Types of Bike Tire Tube Stems
Schreader and Presta Valves: Each With
Their Own Advantages
A bike tire tube stem is the small metal valve on a bicycle
tube that allows you to attach a pump and fill up your tire
with air. The tube stem typically comes in two different designs,
each with its own advantages and disadvantage.
 Schraeder
Bicycle Tube Valve:
These valves are also spelled as "Schrader" or "Shrader"
so don't let that throw you off, they are all referring to the same
valve that you are familiar with on a standard car tire. I has been
around for a long time. A lot of less expensive bikes are still
using these on their bike tire tube. Stem design is quite bulky
though, so newer bikes especially road bikes with narrow rims, have
reinvented the tube stem with a much slimmer profile.
All schraeder bike tube valves have a removable core that allows
the insertion of tire sealant (ie. a chemical that resides in the
tube to seal small puncture holes on the fly). Be careful here though
as some tire and tube manufacturer will void their warranty if a
sealant is used, so ask first.
A Bike Tire with a schraeder tube stem has a couple of advantages:
- Readily available, when you get caught needing a replacement
- Can be filled at the local gas station without having to remember
the adapter fitting.
- Easy to remove the valve core and fill with sealant
- More rugged in design, thus more forgiving when filling and
a better choice for young children that are choosing to fill their
own tires.
That being said they do require more pump power to fill. The
air flow must first be able to lower the spring holding the valve
closed before it can begin filling the tire itself.
Presta Bicycle Tube Valves:
 This
is the slimmer newer redesign of the tube stem. A Presta Valve requires
a smaller hole in the bike rim causing less impact on the overall
strength of the rim. The older Schreader valves with their larger
stem diameters required manufacturer to stay with wider rims to
maintain stiffness and strength around the port hole. A presta bicycle
tube valve solves that problem offering greater flexibility in design.
For this reason presta valves are typically used on higher end
mountain bike rims and on all slim line road bikes. For competitive
bikers looking for every edge, these valves are also much more aerodynamic
and are less likely to unbalance the wheel.
Some presta bike tube valves do have a removable valve core, which
is necessary if you would like to use tire sealant product and fill
it on your own. The word on the street though is that these double
screw-in valves have a bad habit of coming loose and require a set
of pliers for onroad repairs. Thus I'd avoid the whole story by
buying prefilled self sealing tubes or stay with the regular ones
and use tire liners for puncture protection.
 To
fill a tube via a presta valve, you must use an adapter in order
to use a common gas bar pump. This adapter can be left on the rim
if you are likely to forget it at home and don't usually bring a
pump with you on your rides. But this may kind of counteract some
of the advantages of using a presta valve by adding more weight
to the outer circumference of the wheel and increase the power needed
to initial accerleration.
Presta valves do require less effort during inflation because there
is no spring holding the valve closed as with Schraeder valves.
They are better at holding the higher pressures found in road tires,
and less prone to leaking.
It is important to remember that the types of bike tire tube stem
can affect robustness. A presta valve is much more fragile than
a Schraeder valve and therefore extreme care must be taken during
filling so that it does not get snapped off. Carrying a replacement
tube is essential. It is impossible to fix a tube stem, and no fun
if you have to push your bike five miles out of the bush.
More Articles of Interest:
A Bicycle Tubes Design
|
