Here's the deal. Been having some brake issues, and damned if I know what the issue is.

Front brake got soft at a track day last fall. Bled them, still seemed soft. In fact, they were so soft, I ended up in a ditch on a test ride.

I figured I must have bled them improperly, so took them to a shop, had new pads thrown on, new brake lines, and bled them again.
Even after this, they were still soft, and now the rotors were dragging. The pulsating under low speed made me think it was warped rotors.

Replaced the rotors about a week or after that, riding the bike in the interim, but there was still crazy drag on the front. Plus there's a shuddering under low-speed braking, and once had the lever go to the bar with no resistance and coasted through a red light. Noticed that the fluid level had dropped a bit.

Took it to a different shop, and they pulled the calipers off, and found that not only were my pads worn completely down, one of them had in fact fallen out somehow, and the piston had been contacting the rotors. They seem to think that a set of new pads will fix it. I'm not so sure about that.

My thought is that there has to be a leak somewhere in the calipers, and that they need to be rebuilt. Any experts got some input?

The loss of fluid could be directly related to the loss of the pad as the space taken up would be filled by brake fluid space in the slave cylinders. I believe that the new shop has probably made a reasonable assessment and I would trust their judgement until they prove to be as incompetant as the last shop. You cannot evaluate the previous situation until all things are back to "normal"

True, true.
I could see the pads getting worn out in less than three weeks because of the drag ... but why is there any drag at all with the new rotors? And pads, which, at that point, were worn down and one missing? My brake lever is adjusted to the max, as I prefer a very short throw for braking. But throughout this process, the lever has come right back to the bar.

As for the shop, I am not patronizing them any more. I have a two-strike rule, and they've used both. Funnily enough, it was for the brakes on my other bike, too. They neglected to torque down the calipers. Free-floating rotors are great. Free-floating calipers, not so much.

most times this situation is due to air in the caliper(s). Normally, regardless of how or with what you bleed the system with. the air or old brake fluid in the caliper (i.e., piston chambers) is not flushed or purged. Brake fluid does not flow through the caliper and will always take the path of least resistance. When you pump the brake lever for instance and build pressure, then open the bleeder at the caliper the fluid gets pushed out the bleeder nipple without anything coming from the caliper. It goes right from the line/hose directly to the bleed nipple, the path of least resistance. Simply put if you left the bleed nipple open you will never get the caliper pistons to move in the slightest.

What I always do after getting the master cylinder and brake line/hose bled is to remove the caliper and brake pads and slowly pump the piston or pistons out as far as I think they will go before they pass the seals, and on the last pump of the lever hold it, open the bleed nipple and continue to hold the lever, then push the caliper piston farthest away from the bleed nipple in first until it bottoms in the caliper bore, then I push the second piston in that is closest to the bleed nipple (assuming it's a two piston caliper), then close the bleed nipple and release the brake lever. You may have to do this several times but what you are doing is purging all of the old brake fluid out of the caliper along with any air that may be still trapped in them. When you hold the brake lever in or foot pedal down this keeps the brake fluid from back flowing up the line and forces it to go out the bleed nipple.

On four (4) piston calipers, use the same procedure just always start at the farthest away piston from the bleeder and work toward it and always keep the master cylinder lever in and pedal down to close off the brake line to prevent back flow.

If you don't bleed the calipers and get the old fluid and air out the air will expand as it is the closest to the heat/friction at the pads and the air expanding will get the pads to drag, wear and make the brake lever feel like mush.

The first time you bleed the caliper you'll be amazed at how much air comes out of the caliper and in some cases how much dirtier and contaminated the brake fluid is in the caliper. Just remember the basics of the caliper brake fluid; it doesn't flow through or circulate through it.

SD#1