Pacenti SL23 cracking issue

[seayel]

My Pacenti's (1st generation) had a catastrophic failure on the last turn of a descent. About 5 seconds from starting my turn I hear a sound similar to a pebble being shot out from under my tire, and didn't think anything of it until I tried to lean into the corner and realized I had no control of my rear wheel. I high-sided straight through the turn and slid under a parked car.

A spoke had completely ripped a 3-cm long chunk out of aluminum out of my rim, so the tube had probably flatted immediately.

I want to state that this happened a week after having them trued and tensioned by my LBS, who generally do excellent work, but acknowledged that they could have created an issue or worsened an existing flaw in the rim. They are taking care of the warranty on the rim, but regardless, it doesn't seem like a problem that should have ever occurred in the first place.

[velomane]

Wow, quite the story seayel. I gather you're okay, health-wise.

[Ginsterdrz]

Yep-hope you're okay buddy-sounds like a nasty experience.

Few questions:
How old were the V1 rims? Mileage?
How many times had they been trued?
What spokes were the wheels built with?
Would you ride SL23's again?

I'm just about to order some V2 23's but I'm now starting to have reservations.....

[WMW]

A spoke had completely ripped a 3-cm long chunk out of aluminum out of my rim, so the tube had probably flatted immediately.

Wow! That is a big hole. Never seen that before. Typically cracks will spread from the spoke hole and eventually a small spot will give enough to let the nipple pull through.

The weird thing is you should have had plenty of warning before that happened. Like weeks before. Or more.

BTW, that isn't where the tube is located. There is an inner wall near the tire that contains the tube.

[seayel]

Yep-hope you're okay buddy-sounds like a nasty experience.

Few questions:
How old were the V1 rims? Mileage?
How many times had they been trued?
What spokes were the wheels built with?
Would you ride SL23's again?

I'm just about to order some V2 23's but I'm now starting to have reservations.....

The wheels were about a year old (just outside of the technical warranty period, so credit to Pacenti for honoring it regardless), and had at most 4500 miles. They were serviced twice, and built with DT Swiss 2.0 spokes. Beyond the issues with tire mounting (truly a PITA experience), they were terrific wheels, until their sudden demise. I live at the foot of Mt. Baldy, so they saw a good variety of terrain.

Riding again? Probably. My front wheel is completely fine, and the fact that my LBS is taking care of the warranty issue for me indicates that they may feel some responsibility for what happened. I'm not a wheelbuilder and can't speak to tension requirements though.

BTW, that isn't where the tube is located. There is an inner wall near the tire that contains the tube.

Yep, but the decompression (probably not the right word) at the point of the rim failure also buckled the braking surface and collapsed the rim tape. I can't state with any certainty that it all happened simultaneously of course.

For kicks, here's the real casualty of the crash: my chainring. It struck the rim of the parked car, and evidently that rim was actual chrome steel.

[KWalker]

When my rims cracked they were built up under tension. The cracks formed at the spoke hole, but it wasn't just a single crack, but rather multiple cracks as the nipple pulled through. Mounting the tires on both gens is a PITA, but I found that you just have to be a bit more thoughtful of seating the tire completely on one side, pulling the other off and putting the tube in.

[bm0p700f]

Kwalker thats how the rims fail. When i see a wheel out of true i always suspect rim cracking. I see it alot on a varoety of wheels. Generally when i add tension but the rim does not respond the way i expect, i worry and really stress the spoke to see what happens. If i see a crack appear i know the problem. Better it happens in the stand than on the road. Rims crack. The v1 sl23 is prone to it than others but few rims are immune. They have to be be pretty stout not to crack ever.

[WMW]

About 5 seconds from starting my turn I hear a sound similar to a pebble being shot out from under my tire, and didn't think anything of it until I tried to lean into the corner and realized I had no control of my rear wheel. I high-sided straight through the turn and slid under a parked car.
A spoke had completely ripped a 3-cm long chunk out of aluminum out of my rim, so the tube had probably flatted immediately.

Regarding this incident, I doubt the rim was the cause. It would not have flatted your rear tire or caused you to lose control of the rear wheel, but a flat rear tire would have done that. A pinched tube tire failure will make a loud pop.

[KWalker]

I can say I've yet to crack any other rim aside from a Zipp 808. I used Kirk's recommendation of tension and nipple washers, so if manufacturer's specs don't prevent it I'd say its not normal.

[Mr.Gib]

Seayel, that is a crazy failure. Very disturbing. Sure rims can crack but I can't recall a failure like that. Has me seriously wondering about what wheels to take to Europe - the thought of that failure on some of the descents I have version 1 on the travel bike. Might have to juggle some cassettes around and steal my version 2 set off my summer bike.

As a side note the version 2 rims with the smaller bead hook result in massive tire volume. On one of my bikes I had to downsize to from 28mm to 25 mm when I switched to version 2.

[fignonsbarber]

I was 1 for 1 with the version 1 of the sl23. I had 4 spokes pulling threw cracks after less than 400 miles.

[Miller]

This must be the dreaded SL23 spoke hole cracking? This a driveside 24h rear. I was wondering why it had gone out of true after being stable for two years.

Any recommendations for a similar rim to rebuild with?

[KWalker]

The new Forza is actually supposed to be good. They switched rim suppliers for this and a few other models. In my research I couldn't find a single issue with the SL25 disc, so hopefully these times are behind them.

A nice alternative are the Kinlin XR22T and the new HPlusSon

[Miller]

Thanks for those recommendations.

[hmai18]

Also consider the Easton EA90SL rim.