never built anything proper. So grain of salt.. etc.

Do you have nipple washers in there? The rims aren't eyeletted, and so I'd expect you might get better load distribution with some washers.
 

rangersac

Medically diagnosed OMS
I have busted far more stuff commuting than on the MTB, and like you are on the wrong side of 90kg with a minimum of 6-7kg of cargo for the run. As the previous poster has suggested eyeletted rims, and a minimum of 32 spoke holes, and preferably 36 if on the rear would be the go. Also definitely run lower pressures than close to the maximum, my commuter has 45c tyres and I run those down around the 60 mark, with the added bonus being a much nicer ride.
 

Flow-Rider

Burner
Possible error, how did you work out the spoke tension from the spoke gauge? I never build wheels that don't have eyelets without nipple washers either.
 

Jim Junkie

Used to sell drugs, now he just takes them
I'm a garage hack who's only ever trued wheels and replaced spokes. Never built anything proper. So grain of salt.. etc.

Do you have nipple washers in there? The rims aren't eyeletted, and so I'd expect you might get better load distribution with some washers.
I had considered that, but according to Spank, any May 2019 or later had washers built in (These were October 2019). The FAQ only addresses Spank 350/359 rims, and there appears to be very little information on the Flare's, but I'll definitely be checking on the fresh rim before lacing.


I have busted far more stuff commuting than on the MTB, and like you are on the wrong side of 90kg with a minimum of 6-7kg of cargo for the run. As the previous poster has suggested eyeletted rims, and a minimum of 32 spoke holes, and preferably 36 if on the rear would be the go. Also definitely run lower pressures than close to the maximum, my commuter has 45c tyres and I run those down around the 60 mark, with the added bonus being a much nicer ride.
Yeah, I figure I'd do the same. I run 40c and generally they're about 60psi, but they do occassionally get put up at 70. The rims were 32H too. Given i'll be salvaging the hub, i'd prefer to keep it there unless there was a smoking gun telling me I need 36.
 

rowdyflat

chez le médecin
I have commuted all my life on 28 -35 mm tyres and have never done that to a wheel.
I would not ride down stairs on a commuter just occasionally hop a gutter.
would go more spokes 32 or 36 plus eyelets so the tension per spoke should be less .and not use those rims again as I think they are faulty .
 

Jim Junkie

Used to sell drugs, now he just takes them
Possible error, how did you work out the spoke tension from the spoke gauge? I never build wheels that don't have eyelets without nipple washers either.
Through the TM-1 conversion guide: https://www.parktool.com/product/spoke-tension-meter-tm-1

My notes since going back to check are below. Spokes installed are DT Swiss Competition, double butted. I took the measurement around midline of spoke between the last cross and the nipple, being sure to avoid the thicker spoke section. Readings were coming back right around 21 consistently, but down around 17 on the cracked ones.

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Jim Junkie

Used to sell drugs, now he just takes them
Possible error, how did you work out the spoke tension from the spoke gauge? I never build wheels that don't have eyelets without nipple washers either.
Looking further into this, it seems to be just the 350/359 radially complaint wheels with the built in washers, so I will be adding those to the build next time around
 

Flow-Rider

Burner
Through the TM-1 conversion guide: https://www.parktool.com/product/spoke-tension-meter-tm-1

My notes since going back to check are below. Spokes installed are DT Swiss Competition, double butted. I took the measurement around midline of spoke between the last cross and the nipple, being sure to avoid the thicker spoke section. Readings were coming back right around 21 consistently, but down around 17 on the cracked ones.

View attachment 373523

View attachment 373525
Those multi use charts can be out between spoke brands, that looks like it's for straight gauge spokes. Check your spoke gauge against another spoke gauge that's been proven or build a jig and tension the exact spokes you are using to what you need for the wheel and get a reference reading from your spoke gauge.



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Lucaw

Next in line
I had this happen to my mtb when I slammed into a rock. (They were dt Swiss 420 rims on specialized hubs) Could be that you hit a curb or a stair on a square edge and cracked it.
 

Jim Junkie

Used to sell drugs, now he just takes them
Those multi use charts can be out between spoke brands, that looks like it's for straight gauge spokes. Check your spoke gauge against another spoke gauge that's been proven or build a jig and tension the exact spokes you are using to what you need for the wheel and get a reference reading from your spoke gauge.
I wouldn't have expected much of a difference between straight gauge and double / triple butted with that measurement style, provided it's measuring on a uniform section?
Admittedly though, I'm usually primarily concerned with uniformity of tension, rather than magnitude, so haven't been to worried about any variance which might crop up due to brand or gauge calibration. What sort of error would be anticipated though, are we talking about 5% or is 20% feasible?
 

Oddjob

Merry fucking Xmas to you assholes
I would put that down to a combination of lack of eyelets or washers and low spoke count.

When you rebuild make sure to use something like linseed oil or lanotec to lube the nipples and washers. This will help to prevent spoke wind up and ensure consistent tension readings.

Sent from my SM-G970F using Tapatalk
 

SummitFever

Eats Squid
Aluminium rims are a consumable item. Over time, they will all crack at the spoke nipples (non-eyeletted, eyeletted, with and without washers). How soon they will crack is largely due to how much you ride, how much you weigh and how many spokes the wheel has. The shortest lived combo will be low spoke count and thick spokes (eg. straight gauge).
 

ozzybmx

taking a shit with my boobs out
Spank's recommended 110-120 kg.f
That's pretty high :oops:

I have detensioned a few of my sets of wheels that I needed to be reliable, highest tension in the 90's going on that very Park Tool graph and using the same tension meter.

Dropped my old enve wheels down from ~120kgf into the mid 90's and my bike packing wheels, also 90's now. Pop a spoke at 120kgf and low spoke count, the wheel deflects 2-3cm and hits the chainstay, game over and carry bike home.

New sets of wheels I build these days are at absolute max touching 100kgf, aim for mid 90's.

Also as said, linseed oil as a lube and locker.
 

The Duckmeister

Has a juicy midrange
Maybe cutting it a bit fine with regards to bouncing off the tension limit; if they're highly strung and used hard there's little room for forgiveness. You don't want to go too soft, otherwise you'll chow through spokes instead, but maybe with the rebuild cut it back to 100-105kgf. Butted spokes such as the Comps do disippate some of the stress, but there's only so much they can do.
 

PJO

in me vL comy
Is it just the picture or is there a slight ding in the rim right at that nipple?
Edit: in the bead I mean
 

Flow-Rider

Burner
I wouldn't have expected much of a difference between straight gauge and double / triple butted with that measurement style, provided it's measuring on a uniform section?
Admittedly though, I'm usually primarily concerned with uniformity of tension, rather than magnitude, so haven't been to worried about any variance which might crop up due to brand or gauge calibration. What sort of error would be anticipated though, are we talking about 5% or is 20% feasible?
That exact gauge you have, I've seen someone post up on a wheel building page that it was out 20KGF at 110KGF, the dial gauge type are a bit more accurate but even they need to be checked. It's worth checking to be sure, you could have a warranty claim on the rims.
 

ozzybmx

taking a shit with my boobs out
I've seen someone post up on a wheel building page that it was out 20KGF at 110KGF
That's massive :oops:

Suppose its like your shock pump, there is a massive difference between pumps, you learn what works for your pump/tension meter. I have pulled a spoke through a carbon rim before on one occasion, it was replaced free of charge but your discrepancy comment is good food for thought.

BTW I use that exact TM-1 Park Tool tension meter and have done since I started building wheels with a bit of thought of what was going on.

An easy Gmail search says I bought my TM-1 in 16/7/2010 from Jenson.
 

Oddjob

Merry fucking Xmas to you assholes
Keep in mind that 120kgf, when you build will be less once you have mounted and inflated a tyre.

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