TLoubet

I have a new 2018 Synapse with SRAM Red ETap. The rear hydraulic brake functions, but the lever pulls all the way back to the bar. If I pump it several times, it gets better, but not all the way normal. The lever for the front brake is totally normal.
The shop bled it twice, and it got a little better, but after a week it's back to where it was. Unfortunately, they are several-hundred miles from me.
The obvious answer is an air leak, but wouldn't the fluid leak then as well? Where could it be leaking that wouldn't be completely obvious while they were bleeding it?
Any thoughts would be a big help. Thanks.

TLoubet

Is it possible that the master cylinder itself is faulty, and it's letting fluid past the piston? That is, it seems like it's leaking, but there's no fluid visible, so maybe it's leaking WITHIN the system?
Anyone else experience this?

Andrew R Stewart 

Leaks are not always easily noted when bleeding, usually not in our experience. No surprise at the SRAM's having this problem, we've found them to be more problematic in general compared to Shimano. But to SRAM's credit they are pretty responsive to warranty claims. Has the shop called SRAM for this possibility yet? I don't know of a warranty that's mileage dependent so how many you ride between incidents shouldn't be the issue, the time between is what is usually considered. Andy

TLoubet

Andy-
thanks so much for the note. Yes, we called SRAM and they were pretty baffled. Best guess they have is kinked hydrolic lines or leaking fittings. We will pull them apart completely and see, but I wondered if anyone else had a similar experience.

AnkleWork

Maybe an internal "leak" past the cup seal allowing pressurized fluid back into the reservoir -- a common malady of all types of master cylinders. SRAM has seen it before.

TLoubet

Great. Will check that. Thanks.