New Brake Pads

Servicing the Touring MTB

I'm planning to do some touring in Europe in about 10 weeks from now and over the next few weeks I'll be getting the touring MTB ready. On the list of items to do are:

1. Fit new brake pads
2. Bleed the braking system hydraulics
3. Replace the cassette and chain
4. Replace the bearings in the bottom bracket
5. Fit thermoplastic inner tubes
6. Fit yet another saddle, hopefully one my bottom doesn't dislike!
7. Check and lubricate everything

So, there's lots to do. I want to do as much myself as possible but the fact is, some of the items on my list are things I've never done before so I either have to learn how and get it done or pay a pro.

Today I turned my attention to the brakes. Other items I'll get to over the next couple of weeks.

Brakes

The touring MTB is my only bike which has disk brakes. And previously, I've always had it serviced by my local bike shop. But that shop has long gone and I have gained no practical experience of working with disk brakes, despite owning this bike for 6 years. I know..... it's all horribly shameful :-)

I did some research and the Park Tool video series proved to be a veritable treasure trove of well-explained information on this and many other subjects. In particular, this video was the one that helped with the practicalities of changing brake pads and in navigating the numerous designs that are out there. 

The first thing I gleaned was basically some good news. I bought my Specialized Rockhopper Expert in 2016 and naturally therefore assumed it was the 2016 model. So it was details of the 2016 model I acquired from the Specialized archive and used to figure out what brake pads to buy. But I later realized that somehow I'd bought the 2017 model.... in 2016. I know... it makes no sense except if we assume Specialized released "next year's model" to dealers the year before. Either way, it's definitely the 2017 model and I definitely bought it in 2016! So, I had a small panic that I'd bought incompatible brake pads because the braking system had changed from 2016 to 2017. But panic over.... as described in the Park Tool video, all you need to be concerned about is the shape, dimensions and the material the brake pads are made of. The one's I'd bought are resin (AKA organic) pads and that hadn't changed from 2016 to 2017 and in fact the disks themselves had text engraved in them indicating that only resin pads should be used. That just left the shape and size. So I proceeded to remove the old pads so I could compare them with the new ones. If they matched, I'd carry on and fit the new ones. If not.... 

Inspecting the current pads

I sight checked the current pads and whilst it was clear they had signs of wear and tear, they looked like they had more than 1mm and probably had some life left in them. But given my touring plans, I couldn't afford to wait for them to get down to the minimum thickness and decided to replace them now.

There's still some life left in these pads but they were retired early nevertheless

Removing the old pads

This was really easy. I put the bike into the maintenance stand and removed the front wheel. The pads are held in the caliper using a pin. The end of the pin needs to be straightened using pliers until it can be pulled out and then the pads can be pushed out with the end of the pliers.

The retaining pin is bent at one end, holding it in place

Having straightened the pin end, it was easy to withdraw

The old pads were pushed out using the end of my pliers

The pads emerging on the other side of the caliper

 Comparing the old and new pads

Old pads on the left, new on the right

As can be seen in the photo, the old and new pads are the same shape and size. They're both resin-based too so it looked like the new pads should be suitable for my system.

Fitting the new pads

Fitting the new pads was more or less the reverse of the removal process. To begin with, the new pads were mounted in the clip.

New pads in the clip

The pistons in the brake caliper need to be pushed back in as far as possible and I did this with a pen knife blade, pushing on both sides of the caliper so that I exerted an even force against the two pistons faces, one at a time.

Pushing one of the pistons in as far as possible

After this, it was a case of slotting the new pads in their clip up into the caliper and pushing the retaining pin through the holes to hold them in place. The end of the retaining pin was bent again using pliers. 

At this point I put the wheel back on the bike. A quick spin of the wheel revealed that the rotor (disk) was touching the pads. To remedy this, I loosened the caliper retaining bolts, squeezed the brake lever so the pistons pushed the pads against the rotor, straightening in the process. I then tightened the retaining bolts and that was it.

A couple of things did go wrong during this stage! First, it was really hard to undo the caliper bolts and in fact I broke my hex key in the process!

Note the broken tip of the hex key

Secondly, I stupidly squeezed the brake lever before I put the wheel back on and this caused a little hydraulic fluid to escape. No matter as the bleed process will remedy this.

Testing

I did a short test ride up and down the road and the brakes do work, no question. But they're not biting as hard as I might like and the front is making a horrible squealing noise. I cleaned rotors with alcohol-based disk cleaning fluid and this improved things but did not eliminate the noise.

Both the noise and the relatively poor braking are probably due to the need to bed the new pads in but I shall keep an eye on this.

Bleeding the System

On my last ride, I'd noticed that I was having to pull the front brake lever almost to the bars to brake. I researched and realised this was probably caused by air in the system and this is what bleeding is intended to remedy. Intending to learn how to do this myself, I looked into the process and items required only to find that the official kit from Shimano costs £30! For a single use plastic syringe, cup and some fluid?! That did seem rather poor value for money. And this was reinforced when I checked a local bike shop and found that they'd do the work for me for £25. 

So, I shall take my bike to the store and have a professional bleed the system. They can check my brake pads whilst they're at it.

And thus ends the saga of the new brake pads :-)