While mountain bikes have no sexy exhaust sounds, a good-sounding bike is still part of the fun of trail riding. In fact, the noise while riding is an aspect that has gotten more attention in recent years. A comment I regularly get on my YouTube videos is that my bikes are so quiet and how I managed to do that.
If you ever watched a mountain bike race live or watched raw videos, you probably noticed there is something very distinct about professional riders’ bikes – apart from paint jobs and sponsor decals. While visually flashy, they are very discreet acoustically.
This is done by design. In fact, a lot of the pro mechanics’ effort is spent on getting the bikes as quiet as possible. This is beneficial for concentration, trust in the equipment and also for being able to hear how the bike is performing in the moment. Tire and suspension noises are important acoustic cues.
And then there are background noises no rider wants to hear. Let’s get to know what those are, how they occur and how to reduce those noises.
What makes a mountain bike loud?
Chain slap, clanking cable hoses, bad gearing, damaged bearings, and loose bolts are among the main reasons why your mountain bike may make loud noises like clunking or creaking. Modern mountain bikes are designed to eliminate those from the factory, but most of those new noise-canceling features can be upgraded aftermarket on any bike.
In this article, I will go into how to reduce normal bike sounds that naturally occur while riding. There are also noises resulting from lacking bike maintenance like creaking, clicking and scratching noises.
For more on stopping those, check out this article.
Looking at it at the most basic level, a bike is basically a frame with a bunch of components bolted to it. Each connection, intersection and contact point has the possibility to become loose, dry, and damaged while other parts are required to move during normal trail riding. With that perspective, not a lot has to go wrong for a mountain bike to be loud, but conversely, a lot has to be right for it to be nice and quiet.
This is how to make your mountain bike quieter:
Clunking and banging sounds result from bike components banging against each other on another bike part. The biggest culprit for clunky noises is by far the chain. And this can be for many reasons, all of which can be avoided.
Reduce chain rattle noises
A big part of mountain biking is hustling down rough trails, that give the rider and bike a good shake. Watch some slo-mo footage and you’ll see how the chain gets tossed around, banging against the chainstay and seatstay (the rear part of the bike frame above and below the chain).
Shorter chain for less slack
The amount of can be reduced by increasing the tension on the chain in two ways: reducing chain length and/or increasing the pull by a clutch derailleur. The former is free and only requires a chain tool, while the latter can get pricey depending on the drivetrain.
A good rule of thumb for chain movement is 2 finger-widths up or down while on the largest gear. Any less than that is definitely too tight and risks damage. In fact, new chains come too long for most bikes and need to be reduced in length before replacement in any case.
Rubber chainstay protectors
With a reduced range of movement for the chain, there is still no way to prevent it from slapping onto the chainstay, the part of the frame right beneath the upper chain line. Luckily, this common problem is solved extremely easily by covering that part of the frame with rubber.
They come in various shapes and sizes. I personally got simple adhesive rubber tape on the cheap end of the spectrum while solutions like STFU or Velocity Hucking Systems with air pockets offer the best noise-canceling for a higher price. Generally, softer is better here. Don’t go for thin or plastic frame protectors.
The free, but not-so-pretty DIY version would be the old inner-tube-wrapped-around-and-held-on-by-zip-ties hack.
Bash guards are primarily designed to prevent lateral chain movement and the chain ring from hitting rocks and roots. With a lower guide roller, they also increase chain tension and reduce chain slack by pulling it up by roughly an inch.
Proper chain length is something to keep in mind with a chain guide like this. It needs to be a couple of links longer than without one.
Also, a lower guide roller is not a stand-alone part and has to be mounted to an ISCG chain guard, so it’s an expensive and little impactful method to reduce noise if that’s your main focus.
Stop cable rattle
The other main source of clunking sounds are the shifter cable and brake hoses. Even more than with the chain, restricting movement is the name of the game here as the options are more limited for cable management.
With internal cable routing, the options are somewhat limited. And that cable canal is actually the loudest part on my downhill bike, where I’m unable to eliminate the rattle inside the frame. So, outside cable routing may be preferable for reducing bike noises.
Shorten cable hoses
The same principle as with the chain slack applies here. The shorter the cable hose, the less room it has to flap around. And the hoses too need to have at least a little slack so they don’t bend in sharp angles and also allow the handlebar to turn in its full range of motion.
Cables and hoses can be cut with simple, sharp wire cutters. Universal pliers won’t do here. But keep in mind: measure twice, cut once.
Turn the handlebar all the way from one end to the other to check the cable length from the head tube to the handlebar. Along the frame it can be as tight as possible, it just has to allow the rear suspension to go through its entire travel.
Attach cable hoses to each other
A great way to prevent the hoses to clap against each other is to combine them straight up. There are rubber connectors, that come with some bikes. But those tend to move around or not hold the cables that reliably.
A method many riders use is to put regular duct tape around brake hose and shifter cable on the same side, that go parallel to each other. I also tied the brake hoses together right in front of the stem, where they go on top of each other – a great place to bang against one another.
Finally, there’s the rubber side of the house again. Especially with internal cable routing, there is always a little wiggle room for the hose inside the channel. While there is no reliable way to eliminate that inside the frame, rubber grommets help on either end of the cable canal.
It may not look like much and can be cumbersome to install aftermarket, as the brake or shifter system needs to be disassembled to be able to pull out the cables. But the difference is well noticeable. Maybe combine such an upgrade with another maintenance job. That’s not something I would do on its own.
Other banging noises
Bolt checks should be part of the regular maintenance schedule. A couple of bolts should even be checked before or after every ride. Namely: Axles, stem bolts, and linkage bolts. The seatstay clamp, grips and brake levers aren’t a bad idea either but, not quite as susceptible to loose bolts.
No noise-reducing accessories can help you when you ride with loose bolts. It’s loud and dangerous for you and the bike all at once. For a quick tune-up mid-ride, I always carry a multitool on trail rides in my hip pack or backpack. It’s rare but my axles can get quite loose on a full day of rough downhills.
One thing you can’t change on the bike, but is definitely worth considering is how the frame’s rear end is designed. What you want is a stable, relatively simple design with not so many moving parts and slim tolerances. Any imperfections in design or movement in the bearings will lead to quite some movement in the rear wheel accompanied by some annoying noises.
The rear suspension design is why I didn’t go for the otherwise great Canyon Sender downhill bike but the YT Tues. The Canyon bikes pre-2022 had quite loud rear ends, that only became increasingly louder with more bearing wear.
So, no matter which suspension design philosophy the manufacturer employs, the lesser moving parts, the better. Also, wider rear triangle designs generally are more stable and bulletproof.