Another Procore Failure - Discuss

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6/8/2015 9:02 AM
Edited Date/Time: 6/8/2015 9:04 AM

Yesterday we saw Harry Heaths Procore equipped wheel explode dramatically during his finals run at Fort Bill. After looking at the footage it's difficult to say exactly when the wheel folded. It was either when the pressure was released, or afterwards from the force of landing the drop without a tire. Personally I think the wheel is intact before he rides off the drop. Maybe someone else can take a look and see if you can see anything? It happens at around 1:09:07 into the Red Bull footage - you can actually navigate pretty easily to the incident on the Red Bull site.

At the first round Neko Mulally suffered a race ending puncture/wheel failure even with the Procore system. Somebody asked about this during the recent Schwalbe 'ask us anything' session on Pinkbike. Here is Schwalbe's response;

"Neko actually suffered a destroyed rear-wheel rather than a tire fault. This section was a very tough rock-section with a big compression and a massive rock that not only Neko hit with his rear wheel but also Andrew Neethling, picking the wrong line and hitting the same rock. The impact on Neko’s wheel was so hard that the rim collapsed. Procore might have the ability to absorb impacts which are way higher than what just a DH tire can handle, but Procore is still not completely flat-proof."

It could be easy to explain Heath's incident as a destroyed rear wheel rather than a tire fault, but I'm really not sure that is the full reason. I have a bunch of points/questions that I have listed below. Maybe someone with more knowledge or someone from Schwalbe can provide some answers?

- One of the claimed advantages is that riders can run lower pressures in the outer tire. If riders are running lower pressures and the Pro Core is soaking up a lot of the big impacts, are those impacts being transferred more directly to the rim, because the pro core is at a much higher pressure (ie harder)? Is this causing rim failures?

- Does the rim/Pro Core experience more impacts because of the reduced volume of the outer tire, even at a fixed pressure?

- Previously on rocky tracks, riders would likely up the pressure by a couple of psi to prevent pinch flats. Are your riders still doing this or are they relying on the system to completely prevent punctures?

- We have seen riders complete entire race runs on a rim alone (Gwin@Leogang is one example) so it seems that wheels are strong enough, yet we have seen examples of Pro Core equipped wheels undergoing catastrophic failure in that last 2 world cups. Is the Pro Core system protecting the rim too much and so when a failure does occur, it is sudden? Previously you would pinch flat as a warning to slow down before destroying the wheel. Any concerns about rider safety due to sudden failures?

- If Pro Core isn't eliminating punctures/failures, what's the point? Should we just take our chances with a dh tube/tubeless/ghetto etc?

That's about it really. If I think of anything else I'll add it or maybe somebody else has questions of their own.


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6/8/2015 10:42 AM

You pose some great questions here, Oz. I'll notify the guys at Schwalbe and get them to hopefully hop on here for a response.

To me, it looked like Harry's tire went just before the drop, and the landing of the drop did his wheel in.

The Pro riders I've spoken with have all indicated that they still run normal pressures in the tire chamber to prevent it from squirming in turns and on jump faces. They may forego the extra few psi on rocky tracks and instead rely on the inner chamber to help prevent flats, however.

I think one of the biggest issues with tire failures has to do with some riders running lighter casing tires to compensate for the system's added weight. It's just easier to puncture/slice a sidewall.

Vital will be testing the system soon, and I plan to do quite a bit of experimenting with pressures and various tires/rim combinations to get a good feel as to who it's best for and on what type of terrain. Lots of stupid hucks into rocks planned too, in the name of science.

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6/8/2015 11:29 AM

Lots of stupid hucks into rocks planned too, in the name of science.

Approved.
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6/8/2015 11:32 AM
Edited Date/Time: 6/8/2015 11:36 AM

bturman wrote:

You pose some great questions here, Oz. I'll notify the guys at Schwalbe and get them to hopefully hop on here for a response.

To me, it looked like Harry's tire went just before the drop, and the landing of the drop did his wheel in.

The Pro riders I've spoken with have all indicated that they still run normal pressures in the tire chamber to prevent it from squirming in turns and on jump faces. They may forego the extra few psi on rocky tracks and instead rely on the inner chamber to help prevent flats, however.

I think one of the biggest issues with tire failures has to do with some riders running lighter casing tires to compensate for the system's added weight. It's just easier to puncture/slice a sidewall.

Vital will be testing the system soon, and I plan to do quite a bit of experimenting with pressures and various tires/rim combinations to get a good feel as to who it's best for and on what type of terrain. Lots of stupid hucks into rocks planned too, in the name of science.

Make sure you throw it on a rim that is north of 30mm too. This could mitigate much of the squirming... I think the ticket for the system will be a 35-40mm internal width. Just my guess.


EDIT: Just going back to a 25mm rim - which is quiet common on the WC circuit I'm noticing squirming that was completely absent on the 35mm rims I came from. Even at significantly higher pressures (on the narrower rims). Point is I couldn't go lower on the 25mm rims even if I wanted to.

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6/8/2015 11:39 AM

Am I correct in understanding that the inner tube has a really high pressure that's supposed to protect from rim strikes and whatnot(at least that's the reasoning)? My guess is that when the sidewall slices(because they're thin) and then blows the inner tube from something like a rock strike that the pressure and load is dispersed towards the rim. This kind of pressure can't be good especially when hitting rocks or a drop.

To me, it looked like his tire blew first and then the drop destroyed the rim. The tire clearly blew before the drop and his wheel seemed to be rolling after that point. But after the drop everything was wasted.

Part of the double edged sword of being a sponsored rider is you have to test things before they're proven. That has to be tough then to achieve results if the products aren't working perfectly.

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6/8/2015 1:52 PM

Thanks for the replies. I use Schwalbe tires on all my bikes so I hope my original post didn't sound like I am bashing Schwalbe in any way. It's a natural progression for me to 'upgrade' to the Procore system but after seeing two high profile failures I'm starting to have doubts.

I'll look forward to reading the Vital review amongst others before making any decisions.

@xyian - I did some more research and the inner core is inflated between 4 and 6 bar (68 and 87psi). The only experience I have of those pressures is on my road bike. At 90psi I can imagine that inner core is pretty solid.

I also looked at the footage again and his tire is definitely off the rim before he goes off the drop. Could the Procore rapidly deflating be the cause of the tire coming off the rim? A snakebite is a rapid deflation but more often than not the tire stays seated and will only come off if you continue to ride with zero pressure in it.

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6/8/2015 2:50 PM

Here's a response from Schwalbe North America:

"We’re obviously always testing to product with our teams, and they have a slightly different tire than what is currently available on the market. Needless to say, the damage to both Nico and Harry’s wheels was from poor line choice. Failures are not impossible to prevent, but in both WC races this year we had significantly fewer mechanicals than in previous years. It's just really easy for people to see Procore if something happens."

It's good to hear about progress from year to year.

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6/8/2015 2:53 PM

I guess they should have made it black.

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6/8/2015 4:55 PM
Edited Date/Time: 6/8/2015 4:56 PM

Oz_Taylor wrote:

I guess they should have made it black.

I can't "like" your comment here, so I'll just quote you to the world... Given that road bikes run such high pressures on such tiny rims and rim makers surely use similar technology on our heavier DH rims, I don't think that the inner chamber pressure is the issue. Schwable IS it sounds like experimenting with thinner tires, perhaps also the rim manufacturers are experimenting with lighter rims for Pro Core riders? And finding a base level it seems.

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6/9/2015 2:02 AM

Oz_Taylor wrote:

I guess they should have made it black.

Big Bird wrote:

I can't "like" your comment here, so I'll just quote you to the world... Given that road bikes run such high pressures on such tiny rims and rim makers surely use similar technology on our heavier DH rims, I don't think that the inner chamber pressure is the issue. Schwable IS it sounds like experimenting with thinner tires, perhaps also the rim manufacturers are experimenting with lighter rims for Pro Core riders? And finding a base level it seems.

I guess my last comment was a little flippant, but I wasn't blown away by Schwalbe's response to be honest. What they are saying is; I'll be the guy on the trail who still gets punctures, but now everyone can clearly see I've spent $$$ on this latest technology only to end up in the same situation.

I think a simple 'we are looking into it' would have been more constructive.

I think it's awesome that Schwalbe are investing in R&D to develop technology like this. Like I said, I run Schwalbe and I think they make the best products (and the price is great, at least here in Europe). Somebody has to be the first to develop products and I suppose by using racers to test the products they are going to be under public scrutiny, but this product is ready for sale so I think the questions need to be asked.

I think you are right though - racers are pushing things to the limit, whether it be thinner tires, lighter rims etc. Most of the customers who buy Procore probably won't push it to the same level and it might completely solve the puncture issue for them. Let's hope it does because punctures are a PITA for everyone.

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6/9/2015 8:54 AM

Oz_Taylor wrote:

I guess my last comment was a little flippant, but I wasn't blown away by Schwalbe's response to be honest. What they are saying is; I'll be the guy on the trail who still gets punctures, but now everyone can clearly see I've spent $$$ on this latest technology only to end up in the same situation.

I think a simple 'we are looking into it' would have been more constructive.

I think it's awesome that Schwalbe are investing in R&D to develop technology like this. Like I said, I run Schwalbe and I think they make the best products (and the price is great, at least here in Europe). Somebody has to be the first to develop products and I suppose by using racers to test the products they are going to be under public scrutiny, but this product is ready for sale so I think the questions need to be asked.

I think you are right though - racers are pushing things to the limit, whether it be thinner tires, lighter rims etc. Most of the customers who buy Procore probably won't push it to the same level and it might completely solve the puncture issue for them. Let's hope it does because punctures are a PITA for everyone.

I think they just said the honest truth. They're under a bit of fire because people expect it to perform incredibly well, and it's easy to see when things don't go as planned due to less than perfect line choice or otherwise.

This is the important part: "...in both WC races this year we had significantly fewer mechanicals than in previous years."

Care to count up the flat Schwalbe tires from previous Fort Bill races compared to this one?

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6/9/2015 11:35 AM

Poor line choice? Isn't that what causes 99% of flats on a normal set up?

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6/9/2015 12:12 PM


I get that the expectations on Procore were pretty high; also due to Schwalbes own claims about how it would eliminate pinch flats. But I also buy Schwalbe's comment that they had much less mechanicals this year (I counted two flats in Fort Bill's top 20 qualifiers). Remember how many of the top female riders had flats last year. While different track conditions might have something to do with that, I still think that Procore contributed to that. It would also be interesting to hear from an WC Insider how many of the non-Schwalbe riders use Procore (in case they already can get it). As Schwalbe, I also think that Harry's as well as Neko's flats were both just very bad moves. If you look at how hard Harry has his rear wheel drop into that hole, where the tire blew off, I wonder, whether Procore-riders think much less about such decisions because they think they can ride as if their rear tire was "made of steel". Although it might avoid a lot of flats, which might occure otherwise with such a style of riding, it doesn't make your rear wheel invulnerable.

However, as far as I know, one of the major benefits of Procore is how the tire-suspension system is much better able to react to fast hits as the tire transforms slightly easy until it reaches the core, but leads all the remaining force into the (damped) suspension instead of the (undamped) tire. That's also what it received most praise for in an early review on the German mtb-news.de.

I also think that for most non-WC riders, it might just save us from a lot of flats and give us the opportunity to get a bit more grip, if needed. Still I'm not sure, if that's worth the price; my current (old school) rims don't allow me to use it anyway.
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6/9/2015 1:20 PM

the idea of procore is great, I also would like to have no more flats and an improved grip!!! ... but there are also drawbacks (like with everthing) which have to be considered.

From my point of view (as an engineer who have to build light durable rims), something have to be mentioned. The inner camber have to be filled with 4-6bar (58-87psi). That is a huge preload for the rim.
The force on the rim flanges is not the major issue, because this force is caused by pressure * projected area of tire height => procore inner camber is only est. 1/3-1/2 heigh of normal tire, due to that sideway force to rim is not that much increased. But there is also pressure against rim bed which compress the rim. Here we have 4-6 times more pressure/force than with e nomal set up (4-6bar instead of 1.5-2bar)! Area stays the same (nowadys rims become wider and wider, this makes it even worse).
Everyone who thinks this is not worth to consider, you can check this quite easy with spoke tension (Tensiometer):
- check tension without tire
- check tension with normal set up (you will see allready a noticeable decrease)
- then do the same with procore with 6bar in inner camber, this will be stunning....

For a stable wheel a high enough and even spoke tension is THE key. Now you can say: No problem, I will re-tension up after inflating Procore... but like that the preload/compression force on rim is getting only bigger => less buffer for big impacts, rim tends earlier to collapse.

I can not judge if Neko's (who rids the exact same EX 471 rim than Gwin tireless Leogang) and Harry's impact were that bad that every wheel would have colapsed, but when I remeber Gwin's run (full rock gardens witout tire) and the facts mentioned above then....

Please don't get me wrong, I don't want to bash Procore! I will try Procore by myself. But it doesn't help for wheel stability!!! Consider this....

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6/9/2015 6:49 PM

as for procore i don't know, but have been riding a set of wheels with the dean easy product, similar to schwalbe, but instead of a tube and tire is a special made tubular making it lighter than schwalbe. and riding month's on the set up i can say that you improve indeed the suspension of the tire because the chamber of air inside the tire is smaler, making it more progressive, you don't make the tire burp air, you still can fell the tire bending but to the point it it's the tubular it stops.

did 2 km on the flat tire(cuted sidewall) and i have much more controll than if i was only on the normal set up.

for me the only downside of this sistems is cost and a bit off rotational weight

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6/9/2015 9:32 PM

I had a feeling that might be the issue @andu81. I was figuring the inner tube was creating undue pressure on the tension of the wheel. Therefore, if that blows then the wheel is going to let loose.
Schwalbe's response seemed VERY defensive and not very proactive. If I'm spending that kind of loot on a tire I expect a lot. Granted, I don't run DH but I also won't spend $90 on one of their tubeless tires when I can get a top of the line Maxxis for $60.

Also, in regards to the people in the top 20 not flatting...how many of them actually ran Schwalbe vs another brand?

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6/10/2015 5:33 AM

xyian wrote:

I had a feeling that might be the issue @andu81. I was figuring the inner tube was creating undue pressure on the tension of the wheel. Therefore, if that blows then the wheel is going to let loose.
Schwalbe's response seemed VERY defensive and not very proactive. If I'm spending that kind of loot on a tire I expect a lot. Granted, I don't run DH but I also won't spend $90 on one of their tubeless tires when I can get a top of the line Maxxis for $60.

Also, in regards to the people in the top 20 not flatting...how many of them actually ran Schwalbe vs another brand?

schwalbe tires are expensive in the us?
if i buy them in portugal probably 50 to 60 €, but from onlyne retailer's more like 30 to 35, if it was maxxis (exept the 60a) would be at least 10€ more per tire


answering to your question about the top ten, wen't to see the result's and buy looking at the top 20 i tink like 8 or 9 are on schwalbe

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6/10/2015 7:53 AM

Long time listener, first time contributor. Something to think about is that most all MTB rims have a max psi limit that the rims are designed around, generally in the ballpark of 60psi. Anything above that may cause the rim to split, either at the bead seat or the tire well. It'd be interesting to look into what rims these guys are using and then look into what the manufacturer recommends for a max psi rating, then find out what they were running in their ProCore set up. A combination of exceeding recommended pressure and impacts may very well contribute to the failures they experienced. As with all things, it's usually a combination of factors that lead to catastrophic failure.

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6/10/2015 8:27 AM

And a little web search shows they're both on DTSwiss, which has this chart on their website:

http://www.dtswiss.com/Resources/Tech-PDF/Tire_Pressure_Dimension

It shows that if they were running their ProCore set ups over roughly 50psi (roughly, due to possible differences in tire and rim dimensions), they've exceeded the recommended pressure of the rims.

So now questions need to be asked to the rim manufacturers and their stance on ProCore setups on their rims.

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6/10/2015 8:34 AM

Just fwiw I am guessing those tire pressure ratings have more to do with "safe pressure to ride the tire" than anything. EG - tire is less likely to hold onto the rim, not that the rim will catastrphically fail. I'll bring a real engineer type in here but as others noted, road rims commonly handle 120+ psi.

The difference is carbon stuff but still - I'd bet dollars to donuts that is not what is creating the issue.

J

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6/10/2015 9:23 AM

I've seen two rim wells split on MTB rims when used for the wrong purposes (29er rims with road tires, different rim manufacturers) and both set a maximum psi for the MTB rims that is considerably lower than their road rims. That's how I found out about these pressure ratings, trying to warranty em for the customer. That didn't work out too well. Not saying it's the end all be all with the ProCore set ups, but it may be a contributor. That's why I feel it important to see what the rim manufacturers have to say about it, see if they plan on testing them and which method of testing they'll use, Cannondale or CEN test standards, with the C'dale test being far more destructive than any wheel test required by any government body. On the surface ProCore does seem like a killer idea, but it does require the other bits to be in compliance with its design needs.

(BTW, 22 years working as a mech in shops, 10 years in the manufacturing side of the bike industry, and am a mechanical designer by education and trade. Not trying to sound like an arrogant a**hat and say I know my stuff, because if there's one thing I know it's I don't know enough. There is still much to grok.)

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6/11/2015 7:50 AM

I'm more inclined to say this system works. Simply because we've see two failures out of how many successful practice/testing/race runs.

I think people assumed (and Schwalbe supported) that you can run pressures far lower than with normal tubeless. This doesn't make sense to me. The system is meant to protect your rim not keep your tire on. I always thought that if I had Procore i'd run the same pressure as normal but now have added rim protection.

I've seem people online state that they were excited to start running sub 20psi... This is confusing. Do they actually ride? The tire would be so pliable (especially around any kind of corner) that could easily blow off the rim. When it does the procore will soon follow. Are people not realizing that procore doen't have a bead that secures it into the tire?

My gut is telling me that procore with an appropriate tire and psi the will yield less failures than a tubeless or tube system alone with the same tire and psi. At least it'll reduce the number of dings and dents in my rims.

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I'm Slow

6/11/2015 8:05 AM

Couple of thoughts...

1) Wouldn't a rim take more PSI (pounds per square inch) in normal riding situations than a static 80psi would place on it? Smashing wheels through burly terrain has to load the wheel more than any tire no? Just guessing...

2) Ryan the system *is* supposed to keep your tire on better and allow lower pressure. You are basically able to tune your "tire suspension curve".

The future would be something where there are mutliple chambers and you can tune both the pressure *and* size of each chamber. This would allow the ultimate grip while still resist rolling.

Finally, these low pressures will really only work with wider rims. If you notice, the company worked in tandem with Syntace who is developing wide rims. Having run a 35mm (internal) width rim, I can say it allows a totally different set of tire pressures without worrying about burping/rolling....but at the expense of an overly squared off tire shape.

To sum it up I think this idea has legs but will take a few years to dial in. I also think wide rims and tires to suit said rims need to come into fruition for the system to realize its potential.

Just my $0.02.

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6/11/2015 8:35 AM

I don't buy the 'poor line choice' story - and even if it is, that's a weird excuse to use when trying to sell a system to average riders who are even more likely to make bad line choices.

It looked like the place where Baz flatted is where you drop down onto a wooden bridge - it's completely flat and it seemed it was just the compression that blew the system.

Obviously no system is completely flat proof - and fair play to them for thinking outside the box with it - that's more than any other tyre manufacturer has done.

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