Is Your Spare Prepared?

The team at SILCA has supported more than 400 events collectively over the last few years, ranging from Gran Fondos to IronMan Triathlon to local criteriums and even a World Championship. One issue that seems to plague athletes at every level is the unprepared spare inner-tube. Namely, riders are getting caught out riding wheels too deep for their spare tubes! I cannot count the number of sitting/walking/crying athletes I have come upon over the years who are unable to proceed due to a few cm or even mm of valve stem length.

The Situation

There are many reasons people get caught out with this issue. Mostly, we see that riders pack a spare with standard valve length and then switch to a deeper race wheel on race day without thinking about changing anything. We also see riders who plan to ride one depth of wheel and then swap to a deeper one at the last moment. Other times, an athlete might have a flat and replace that spare with one they’ve just purchased. Lastly, and maybe most common of all, riders often match the valve length of the tube to the rim depth which leaves too little stem exposed for use with most pumps or CO2 inflators.

short valve


Many of the riders we find stuck on the side of the road had intended to just ‘swap’ the valve extender. But there are many problems with this, not the least of which is that during an event like an Ironman, neither your brain, nor your fingers will be working at their peak potential. Dropping or losing the little tool, breaking the extender, having it be corroded to the valve stem, etc. will put an end to your day. If you are already stuck, swapping an extender is completely reasonable to do (we recommend carrying an extender tool with you at all times as well as keeping the extender on your spare), but this should be a backup, not a primary strategy.

The Solution

The solution is to buy or prepare your spare tube with a long enough valve or valve extender that it is AT LEAST 15mm longer than your deepest wheel.

I look at it this way:

Valve that’s way too long for your rim = Looks funny

Valve that’s too short for your rim = You’re walking

Implementing the Solution

Take your deepest rim depth and add 15mm to it, THAT’s the minimum valve stem length you need.


Rim Depth


Example: you ride ENVE 7.8 Clinchers. Your front rim is 71mm deep and your rear is 80mm deep. You need at least 80+15 = 95mm of valve stem to guarantee that you can use any pump OR CO2 inflator.

So if you buy a light butyl tube from Continental, it has a 47mm valve stem. You need a valve extender that it AT LEAST 50mm long for your spare.

The Vittoria Latex tube has a 51mm valve, so the SILCA 45mm extender would be a just right fit!

You find a generic butyl tube at a bike shop with 37mm valve (used to be the most common length) you will need AT LEAST a 58mm extender

 We could go on with the examples here, but you get the idea. Our dream is to never again find a rider on the side of the road at an event who is walking their bike despite having a functional tube AND functional inflation method, yet doesn’t have enough valve to connect the two. Go long, seal it up in whatever you carry your spares in, and never worry about it again.


To Sum it Up

  • Prepare your spare tube with a valve that will work in your deepest wheel
  • Carry a valve extender tool with you also (just in case)
  • Do NOT be tempted to swap your spare out for a single event, even if doing so might save you 3 grams
  • If you are using a disc wheel for your event, carry 2 tubes, one the right length for the disc and the other the right length for your deepest wheel.

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