New road bike with Shimano RS685 hydraulic disc shifters

The problem is intermittent but every so often when downshifting the mechanism doesn’t seem to engage and the shifter move way past the normal ‘click’ point without having any effect. Sometimes it does this three or four times then seems to re-engage. I can’t work out any obvious cause or an action before that causes it to happen every time.

Any suggestions on a fix or is this a warranty replacement?

Send it back.

This is likely your problem.
But given that its new, i’d be sending it back.

Yep – send it back.

My ancient Ultegra device has started doing this but I just put it down to wear&tear…..

That’s what I feared.

Disc brake STI shifter….. not an easy swap out.

New gear inner, new bar tape, fill and bleed brake. Bike not bought locally……

Now I’ve read what fifeandy posted I’m going to try and fix mine 8)

I can’t work out any obvious cause or an action before that causes it to happen every time.

Daft question: You’re not inadvertently moving the up shift lever, are you? (Bulky gloves, etc.) It doesn’t need to move much to stop the other lever engaging.

New gear inner, new bar tape, fill and bleed brake. Bike not bought locally……

I had a sram shifter break and my LBS sent it to sram, they replaced it free of charge and the LBS fitted it for a very low price (and gave me bar tape FoC). Take it to a Shimano dealer and work from there.

Daft question: You’re not inadvertently moving the up shift lever, are you? (Bulky gloves, etc.) It doesn’t need to move much to stop the other lever engaging.

don’t think so – if it just did it once that might explain it but when it goes it usually takes 3 or 4 presses for it to work again.

I am not sure if by downshift you mean changing down to a smaller gear, or dropping the mech down to a smaller sprocket.

If the latter, I find that if the brake levers are squeezed slightly, then the smaller shift lever can fail to engage (are you riding on the hoods and unconciously pressing the brake levers when changing?)

I think I’ve noticed a similar effect without pressing the brake levers, if I push the smaller shift lever in a slightly diagonal direction (inwards and towards me, rather than just inwards).

However, I usually realise what I have done when this has happened, and either take pressure off the brake levers or push the smaller shift lever just inwards, so it doesn’t take 3 or 4 attempts to properly engage.

It happens when moving to a smaller sprocket on the cassette so it’s pressing the small lever.

Not 100% on the cable routing with the newer hydraulics, but double check that the hood rubber is on straight and not catching or dragging on the cable (or the lever mechanism) I’ve had earlier STis do this, that gives similar symptoms.

Also, make sure the tape isn’t stuck to the cable, or jamming the gear cable channel.

[quietly walks into corner hanging head in shame]

Daft question: You’re not inadvertently moving the up shift lever, are you? (Bulky gloves, etc.) It doesn’t need to move much to stop the other lever engaging.

Posting here for future search reference.

Not daft question. Rode in thin summer gloves today and it didn’t happen once. Was riding in leather gloves before with a hand still suffering from the crash that resulted in the new bike. Was sure I wasn’t touching the upshift lever but I must have been.