Brake fluid: Mineral Oil

Denis Shelston

Active Member
A picture that @america94 posted showed his new light, but it also showed the brake handle and its fluid reservoir. The label show Mineral Oil. Interesting.

Anyone has any insight on maintenance, how do you fill it up, probably using a dropper. Bleeding, probably.

Can good quality Olive Oil be substituted - nah, just kidding.;)

But this is a first for me. I've seen some videos on YouTube. Shimano has its mineral oil. So guess this is what need. Just rambling.

Here by myself, my better half is gone shopping.


After washing the bike a couple of days ago, it went from super silent to making this constant weird zing-zing-zing fairly loud noise, mostly under motor power. A similar, but much fainter sound seemed to come from the front wheel as well. Bikes sounds can "telegraph" all over the place, but it was definitely coming from the rear wheel. I knew the rear disk brake was warped a bit, so I thought it was rubbing. I took out the calipers, the brake pads and cleaned everything, including sanding down the pads a bit (they had become glazed). Noticed one piston in the rear was not coming out anymore (managed to fix that as well). All this thanks to youtube! Looking over videos on the processes, I familiarized myself with bike hydraulic brakes as well. It works the same as a car, except for the master cylinder. No reason to bleed the brakes unless you know or suspect that air got in the sealed system. Works best with a bike bleed kit and some specific mineral oil for bike hydraulic brakes. Do not used DOT car liquid as some suggest. Best not to mix different types either. There is a bleed valve on the brake handle (to add oil and prevent air going in with a reservoir that you screw in) and one on the caliper to bleed from there.

I also learned how to fix a warped rotor - I was sure at first only a replacement could fix the issue. Again, super easy with no special tool required.

I conclude anyone can service the brakes on those bikes with youtube help if need be, including bleeding/changing the oil. The calipers and pads are super easy to work with.

Anyway, after doing all this (and checking all the wheels spokes as well which could create such noises), the bike noise had not improved a bit. I thought then that it must be the motor, which was quite disappointing.

But then I remembered something: when I washed the bike at first, I moved the orange wheel reflectors to a different position to try to prevent them flying off like others experienced. Out on a whim, I put them back the way they were and went again for a test drive. Low and behold, the noise was gone... I spent 2.5 hours working on the brakes when it was the reflectors all along, but learned how to service the brakes and rotors from A to Z in the process. Quite satisfying all in all. I still can't figure out how the placement of the deflectors caused such a loud weird noise (they weren't rubbing anywhere), but it also explains why I was hearing some weird sound from the front wheel as well.

Lesson learned gentlemen, lesson learned!
Thanks for sharing this and for being our "beta tester" on so many products and issues!


Another thing that I remember now is that old Hank didn't like the spoke reflectors. As I recall they were usually an add on accessory. He felt that they put the wheels out of balance and that the centrifugal force from wheel rotation could push them out possibly bending the spokes. May not be as much of an issue with the heavy fat tire, wheels and rims but could have been with the thin alloy clincher and sew up rims that we sold. The old reflectors actually had a couple of twist turn fasteners that clamped them to the spokes; the ones that I see these days friction fit so much less secure as well. Progress:(


Yeah, I will replace them with something else. A friend of mine went to a bike shop when his orange one flew out and they recommended straw like reflectors that attach to the spokes. Effective, light, cannot affect wheel balance and won't fly off. With the black bike (and often dressed in black and grey myself), I am not very visible sideways at night... if I take out the orange ones without replacing them, that is asking for trouble (plus it's illegal).
We used to have reflectors that we could stick onto the front forks and the seat stays on the back. There are likely lots of options for self-adhesive reflective tape these days. The other option back then was a light that strapped to your leg; itwould move with the rotation of the pedals. Likely lots of tiny LED flashers it would work these days


although good quality white reflective tape works awesome, I did not want to put white tape all over a black bike. Took a chance on some inexpensive black reflective stickers off eBay BC, but might as well have put on electrical black tape. Can't even take them off as they are stuck til the end of time
A friend of mine uses a heat gun to remove tape. The key is to take your time and be gentle so as to not rip the paint. As the glue on the tape heats up, it loses adhesion and releases from the paint and metal. This is probably a good place to research online to get rid of the black not so reflective tape.