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[bigalfromwigan]

Hello all,

I am now riding my second Bullet and very pleased with it too.

There is one thing i have noticed with the new one that the old one didn't have and that is that when I use the front brake, I can feel what I call pulsing on the lever. Is this because the disc is not floating?

When examining the disc, I am not 100% convinced it is running true but I could be wrong. I would need to set up a proper jig to check it more accurately.

While I was looking at it, I noticed that stamped into it was the tolerance so I measured it and it is within 0.2mm of the tolerance so what kind of life would possibly be left on it? I know, it depends on how I ride and how often etc. I'm just looking for a ballpark figure on that and I won't sue anybody if I get different results.

So looking forward, what is the collected opinion of the brake discs on ebay compared to the ones that our hosts supply? Obviously I would like to save money but if it turns out the £40 ebay ones are made of cheese then it's false economy of course.

[stinkwheel]

Obviously the measurement you want is the runout which would need to be measured with a dial guage indicator.

However, as you have noticed, it's pretty near the wear limit anyway so might be worth replacing anyway.

The disc on your bike doesn't float but the calliper does, it's free to move on two pins.

There can be other causes of pulsing too but excessive runout on the disc is the most common. In my experience, it's not always a warped rotor. A more common cause is corrosion build-up between the rotor and the hub so removing the disc and cleaning up the mounting can solve the problem.. I have also seen quite a few (new) discs over recent years which were not of a uniform thickness, since you appear to have a micrometer, this is another thing it is easy to check.

[Andy C]

You don't say what model your Bullet is.

FWIW I have a disk brake conversion (from our hosts) fitted to my 612 - never had any pulsing issues with it, and I find it more than adequate.

If it is pulsing as you say that sounds like it is warped, I would only ever buy a replacement form a reputable source, afteral your life could depend on it.

Just my 2 penneth.

[bigalfromwigan]

Thank you for the replies. Of course I forgot the basics - I'll have a look at the pins the caliper is mounted on to see if it is indeed "floating" or not. That should correct any issues. In the interest of economy I will wait until I have used up the last 0.2mm of wear before I stump up for a new disc though. By then the pads might need replacing as well, and it goes against my Yorkshire roots to replace something that isn't totally worn out.

Thanks again.

[Leon Novello]

Probably as the others have said. This is also noticeable in cars when the discs have been machined too often, making them very thin, they tend to get hot more quickly and warp, resulting in the pulsing being felt at the steering wheel.