OH FAQ!

Why change brake fluid ?

1. The aesthetics Your life may depend on it

2. The physics, Generally speaking we have 2 types of brake fluid. DOT3-4 and DOT 5.1 these are polyglycol based and are hygroscopic, they absorb water somewhat aggressively too.
In years passed a former employee of mine found out how much they absorb water by sucking brake fluid from a caliper and spitting out the fluid until he was happy with his efforts, some 5 minutes and 3 mouthfuls of fluid later. He washed out his mouth and found bits of skin being washed out, the bits became bigger which distressed him somewhat, he was falling apart from the inside outward. After a while his prematurely decaying body ceased to decay and he asked why he now had a sore mouth. Quite simply the brake fluid had removed the moisture from the first layer of skin in his mouth rendering it dead and useless, It then peeled away in lumps. DO NOT TRY THIS AT HOME ! When brake fluid i.e. DOT 3, 4 or 5.1 is exposed to the atmosphere it absorbs water; this lowers the fluid boiling point which can have dire consequences. The other problem is when fluid is absorbing water it also forms a gooey crud that can block master cylinder return parts, causing rusting and seizure of pistons; costly items to repair and put right. DOT5/ Dot 5 silicone high boiling point, non hygroscopic, kind to paint work....but But-big BUT. Shake it up and it holds air bubbles (very small bubbles but they are there) and it takes days to get rid of them, also being silicone based, it's not a good lubricant and doesn't help piston return in your master cylinder. Bottom-line...Most machines come with DOT 4 brake fluid in brake systems, it is not a “sealed set it and forget it system”, it needs maintenance, changing brake fluid is a good idea. I change mine every year.

Why do my brakes drag when cold ?

Usually it's because the callipers require overhauling, i.e. strip, clean, rebuild with new seals. Most road bikes have two seals per piston in a calliper, the main fluid seal and a dust seal. What happens is that moisture gets between the seal and calliper body which is usually aluminium and we have all seen oxidized aluminium, (white furry aluminium) this oxidization is in a tight space and it grows, this putting pressure on seals and pistons, and causes sticking brakes. Older machines tend to suffer more brake problems because of age, lack of effective maintenance and of course the weather doesn't help.

Why does my brake fluid go black in the reservoir even

when fluid has been changed ?

Simple answer - Brake hose degradation or your rubber brake hoses are f***ed (have seen better days) ALL manufacturers recommend brake hose replacement in their service itinerary, what changes and when. Putting braided hoses on stops this problem, because the fluid runs in a Teflon tube surrounded by stainless braiding, these are widely available and also improve brake performance.

Should I upgrade my brake pads when they are due for

changing ?

You can upgrade if you feel you're riding needs it. As with most upgrades there is a cost difference and it's not in your favour. Going from organic to sintered brake pads will improve braking performance. I would only upgrade front brake pads and not rear, unless you have a bike with linked brakes like Honda produce, then brake pads must be identical and all replace at the same time.