GCN Tech Clinic: Hanging your bike, wind noise and worn rims

How do I know if carbon rims have become too worn?

Many of us out there are still happy riding around on road bikes equipped with rim brakes rather than the newer trend of disc brakes. However, one of the disadvantages of using rim brakes is that they actively use the rim surface as the braking track. Through the nature of braking, this will slowly abrade away the surface of the rim, so it is important to keep an eye on how worn your rims are.

The most important thing to look for is the consistency of the rim profile, as it is possible that the centre of the brake track will wear at a higher rate to the edges. You want to ensure that the braking surface remains flat and does not become concave as this will greatly affect the strength of the rim.

Unlike on aluminium rims, carbon rims do not feature any wear indicators. If you are ever in any doubt, have your local bike shop assess the rims to give you an answer on their condition.

Will hanging my bike up mess with my hydraulic brakes?

The short answer to this question is no. As all hydraulic brake systems operate as a closed system, the orientation of the bike will not affect the performance of the brake. The caveat to this is if there is any air in your brake system.

If there is air present in the system, by hanging the bike up you will allow the air bubbles to rise to the top, and if this happens you may need to pump your brakes a few times to flush the fluid back into the brakes. If this does happen, it could be a good time to look at performing a brake bleed to purge any air out of your brakes.

Another hack for maintaining good braking performance if you hang your bike up is to put rubber bands around the lever and the bar to lightly hold the brakes on - this will remove the need to pump your brakes up after getting your bike down and ready to ride.

Can you put road tyres on gravel rims?

There are a few factors that need to be considered to answer this question and it isn’t quite as simple as a ‘one size fits all’ rule. All tyres are designed around an optimum rim width.

Typically, the wider the tyre, the wider the rim needs to be to correctly hold the tyre's shape. When looking to fit road tyres on to a gravel-specific rim you need to decide firstly what width tyre you would like to fit, and also what the internal rim width of the wheels you are looking to use actually are.

Most tyres will come with a recommended rim width range that they will work best with - if a rim is too wide for the tyre you run the risk of it not seating it correctly or not holding the rim with enough force to be secure. The best thing to do is to check with both the tyre and the rim manufacturer that they are compatible.

How long does a waxed chain really last?

Waxing chains is a very hot topic at the moment, with notable performance gains but also gains to be made in the longevity of the chain. As the wax is dry once applied, it doesn’t attract the dirt and grit that a typical wet lube would. In these kinds of conditions, how long can you expect a waxed chain to last?

Luckily for us, Alex has put this to the test recently, riding in typical British summer-time weather of plenty of rain with added road grit for good measure. After 100km of riding the chain needed a wipe down but other than that, it was good to go for plenty more riding. Inspecting your waxed chain after each ride is a good way to monitor if it requires any additional care.

How to deal with wind noise whilst riding

There is nothing quite like the sensation of riding along with the wind in your face and the freedom that only a bike can bring. However, that sensation will quickly diminish if you suffer the relenting sound of wind noise as you ride. There are a few things you can do to try and ease the harshness of the wind, but to an extent, this comes as part and parcel of riding at faster speeds.

The best way to ensure wind noise is kept to a minimum is by ensuring that your helmet straps are tight and lay flat on the sides of your face. It is surprising how much wind noise can be caused by the turbulence of helmet straps. Another thing to look at is how your clothing fits - if it is loose or doesn’t quite fit to your body well, this can flap in the wind and create lots of noise, so ensuring that all your kit fits well will also help reduce the noise of the wind.

How accurate is the calories burned function on my computer?

The more data you can feed into your computer, the more accurate this will get. On its own the calories burnt function is a very rough estimate based on your weight, and the speed and elevation of your ride, however this assumes a lot of variable data. By using heart rate, or - even better - a power metre, you will start to get a better idea of the effort you are putting out.

Power is an absolute marker of an effort as one Watt is the same as one Joule per second. This means that power data will give you a far closer idea to the calories burned, but this still assumes human efficiency of around 25%. Human efficiency is something that will vary from person to person and small variances in this will extrapolate out to large sways in expended calories.

As a rough guide, by using the built-in calorie function on its own there is the potential for up to a 30% margin of error in calculated calories. When paired with a heart rate monitor this error will reduce, and with a power metre will fall to around 5%. It is always good to take calculated calories with a pinch of salt and use them as a rough guideline rather than a precise number to refuel by.

Can my chain be completely worn after 1,000km?

The drivetrain on a bike is a consumable item with chains subject to wear, and so too are the cassette and chainrings. One of the best things you can do to reduce premature wear is to measure chain wear with a chain checker. It is better to replace the chain as it starts to become worn, rather than running the chain until it is completely worn out. By doing this you will prevent the need to replace your chainrings and cassette every time.

It is unlikely that after 1,000km of riding a chain will go from new to completely worn, however it isn’t impossible. Mountain bikes are particularly susceptible to this, but riding around in dirty and gritty conditions can accelerate chain wear substantially so keeping your chain clean, or even using a wax lube, can help prevent dirt grinding away your lovely new chain.

Fitting a new chain to old components is also a sure-fire way to experience premature wear. If your chainrings and cassette are towards the end of their life, it is important to replace them at the same time as fitting a new chain. Fitting a new chain to tired old parts will cause the chain to wear to match the profiles of the existing components, causing the chain to become worn very quickly.

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