Uniquely SILCA: The Leather Washer
History
Leather cup washers were used in the first pumps that SILCA produced in 1917 and are still used in all of our floor pumps and frame pumps today. Since 1947 we’ve used the same supplier in Milan, Italy who cuts them from the excess material left over from the production of high end luggage, hand bags and luxury Italian cars. All SILCA leathers are produced from the highest durability materials available, using off-cuts and remnants which would otherwise be discarded.
One of the defining characteristics of SILCA throughout our 100-year history has been the continuous search for innovations and improvements to our products, down to the smallest of details that go into them. Our modern line-up of pumps for example pay homage to their original designs (some of them dating back more than 75 years) yet are built using modern engineering practices, materials and standards. Yet through all of the innovations and changes we’ve gone through as a brand, there are some things that will never change. A great example of this is our use of the leather washer inside of all of our pumps since 1917.
General Thought
As something that is typically used before every ride; durability, efficiency and overall experience are key design goals of all of our pumps. An accurate gauge, quality chuck and stable base go a long way towards achieving these goals yet the internal components of the pump are by far the biggest determining factor in regards to overall performance. It is the internal components after all, that work together to create the seal, which then builds pressure inside the barrel that ultimately ends up inside your tires. Overall performance then depends heavily on this internal system and we’ve yet to find anything more durable, consistent, efficient or pleasurable to use than full grain leather.
Leather Durability
The biggest issue with most pumps is that they just don’t last long before they begin to not perform as well as they did when they were new or they break completely. In most cases, the issue is that there’s no longer a proper seal within the barrel to push the air through the system and into the tire. The most common system used to create the seal is a rubber O-ring on the end of the piston. Pressure is created by the O-ring making contact with the inner walls of barrel, which then pushes air through the system as the rider moves the handle up and down.
The issue with O-rings is that most aren’t designed to deal with the friction, heat and airborne contamination experienced within a bike pump. Unlike a suspension fork or shock which uses o-rings completely sealed and bathed in oil, the pump inhales air and all of its contaminates with each stroke. It only takes a single particle of grit or sand to enter the pump to begin damaging the O-ring. Once the O-ring develops a nick or tear, then the seal becomes less effective and therefore is no longer able to push the same amount of air. Over time, the exposure to heat and pressure will cause nicks and tears in the O-ring to grow and ultimately fail the ring.
Our leather washers on the other hand are extremely durable. Formed using steam and pressure, each gasket is a full 3 mm thick, which makes them resistant to fatigue and damage. Each gasket is hand cut and formed by the same leather vendor in Milan, Italy who specializes in producing high end luggage. Since 1947, our supplier has cut SILCA washers from the off-cuts of luggage production, allowing us to provide washers made from some of the most exclusive, expensive, and durable leathers, while also saving these materials from the landfill. The end result of this has been a legacy of obsession by Professional Mechanics.
Every year, we hear stories from our professional mechanics about how much sand and dirt ended up in the barrel at races like the Tour of Qatar or some of the Spring Classics yet the pumps performed flawlessly. It’s stories like these, along with a century of use, that give us extreme confidence in the leather washer’s ability to keep your pump performing flawlessly for decades.
Pumping Efficiency and High Pressures
Another common complaint with a lot of pumps has to do with pumping efficiency and the inability to reach high pressures as the pump ages. Again, this issue is most often traced back to the use of a rubber O-ring to create the seal.
You may not realize it, but there’s quite a bit of heat being generated inside of a bicycle pump as a result of the compressing air to high pressures. As the temperature increases, the diameter of the barrel will inevitably increase (ever so slightly) as well. The problem with a plastic or rubber O-ring in this situation is that it doesn’t expand in diameter with the pump barrel the way leather does so there’s going to be slight gap between the two and therefore a loss of efficiency.
The leather cup washer on the other hand is pushed outward against the tube wall by the air pressure beneath it. This makes the system 'self compensating' and the leather could easily grow up to 5mm diameter if it needed to, so the fraction of a millimeter of tube growth goes relatively unnoticed by the leather seal.
Experience
Cycling is about recognizing those little nuances that form together to create this beautiful mosaic of emotions that we all refer to as ‘the cycling experience’. The sound of a perfectly tuned drivetrain, the euphoria of reaching a summit, the feeling you get atop a perfectly balanced bike to name a few. Can inflating your tires before the ride be synonymous with these experiences? We say it can.
Simply put, we’ve tested out a lot of different alternatives and nothing comes close to the experience you get when using a pump with the leather cup washer. On multiple occasions, we’ve set up a blind experiment where we have pumps with the leather washer and ones without and asked people to choose which one they like better. In three years of conducting that experiment with hundreds of participants, we’ve never had anybody choose the pump that didn’t contain the leather washer.
The leather washer feels better because of how it interacts with the lubricant and leather conditioner on the inside of the barrel. Rather than just push the lubricant around like an O-ring does, the full grain leather washer absorbs the lubricant and leather conditioner, which not only reduces friction more effectively but it also lasts a lot longer. Before the leather washers are installed into our pumps, they’re pre-soaked in a special NFS lubricant for a few days to saturate the leather. After that, every stroke of the pump allows the leather to lubricate the tube walls as it slides along. With a few drops of lubricant dripped into the pump every year, the leather washer will perform flawlessly for decades.
rubber cup shaped washers were superior to anything I have ever used,having said that nothing wrong with using o-ring pumps,so easy to replace those and cheap,but yes the leather cup washers give a nice performance as well,years ago all car and hand pumps had leather cup shaped washers but back then the pump makers made very thin leather washers and there were not great at high pressures due to thin washers,then they made rubber cup shaped washers on portable bike pumps and they were nice ones,I like your silca pumps they are very well designed and nice thick leather washer and you also provide spares and actually show people how to service your pumps,most folk will pay the extra money for a nice pump but it has to tick all boxes,your silca hiro chuck is a very nice design,it ticks all the boxes,cheers
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