DIY Home-made Ghetto Procore Dual Chamber
AndreXTR
Posts: 64
Hi,
I'm trying to develep a ghetto version of Schwalbe procore, and just want to share the ideia to discuss and improve.
I have 26" rims (ERTRO: 21-559) on my DH bike.
1) The idea is to use a clincher road tire, for instance, the Schwalbe Insider (ETRTO: 23-559, price 15€ euros, 210grams, 145 psi max pressure).
+Info:
Schwalbe Insider
2) Make a small hole (6mm) in the road Insider tire. Something like this:
3) Them, drill a 2nd hole in the rim (my rim is cheap and has already 37 holes, 36 from spokes +1 from valve, so no big problem). Put a 2nd air valve in the rim. You can drill the hole in the oposite direction of the original hole to equilibrate the wheel. Seal the valve holes and rim with tape to be tubeless-ready and avoid air leaks.
4) Put a road air chamber inside the Insider tire, like this the photo below. The red plastic peace in the photo is an air guide which allows the air to pass from the valve to the external chamber through the hole. An optional ideia: Use duct tape to wrap around the tube (only just above the 2nd valve and below the Insider tire hole). The ideia is to limit the tube expansion when inflated in that area. By reducing the diameter of the tube in that area (4cm length is enougth) you create a open space that allows the air to flow freely from the 2nd valve to the hole and finally to the external chamber.
5) Install the Insider and the skinny air tube, and then the main tire (in my case a 2-ply BigBetty tire) with liquid sealant. When finished should look like this:
6) The first valve is from the skinny air tube. The 2nd valve fills the air in the Insider tire (but outside of the air tube). So, when inflating the 2nd valve, the air goes leaks through the hole of the Insider tire and inflates the main tire [see point 2)]. A picture from moto tubliss system to help visualizing the ideia:
7) After inflating the main tire (1.5 Bar), inflate the inner air tube (1st valve) to ~ 6 Bar.
I think this system is similar to the first Procore prototype with 2 air valves. The main "problem" comparing to final Procore, is that you have to drill a 2nd hole (not a big deal for me, at least). The second minor issue is that you may need to deflate the insider tube temporarily in order to adjust the main tire pressure (because if the insider pressure is too high, the air from the 2nd valve will not pass-by the tube and escape from the hole in the inner tire). A 3rd minor issue is that you have to seal well the valve's holes to avoid air leaks (probably an o-ring between the rim and the Presta valve nut will work, or something like that). After the Insider tire being inflated to 6bar, there is no big problem for air leaks from the main tire through the valve's holes.
This system will cost about 20 euros per wheel (almost 10-times less than the original). The insider tire costs 15€ in main german online shops. It's cheaper, and I don't think that the disadvantages are very relevant. This system will weigth about 300g (more 100g than the original). However, in my case, with this I will get rid off the DH tube (which weigths 490g).
An alternative method of this, is to use a road tubular 26" tire. The problem of this method is that a tubular tire is not a clincher tire, so it will not fit so wheel in the rims. Also a tubular tire is a bit more expensive.
What do you think ?
PS: Just a initial sketch of the system (with the duct tape trick on step 4 you can inflate the chambers independetly, so you can inflate inner tube first).
PS2: Sorry me english, I'm from Portugal
PS3: Tutorial originally posted on mtbr here
Greetings,
Andre
I'm trying to develep a ghetto version of Schwalbe procore, and just want to share the ideia to discuss and improve.
I have 26" rims (ERTRO: 21-559) on my DH bike.
1) The idea is to use a clincher road tire, for instance, the Schwalbe Insider (ETRTO: 23-559, price 15€ euros, 210grams, 145 psi max pressure).
+Info:
Schwalbe Insider
2) Make a small hole (6mm) in the road Insider tire. Something like this:
3) Them, drill a 2nd hole in the rim (my rim is cheap and has already 37 holes, 36 from spokes +1 from valve, so no big problem). Put a 2nd air valve in the rim. You can drill the hole in the oposite direction of the original hole to equilibrate the wheel. Seal the valve holes and rim with tape to be tubeless-ready and avoid air leaks.
4) Put a road air chamber inside the Insider tire, like this the photo below. The red plastic peace in the photo is an air guide which allows the air to pass from the valve to the external chamber through the hole. An optional ideia: Use duct tape to wrap around the tube (only just above the 2nd valve and below the Insider tire hole). The ideia is to limit the tube expansion when inflated in that area. By reducing the diameter of the tube in that area (4cm length is enougth) you create a open space that allows the air to flow freely from the 2nd valve to the hole and finally to the external chamber.
5) Install the Insider and the skinny air tube, and then the main tire (in my case a 2-ply BigBetty tire) with liquid sealant. When finished should look like this:
6) The first valve is from the skinny air tube. The 2nd valve fills the air in the Insider tire (but outside of the air tube). So, when inflating the 2nd valve, the air goes leaks through the hole of the Insider tire and inflates the main tire [see point 2)]. A picture from moto tubliss system to help visualizing the ideia:
7) After inflating the main tire (1.5 Bar), inflate the inner air tube (1st valve) to ~ 6 Bar.
I think this system is similar to the first Procore prototype with 2 air valves. The main "problem" comparing to final Procore, is that you have to drill a 2nd hole (not a big deal for me, at least). The second minor issue is that you may need to deflate the insider tube temporarily in order to adjust the main tire pressure (because if the insider pressure is too high, the air from the 2nd valve will not pass-by the tube and escape from the hole in the inner tire). A 3rd minor issue is that you have to seal well the valve's holes to avoid air leaks (probably an o-ring between the rim and the Presta valve nut will work, or something like that). After the Insider tire being inflated to 6bar, there is no big problem for air leaks from the main tire through the valve's holes.
This system will cost about 20 euros per wheel (almost 10-times less than the original). The insider tire costs 15€ in main german online shops. It's cheaper, and I don't think that the disadvantages are very relevant. This system will weigth about 300g (more 100g than the original). However, in my case, with this I will get rid off the DH tube (which weigths 490g).
An alternative method of this, is to use a road tubular 26" tire. The problem of this method is that a tubular tire is not a clincher tire, so it will not fit so wheel in the rims. Also a tubular tire is a bit more expensive.
What do you think ?
PS: Just a initial sketch of the system (with the duct tape trick on step 4 you can inflate the chambers independetly, so you can inflate inner tube first).
PS2: Sorry me english, I'm from Portugal
PS3: Tutorial originally posted on mtbr here
Greetings,
Andre
0
Comments
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Looks promising, I would say you need to be carefull on your deisgn of the air guide as it has to perform a few functions
1/ Locate so it's always aligned with the main tyre valve.
2/ Provide a route for air from that valve to the hole in the high pressure tube support (aka the road bike tyre)
3/ Prevent the high pressure tube from being damaged due to interference with the hole in the high pressure tube support
I'm thinking here that you ideally want to lose some weight from road tyre, you need to do some research to find the most suitable, the turbo trainer tyre is a good idea, but I'm wondering if 26x1.35 is big enough.Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.0 -
Hi, thanks for the input.
I think the airguide with the trick of duct tape to strangle the tube will perform that functions. Since that the air tube and the inner tire don't move, the air guide will stay in place (just between the 2nd valve and the hole).
Regarding 3/, I suppose that a small hole in the inner tire with 5 or 6mm in diameter (as depicted above) will not cause any protrusion or damage to the tube. Also because the tube will be wrapped with duct tape in that area, so no big problem.
Finally, regarding the tire size, the original procore seems to have a section width of ~28mm (because it seems to have the same width as this rims, which is a syntace 35 (28mm inner width):
The Schwalbe Insider turbo trainer tire is available at 23mm width (0.9") or at 35mm (1.35). Given that my wheel has a inner width of 20mm, I guess that the 23-559 Insider will be better, or maybe not... Nevertheless, with either tires you get what you want: pinchflat, burping and rim protection.0 -
Deaneasy system (La doppia camera per Mountain Bike). The first using a double air valve!
This system uses a road tubular tire. For non super-wide rims, it shouldn't be a problem!
http://vimeo.com/74188832
Tubeless vs Double Chamber (Deaneasy)
https://www.youtube.com/watch?v=v4aUihSCJe0
https://www.youtube.com/watch?v=9008XIueqGQ
Mounting the system:
https://www.youtube.com/watch?v=mw7BcEV9c5w
https://www.youtube.com/watch?v=P0rDNRzoVEw
https://www.youtube.com/watch?v=KGrz4L9odt40 -
What about using one of those (horrible) solid tyres and then putting a hole through it - something like this one:
http://www.unicycle.uk.com/greentyre-70 ... tAodzzgAGQ
Surely that would be simpler than trying to maintain 2 tubes?0 -
That one is too narrow to work for starters.....also you loose the benefit of the pneumatic spring in a proper tyre.Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.0
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Interesting idea but I think the extra weight might outweigh the benefits for me.
If you need to deflate the inner tyre to before inflating or adjusting the pressure of the main tyre the when you reinflate the inner tyre you increase the pressure in the outer tyre.Transition Patrol - viewtopic.php?f=10017&t=130702350
