Schwalbe Procore – Update: Pressures and Running Flat
When it comes to maximizing the traction and the breakdown protection, SCHWALBE’s Procore is a real milestone.
When we introduced this system in the OOB article, that being SCHWALBE’s dual-chamber tire system, Procore , it promised to be a real revolution for those looking for more and more traction and comfort: Combining the grip and the rollover behavior of a low pressure plus tire, plus the puncture protection exceeding anything else, and to top it all off, the fact that the Procore tubeless system results in a main tire that is almost sealed even without air. And all this is almost invisible from the outside.
Granted,you must first swallow the additional weight of up to 250g with respect to a previous tubeless setup, but to be honest, I do not, given the above-mentioned advantages think that is a huge drawback. The price though, at 195.- Euro, is certainly not easy to ignore.
In recent weeks, I had the opportunity to play around a lot with the air pressures in practice. Reminder: Schwalbe itself suggests pressures from 0.8 to 1.5 bar/16-22PSI for the main chamber and 4 to 6 bar/58-87 PSI for the inner chamber.
Traction and comfort aplenty – but whoever travels with too low a pressures must reckon with the screeching noise.
The first attempts were done with 1.25 bar/18PSI front and rear … and I was thrilled. But who has ever stopped looking for more traction and comfort via tire pressure? The lower the air pressure, the higher the traction and comfort. I was not cincerned about flatting with those low pressures with the Procore system, but how about the steering stability and the riding experience?
So I have gradually lowered the pressures. And I was surprised how I was able to go down to below 1.0 bar/14.5PSI on moderate trails. Here you can certainly feel that the tire in some situations loses steering precision, but under normal circumstances it is also still very mobile … with excellent comfort and grip. Only in aggressive cornering on hard ground and landing from jumps did I feel the tire deflecting away violently. The terrain and riding style determine at what point one no longer feels the increasing instability acceptable. For me personally (90 kg/200lbs incl. luggage) and my rooty trails, I found the 1.1 bar/16PSI front and rear the best and I have increased that to 1.25 bar/18PSI only for trails with many jumps. Increasing pressures to over 1.25 bar/18PSI is pointless because the tire simply only goes more and more like a normal tire and would thus only reduce Procore to a run flat protection for extreme cases.
On the way toward the optimal air pressure, however, when I was running it lower, I had to get over an interesting hurdle: When riding over obstacles with Procore at lower PSI settings I have noticed a strange creaky noise. What’s happening here? Very simple. Once the main chamber is highly compressed, the outer tire touches the Procore inner tire and then gets added slight shear forces as the main and inner tires rub together. I must admit that I am quite sensitive to such things, so getting back up to air pressures of 1.25 bar/18PSI it’s largely noise-free. Only when I have mounted another HR tires shortly before finalization of this report (the intro information soon) was the noise almost completely gone. Obviously, the effect is not only the surface of the inner ProCore tire, but also in combination with the outer tires used by you. Apparently there are combinations that are better natured than others.
I have already contacted Schwalbe to find out how much of this is an isolated case or whether there is need for improvement , but because of the current summer holiday period, it may still take a little bit to get this answer.
No matter if ridden at 1.0 bar or at 1.25 bar, I have never experienced any defect. loss of air or any other issues, no matter how hard I tried. For rim manufacturers, this could mean that they could start designing and building the rims differently because requirements for stability and snake bite protection now are quite different.
TIRE STABILIZATION:
However, what is even more important to note is that the outer tire by Procore is only stabilized to some extent. Especially in off camber situations or fast cornering on hard ground, the tires flex quite noticeably at very low pressures (for me that is under 1.1 bar). For some riders this may even feel a bit spongy and sometimes unstable depending on riding style and air pressure. What the inner tire does though is prevent the tire from folding over all the way to the rim’s flange. However, in order to push the tires this far, it already requires a lot of courage and driving skills … or absurdly, extremely low pressures.
So in fact Procore actually prevented the tire from completely folding over, but still leaves it to flex more pronouncedly that some may tolerate or like. Especially after jumps or drops with not so perfect landings , I noticed this again and again. There it feels a bit like the tires would simply wipe out but they always bounce back to stability.
The lateral stability remains an issue with Procore when it is running at those low pressures.
It seems that Procore is very good when combined with wide rims and their natural ability to stabilize the tire at low pressures. Possibly we will try a combination with a narrower rim during the long term testing because the AMERICAN CLASSIC Wide Lighting definitely belongs to the species of very wide rims.
Note: Mind you, these experiments have taken place only on rooty forest trails. It may well be that outer or inner tire pressures need to be adjusted when ridden on rocky ground and in a more aggressive riding style even more than the previous ridden pressures. So far, there was no situation in which more than 4 bar in the inner tire would have been necessary.
Runflat tires:
Sabotage! – Letting air out of the main chamber to test the emergency running properties of the inner tire.
So much for the niceties in the riding experience with Procore, but how do does it work for real emergency running? If you have, despite all your precautions and set-up, say from casing damage, a total loss of air in the outer tire?
How about at zero PSI?
Simulated flat – with no actual defect I had to let all air out of the main chamber and test the emergency running properties of the inner tire.
For me this never happened accidentally, so I made the experiment on purpose and in the middle of a ride, let the air completely out of the outer tire.
And so I, with a greta deal of doubt, rode home. The first thing you notice is the immense rolling resistance. Even downhill you have to still work hard to move forward and uphill’s are painfully hard. Riders who seeks a really hard training experience…here you go!
On the other hand, you can actually continue alone on the filled Procore system – although with great effort and a squeaking noise as a constant companion, but you can still drive with it even over difficult terrain. It takes a bit of care and skills over roots or other obstacles. Once the path is steep though, the outer tire starts to slip uncontrollably over the inner tire which feels very shaky for the inexperienced driver. I stress especially the unskilled rider factor, because you get used to it or at least partially so over a bit of riding.
Still this was a very positive deal: Even after 10 km of riding where I tried the system deliberately to find the limits (including drop offs and oblique root passages – see above), I was not able to break loose the tire from the rim.
Even on trails like this you can ride only on the Procore inner tire…with some care.
My verdict on the emergency running properties is as follows – yes, they are definitely there and are truly remarkable when compared to anything else out there, but they are and will remain to be purely emergency properties. If on a ride I were confronted with a puncture the sealant no longer would be able to repair, I would be guaranteed to get home riding. However, the necessary effort to keep moving and the very unstable ride are something I don’t really care for. Ergo – if there is only the slightest chance that switching to a normal tube would also get me home (say the casing is not hurt too badly), then I would prefer this route and insert a tube, rather than keep on riding on the Procore inner tube alone.
The state of our current test still proves that SCHWALBE’s Procore is a huge step in the right direction for a contemporary tire system – increased safety margins and rollover behavior and the comfort and traction are just amazing. However, there are limits – for example when in run flat mode and the low pressure induced squeakiness. This shows that even here there is potential for improvements, but the very positive, basic properties of Procore needs very little tweaking. Stay tuned and we will test the system even further for you.
RIDE ON,
c_g
Note: All the components shown here were sent for test/review at no charge to Twenty Nine Inches-DE. We are not being paid nor bribed for this review and we will strive to give our honest thoughts and opinions throughout.
Nice read!
In case of a big puncture on the trail: How much time and effort does it take to remove the system from the rim?
I never run front and back pressures the same.
1.1 bar is my normal front pressure on Wide lightnings and then 1.7 rear.
So, taking the weight and cost and potential drama from a big camel thorn into consideration ( is there sealant in the core?), this does not seem to be for me.
I have been looking into procore for my rigid 29er in order to run lower pressure and increase comfort – I am old. I understand it is made for dh. Right now I can run 16-18 psi on my 2.4 flow wheelset. Would the schwable set up be an improvement or just overkill? Reading some of the other comments about the system, it seems it would work better if the inner tire was tubular. I think some other company used the system on bicycle first, with tubular.
@LarsV: I have never tried this in the field but I would say it should take not much time. I would say 5 min tops. Basically it is no more than deflating both air chambers, get the outer tire off completely and then take the inner tire out. But keep in mind that the timer greatly depends on the fit of the tire on the rim – if it is ver tight fitting, it may be more difficult.
@Anonymous: You are a very special rider if you run these pressures on your rim and don’t suffer from problems. Even with wider tires and them set up tubeless, 1,1 bar seems awfully low and 1,7 seems rather high. If these pressures are correct, you would greatly benefit from at least running Procoe on the rear – more comfort, control and traction and still a very safe set up. The weigh penalty would also be only half ….
For me the 1.1 to 1,25 bar pressures would be unattainable safely if I had not the snake bite protection provided by Procore.
If the weigh penalty and extra work is something you find acceptable, well this is something I cannot judge. To me and at this point I see the benefits outweigh the disadvantages greatly.
@Gustav: If you already run such low pressures safely and with no negative effects, I would think you could go even lower with Procore – after all its working range is said to be 0.8 to 1.5 bar. How would that sound to you?
The big benefit of the inner tube being open, ist that it can be run on a larger variety of rims and still secure tires best possible on the rim. What exactly would be better if the inner tire were a tubular?
If you went with a tubular innre tire, it would need to have just exactly the right diameter to work as well. There is a system called DEANEASY, that goes with a tubular inner tire, but it can only accommodate rims between 21 to 23 mm inner width. Procore starts at 24 mm with no upper limit stated so far.