Sun Ringle Duroc rim failing

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Sun Ringle Duroc rim failing
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Posted: Nov 17, 2022 at 15:59 Quote
Hi there
I have repeated issues of cracks at spoke holes with Sun Ringle Duroc 45 rims.
First set of rims came with Salsa Timber Jack 2019 (Hardtail). Riders are fairly light (140 & 150lb)
After a very long bikepacking trip the rear rim showed longitudal cracks on ALL the spoke holes. (two idetical bikes and two cracked rear rims).
The cracks are about 2-3mm long at both sides of the spoke holes. ALL the spokes holes on rear wheels show this failure pattern. The front rims do not show any sign of cracking.
I got identical new replacement rims, and rebuilt the wheels (reusing spokes).

After another long bikepacking trip the two rear wheels (on two identical bikes) show the same damage again.
So now I have a sample of 4 rear rims with cracks on spoke holes

Could it be that the problem is the spokes rather than the rims? I.e the original spokes are straight gauge.
Would I be better off with double butted spokes?

Thank you for any suggestions/insight on this issue.

Posted: Nov 18, 2022 at 5:34 Quote
Chain reaction have a reveiw for a Duroc 50 where the reviewer claims theyve done 4000 miles hard XC riding. Not sure if the 45 is much different to the 50 but that sounds like a durable rim.

My thoughts are-
Are you massively overloading the back end of the bike?
Is the spoke tension to Sun Ringles spec? You'll need a decent spoke tension gauge to check
Are you using the correctly profiled nipples? I dont know if theres a variance in nipple profile but worth checking with Sun ringle that youre using the correct nipples

Posted: Nov 19, 2022 at 3:39 Quote
I built a 29er wheelset for my hardtail Fatbike with Duroc 40s, and I haven't had any isuues after about 3000km of hard trail summer riding, but no big jumps. I assume that the extreme spoke angle due to the wide Fatbike hubs would've exposed any weaknesses in the rims. For reference, I'm around 200lbs.

If I had to guess, I would say that it's a spoke tension issue.

Good luck!

Posted: Nov 23, 2022 at 11:10 Quote
(FYI I am the son of the author)

@zeeino What spokes did you use for your wheel build?

It is not a spoke tension issue. This is why I do not think it is. The first two sets of rims that cracked were the rims that came stock on the wheel purchased with the original bike, so they "should" be correctly tensioned.

Sunringle does not make this information easily available but from my research the suggested spoke tension is 100 - 110 kgf ref 1 , ref 2. The spokes used are 2mm round steel spokes. From the Park tool TM-1 spoke tool conversion chart this corresponds to ~23-25 using the TM-1 tool. I checked the tension on both the wheels that failed and they were below this tension

I then relaced the wheel to new Sunringle rims, tensioning to the recommended tension outlined previously. They are again beginning to crack after ~3000km of riding (hard trail riding with bikepacking gear)

1. This is why I am asking what spokes you are using. The spokes that came stock which my original wheels are single gauge spokes. Double butted spokes are more elastic so I am thinking they may apply a smaller peak load to a point on the rim? Butted Spokes Explanation

2. I am also curious about the use of nipple washers. DT swiss has their PHR technology which means that there is a washer with a curved profile to match the rim placed under the head of each nipple. This supposedly distributes the load and also makes it so the spokes can align in the direction of the load. I am curious if anyone else has used washers for non DT swiss rims? Sapim seems to make general purpose spoke washers.

Posted: Nov 24, 2022 at 18:25 Quote
The spokes I used are straight gauge with aluminum nipples. I bought whatever my lbs had in stock so not sure about washers.

I also have a Duroc 40s expert wheelset on a 2023 Trek roscoe that I built from a frameset this summer, but I only have around 500km on the bike, so can't really comment on durability. The expert wheels have 28 straight pull spokes, unlike the Fatbike wheelset which are 32 j bend spokes.

Posted: Nov 24, 2022 at 19:46 Quote
Have had warranty replacement with Hayes (Owner of sun ringle) for the same issue. They are cool people... I do enjoy the versatility of their hubs, but I did upgrade the hoop(s) to DT Swiss

Posted: Nov 25, 2022 at 23:02 Quote
@Dheieknens Thanks for the information. It is nice of you to say they are cool people, seeing the good in people even when there product seems faulty.

What hubs DT swiss hoops did you end up upgrading to? Did you use the original spokes or get different spokes.

Some new information to throw into this discussion"

The wheels are stock wheels which came a 2018 Salsa Timberjack (Build link). The in the build section its noted that the wheels are built with:

"SUNringlé Duroc 45mm 27.5", 148 x 12mm thru-axle, alloy straight gauge Wheelsmith spokes, brass nipples " (this was also the last year the timberjack was built with Duroc rims see 2019 timberjack)

This is interesting as if you go on the Hayes site they say that they use double butted Wheelsmith DB14 Spokes with alloy nipples to build their 40mm and 50mm rims (45mm rims are only available for OEM providers). I wonder if:
1. Hayes has changed the spokes they use to build there wheels from 2018 (i.e not they use double butted and they use to use straight gauge).
2. Since 45mm rims are OEM only Hayes laced them with straight gauge spokes to make them uber cheap and made the gamble that most people will not ride them long enough to see them crack.


Another thing I noticed is that the eyelets on the rims the Hayes website have reinforced eyelets whereas the eyelets on my rims do not (both the original rims 2018 and the "warrantied" 20% off discount rims I got last year). Again, I wonder if this is because the 45 rims are "cheap" OEM rims and the 40 and 50 mm are not?

Any thoughts/comments are much appreciated. Pictures below for what I mean about reinforced eyelets + a pic of my rim with cracked eyelets.

Sunringle Duroc 40 rim with reinforced eyelets
Sunringle Duroc 40 rim with reinforced eyelets

Sun Ringle 45 with cracked eyelet
Sun Ringle 45 with cracked eyelet

Sun Ringle 45 with cracked eyelet
Sun Ringle 45 with cracked eyelet

Posted: Nov 25, 2022 at 23:19 Quote
Eyelets definitely cost more to manufacture and strengthen a location that (I don't have to tell you) is a point of failure. N.B.: Your broken rims are "un-eyeleted". The metal insert is an eyelet.

Double-butted spokes are more elastic but the amount of elasticity would probably just have delayed the rim failure, not prevented it.

Note also that the spoke tension you measured on a wheel with all spoke holes broken is pretty much meaningless: the spoke tension dropped when the rim cracked.

Long story short, it sounds to me like you got a bad batch of rims.

Posted: Nov 26, 2022 at 11:17 Quote
Mmmhmmm, Ive seen that rim crack on a Duroc many times. I bought a DT Swiss EX 511, and new spokes were used as it was converted to a mullet wheel set.

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