Friday, August 14, 2020

Cervelo Aspero: Tubeless Setup with Schwalbe Tire Booster

One big advantage of using wide gravel tires is the ability to run low tire pressures. With a low tire pressure, the tire can conform easily to the uneven terrain, generating good traction and improving ride comfort.

However, if you are using inner tubes, there is higher risk of getting a pinch flat when running low tire pressures. This is due to the softer tire which can bottom out easily when hitting sharp edges or landing heavily. When that happens, the inner tube will be pinched between the tire and the rim, creating the distinctive "snake bite" marks of a pinch flat.

This happened to me while riding off-road on the previous Canyon Endurace, using the 32 mm wide Panaracer GravelKing SK tires. I was not paying attention and deviated off the path, and although I managed to recover without crashing, I suffered a rear tire pinch flat when the tire bottomed out on the edge of the road. If I remember correctly, the rear tire pressure was about 38 PSI.

Therefore, when I went for even wider gravel tires on the Cervelo Aspero, I wanted to try tubeless tires as well. The WTB Venture 47 tires are tubeless ready, as with practically all decent gravel tires nowadays. With a tubeless setup, there is no inner tube to pinch, which allows low tire pressures to be run safely. This is seen on many MTB where low tire pressures and tubeless setup is commonplace.

One tricky part of tubeless tire setup is the seating of the tire beads onto the rims. As there is no inner tube to push the tire from within, a quick blast of air is needed to push the tire onto the correct inner edge of the rim. If the blast of air is not large or fast enough, air will just leak out from the gap between the tire and the rim.

The solution is to use an air compressor, or for the home mechanics, a canister to store and discharge the compressed air quickly. It is a bit like a giant CO2 inflator, just that the air pressure is lower, but with much greater volume.

There are many such air boosters on the market, specifically catered for seating tubeless tires. I made my choice based on good reviews on this Schwalbe Tire Booster. Let's see how it works and how effective it is.

Schwalbe Tire Booster

Comes with a metal tank with a hose attached, a velcro strap and the instruction manual. The velcro strap is for attaching the air tank to the vertical cylinder of a floor pump if needed.

A Presta valve at the top of the tank allows the tank to be charged, by pumping it up with a normal floor pump.

Once the air inside the tank is of sufficient pressure, you can open the valve to release a large amount of air quickly. This will seat the tire onto the rims properly.

Pump head at the end of the rubber hose can be switched between Schrader or Presta valves.

Before using the tire booster, the rim needs to be prepared. A layer of tubeless rim tape is needed to seal the rim to prevent air leakage. Nowadays if you get a new wheelset, tubeless rim tape is usually already installed. A tubeless valve is also needed, as shown below.

Tubeless valve to be used for tubeless tire setup.

A Presta tubeless valve has a removable core, so that you can push in large amounts of air quickly, and also to inject sealant into the tire.

To charge the air tank, just connect the pump head of your floor pump to the Presta valve at the top of the tire booster. Pump it until around 160 PSI, which is pretty high. This is to ensure sufficient air pressure and volume to seat the tire later.

Once the air tank is charged up, and the hose connected, get ready to turn on the valve!

First try, not successful. Some sections of the tire (top left) is not seated onto the rim. This is because I did not charge the tire booster to a sufficiently high air pressure, which is around 160 PSI.

After charging the air tank again, which is super tiring for the arms, I gave it another go. This time, the entire tire was able to seat fully on the rim.

At this point, the tire beads are already resting properly on the rim. However, if you try to pump up the tire now, you will still have air leaking from the multiple gaps between the tire and the rim. The most tiring part of seating tubeless tires with the air booster is charging the air tank up with a floor pump.

The next step is to add sealant to this tubeless tire setup, so that the sealant can plug and seal the gaps that are invariably present. If you do it correctly, it is actually not messy at all. I read many how-to-do guides and tips on tubeless tire setup, and now I'm going to try it for myself for the first time. If you have a friend who can show it to you, that would be best.

Stan's sealant, one of the best in the business. Might as well get a big bottle instead of a small one, in case I screw up.

Instructions written at the back of the bottle. As you can see, there are different methods to set it up, which mainly depends on your type of valve.

Together with the bottle of sealant, I got the Stan's sealant injector as well, which is basically a syringe that screws onto the valve.

The syringe injector should make it much easier and less messy to inject sealant into the tire.

However, I found that the Stan's injector does not screw on properly to the valve at all. I tried with a few different valves, and they all had the same problem. I think there is a problem with the screw thread on the injector.

Luckily I had not started with the sealant, so I could put away everything and continue another day, until I got a properly working injector syringe.

I came across this sealant injector by KOM Cycling, which is slightly different. Check out the details below.

Sealant injector by KOM Cycling, which works differently from most other sealant injectors.

Contents of the KOM Cycling sealant injector. There is even a valve for controlling the sealant flow if needed.

What's different is the rigid tube shown on the left side, which is narrow enough to go INSIDE the valve, instead of around the outside. This allows sealant to be injected AND also removed if needed.

Usage method is pretty much standard, which is to suck up sealant from the bottle first. The metered syringe makes it easy to measure the amount of sealant that is required.

Now, insert the syringe through the valve, so that the sealant is dispensed directly into the tire, bypassing the valve area. This is supposed to reduce the chance of the valve clogging up.

I never liked this kind of valve core tool, as you can only engage the valve core at 180 degrees apart, which means the spokes always gets in the way when tightening or loosening the valve core.

This smaller valve core tool works much better, as you can spin it around easily. Remove the valve core so that the rigid tube of the syringe can be inserted.

For this tire width of 47 mm, a sealant volume of 60 to 90 ml is recommended.

Insert the tip of the rigid tube into the open valve, and inject the sealant!

As the rigid tube goes through the valve, the sealant does not cling to the inside surface of the valve. Injecting the sealant was easy and mess-free with this tool from KOM Cycling.

If you ever want to remove sealant from the tire, this tool makes it possible, as the rigid tube can reach all the way to the bottom of the tire, and suck out the remaining sealant. It can also be used to measure the amount of sealant remaining, and top up just the necessary amount.

This sealant injector from KOM Cycling is highly recommended, if you want to set up tubeless tires with sealant easily and without mess.

A side benefit of using sealant instead of inner tubes is some weight savings. Each of the Schwalbe SV21 inner tubes for wide 650B tires weigh 200 grams. If you substitute it for a tubeless valve (< 10 grams each) and 60 ml of sealant, you can save around 130 grams per wheel. In other words, a tubeless setup is lighter and more puncture resistant (small holes are sealed automatically), although setup might be more troublesome.


Take note of the additional 500 grams of weight for the gravel setup, compared to the road setup.

The table above shows the weight of my Cervelo Aspero, with the WTB Venture 47 tires set up tubeless. The weight difference from the road wheelset has been reduced from almost 700 grams more, to just 500 grams more. A weight loss of 200 grams by converting to tubeless.

I was pleased to note that this tubeless conversion worked successfully, without making a mess with tire sealant. With the correct tools, tubeless setup is actually pretty easy.

The ride quality with the tubeless setup is instantly noticeable, with it being more plush compared to using inner tubes. At the same tire pressure (eg. 30 PSI), the tubeless setup is definitely softer. I guess the tire deforms more readily without the extra layer of inner tube inside. I have heard that rolling efficiency with a tubeless setup is better, which will be a good bonus as well.

No comments:

Post a Comment

Every comment is moderated before publishing due to spam bots. If you don't see your comment yet, it is likely that it is currently being reviewed. Thank you for your patience!