A guide to road bike disc brakes

The latest development in road cycling technology is disc brakes, and like helmet use and Rapha clothing, opinion is divided by them. There are both pros and cons associated with using them. To help you decide whether they’re right for you, or help when debating, read on.

Disc brakes have been around on mountain bikes for years and have seen huge leaps in development in that time making them the brake for off road use. Their switch to the road has been a very slow one despite their proven ability off road but in the last few years this has rapidly changed. Manufacturers are now embracing discs and the lessons learnt from mountain bikes are very quickly being adapted for road use.

What are they?

Disc brakes work in the same way a mountain bike or car brake does. A caliper mounted near the front (on the fork) and rear (on the chain or seat stay) hubs contains pads which push in on the disc which is attached to the wheel hubs. There are two types of system; cable and hydraulic which are explained in more detail further down. Both operate under the same principle, simply pull the lever and the pads are pushed in slowing the bike down.

Why use discs on the road?

There are some very good reasons for using disc brakes on road bike. They offer more consistent braking especially hydraulic versions and are more reliable in the wet.  Buckled wheels aren’t as much of problem as there is no brake caliper for the rim to rub against, good news for commuters and tourers.

Not having a brake caliper bridge on the frame also allows more clearance for wider tyres so comfort comes into it as well. The emergence of bolt through axles really stiffens up the ride, especially up front on the forks. Hydraulic systems are pretty much fit and forget once set up properly with the only maintenance being replacing brake pads in the caliper.

As there is no heat transfer from brake pad to rim, tyres have less chance of rolling or blowing of the rim or even deforming with heat, although this is something you will probably only experience on very long Alpine type descents.

A photo posted by Merlin Cycles (@merlincycles) on


So why aren’t we all using them?

Well for a start the UCI, cycling’s world governing body, doesn’t allow them in bunch races. We’re not going to argue this case but if you do happen to fall on one the heat and sharp edges can cause a nasty injury but then again so can chainrings and spokes.

Some of the big foreign sportives have also recently introduced a ban on disc brakes so make sure you check the rules and their websites for the latest information before travel or booking. Disc brake systems are heavier than a standard caliper set up and like for like equipment level type they’re more expensive.

Hydraulic systems require specialist tools to service and are more difficult to set up, saying that though they are pretty much maintenance free after as already stated. Disc brake pads can also drag on the caliper after long periods of sustained braking and can take a while to cool down. You will also need a disc ready frame and fork as well as disc wheels so you can’t just stick them on any old existing frame set.

Types

There are two types of road disc brakes available; hydraulic and cable, each with their own advantages and disadvantages.

Cable disc brakes

These are the most common types at the moment thanks mostly to the fact they are cheaper to produce and are compatible with any standard cable operated brake lever. They are also easier for the home mechanic to service.

Pros – compatible with standard gear/brake levers, easier to maintain, cheaper

Cons – not as smooth or consistent as hydraulics

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Hydraulic disc brakes

Hydraulics offer the best performance but are expensive, require a dedicated hydraulic brake lever and not as easy to work on although once set up they shouldn’t need fettling with again for a long time.

Pros – smoothness, consistent braking, lack of maintenance required once set up

Cons – more expensive, harder to service, requires dedicated hydraulic gear/shift lever

ktm_rev_disc_road_bike

Can I put disc brakes on my current road bike?

You can only fit disc brake calipers to a compatible frame and fork so unless you have disc mountings already on your frame or fork you will not be able to fit them. If you do have the mountings then you will need to check whether you need flat or standard mount calipers.

Cable discs will work with any cable operated lever but hydraulic discs are only compatible with a dedicated hydraulic lever.

Lastly, you will need disc compatible wheels and here you will need to check if your hubs are six bolt pattern or centre splined for rotors compatibility.

Who should buy what?

For some road riders discs can be very useful.

Commuters – will find many advantages as they can fit wider tyres and wheels are less of a problem if buckled.

Tourers – will also find the same benefits as commuters and will appreciate the greater stopping power if they are carrying greater weight. Hydraulic systems will also require less servicing although if they do go wrong will be harder to fix.

Cyclocross – were the first drop bar riders to adopt disc brakes with considerable success and popularity thanks mostly to less chance of clogging in mud.

Sportive riders – some of the big foreign sportives have banned discs in their events so check websites for latest details before turning up.

General road riding – discs are great if you want to run wider tyres and want more consistent braking in wet weather and aren’t worried about the weight penalty.

Racers – lose out though as discs are not allowed for bunch racing.

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