As modern bikes increasingly feature electronic components we must consider the water and dust resistance of those components, which are rated using the IP system - the "ingress protection" code. Water and dust resistance plays a critical role in the reliability and performance of your bike and accessories - think Shimano Di2 or SRAM AXS batteries and electronic shifting, Garmin and Wahoo GPS devices, power meter cranksets and pedals, lighting systems - or maybe you're even riding an eBike with a battery, display, and motor.
You may see components marked "IP67", "IPX7" and so on - but what do those numbers mean? These are important if you ride in wet or muddy conditions, and especially so if you wash your bike regularly - as cyclocross, gravel, and MTB riders do. Here's what you need to know about water and dust resistance ratings for modern bicycles.
Nothing is waterproof or dust proof
No component can claim to be 100% waterproof or dust proof. The IPxx (IP means "ingress protection") system tells you, at a glance, how resistant a given component is to water and dust incursion - from a little, to a lot.
Just because a component carries a certain rating, does not mean you should push the limits. It's better to play it safe - for example, if a component claims to be resistant to "high-pressure water spray", limit exposure to "low-pressure water spray", and you should be fine.
Many modern devices claim to be resistant to immersion - but that doesn't mean you should deliberately submerge your iPhone to test it out!
The first digit in an IP rating describes dust/debris incursion
The first digit in the IP rating - for example, the "6" in "IP67" - describes the resistance to debris: think dust or dirt, when it comes to bikes. The scale goes from 0 to 6 - 0 being no protection at all, and 6 being the most - almost completely dust-proof.
The ratings for dust and debris incursion are based on the size of the particle. For example, a "1" rated product won't let in foreign objects bigger than 50mm! Not very useful or important in the bicycle world, because a 2 inch diameter rock clearly isn't getting inside your Di2 battery. A "4" rating means that objects larger than 1mm are kept out... getting better and more relevant - but that would still allow particles smaller than 1mm to pass through!
For a power meter, GPS, electronic shifting system, or headlight, we're really looking for IP5 (dust protected) or IP6 (dust proof) ratings to keep out fine particles.
Ever ridden in Moab, Utah and come home with fine red dust everywhere? No big deal if it's in your shoes or inside your handlebar, but we definitely don't want it inside any electrical device, so it makes sense to choose components that carry an IP rating for dust incursion of IP5 or IP6.
The second digit in the IP rating describes water incursion
The second digit in the IP rating describes resistance to water. Let's use Garmin's popular Edge 530 GPS cyclecomputer as an example. It is rated IPX7. The second digit - "7" in this case - means that the device is "protected against the effects of temporary immersion in water."
As with dust and debris incursion, higher numbers are better. A "0" means "no protection", a "4" means protection against "splashing water", all the way up to "9" - "protected against high temperature and high pressure water jets."
Unlike debris and dust incursion, it's defintely possible to overkill the water incursion rating. It would be possible, but needlessly expensive, to produce a bicycle component rated to "8" or "9" on the IP water incursion scale. That type of protection simply is not needed for the normal conditions that bicycles experience.
IP ratings of 6 and 7 are most common in the bicycle industry, and generally are more than adequate. IPX6 and IPX7 rated parts allow you to ride in the rain, splash through the mud, and (gently) wash your bike to clean up afterward.
What does "X" mean in an IP rating?
An "X" simply means "unknown" or "not rated". An "X" is not the same as a "0", which means "no protection." The IPX7 rating used by Garmin on some of their GPS devices, for example, means that the device is rated 7 for water incursion but carries no rating ("X") for dust/debris incursion. Whereas IP07 would mean no protection against dust/debris.
An X IP rating does not necessarily mean that the device is vulnerable to dust/debris; simply that there is no rating. In fact, it is possible that since the 7 rating is so high against water incursion, that resistance to dust and dirt is also implied, due to the design of the device. In some cases, the manufacturer simply didn't bother paying for formal testing.
SRAM's Eagle AXS electronic shifting carries the IPX7 rating as well, and is described by SRAM as "completely water and dust-proof" despite the "X" (no rating) against debris ingress.
Is it OK to pressure wash my bike?
Unless you're in the middle of a muddy cyclocross race, don't pressure wash your bike. Pressure washing your bike is bad.
Cyclocross bikes raced in the mud face some unique, challenging conditions, and there is simply no alternative to pressure washing. In a muddy race, a mechanic might pressure wash several bikes multiple times each in 60 minutes just to keep them rolling! But when the race is over, the real maintenance begins - regreasing bearings, replacing chains and brake pads, and so on. It's not uncommon for pro mechanics to completely tear down and rebuild team bikes multiple times per season, as a conseqeunce of the extreme conditions from weather and pressure washing.
Under normal conditions, you should never pressure wash your bike. This doesn't mean you can't use a hose - just use a nozzle to create a gentle spray, and be careful not to direct water into bearings or electrical components.
What about eBikes?
Riders of eBikes (electric bikes) have some additional considerations. eBike riders may find that each individual component actually carries a different IP rating - the display, battery, and motor might each have a different level or water and dust protection.
Generally, it's fine to ride an eBike in light rain, but think carefully about heavy downpours - and of course, no bike of any type should ever be submerged. Riders should also re-consider transporting their eBike on a car or truck rack in the rain, because freeway speeds can force water into components that would otherwise remain sealed at normal riding speeds. In those conditions, it might be better to transport an eBike inside a vehicle, or cover the eBike with a tarp while driving.
Where to learn more
If you're having trouble sleeping, or just want to geek out over the exact definitations of the IP scale, check out the official text, courtesy of the International Electrotechnical Commission. On that page you can see the precise definitions for each point on the rating scale, which include temperature, pressure, length of time of exposure, submersion depth, and more.