Xavier65

Tektro (and presumably others) do an auxiliary brake lever for mounting on the tops of drop handlebars in addition to normal, primary brakes already fitted, e.g. the RL570. These effectively pull the brake cable by extending the cable sleeving.

Has anyone come across auxiliary brake levers that work with hydraulic brakes?

These would be ideal in combination with finger tip, trigger gear shifters (mounted next to the auxiliary brake levers), for someone crossing over from road/racing into touring/audax/bikepacking.

Xavier65

Ooops.. "Here, let me Google that for you"

https://www.bikeforums.net/tandem-cy...ake-lever.html

Sorry. :-}

Xavier65

The next question is therefore, is there a hydraulic brake lever (drop bar) that is compatible with the Shimano GRX BL RX812, that ISN'T DUAL CONTROL?

Xavier65

There is the TRP Hylex hydraulic brake for drop handlebars (brake only), but it's not clear if this is compatible with the Shimano GRX BL RX812.

veganbikes

It could likely work you just need the correct fittings to make it work. We actually had some hydraulic sub levers working with SRAM levers and those are two vastly different fluids. I cannot speak to total longevity but it did work initially and on various test rides just fine.

You will likely want TRP fittings at the main lever and the caliper and then Shimano fittings at the sub levers in and out.

Polaris OBark

I have TRP Hylex mated to Shimano calipers, so my guess is it will work. (TRP and Shimano have different olives and barbs, so you need to deal with that.)

Xavier65

I can't believe the fluids can really have such a significant difference that one jeopardises the integrity of components designed for the other. Ok 'YMMV'.

As long as it's just fittings, and not so incompatible that one uses imperial diameter pipes and the other uses metric, say.

So, this sounds like a goer: TRP drop brakes + TRP calipers + Shimano.sub levers. And 22mm dia Shimano trigger shifters next to the sub levers.

Just have to put 22->24mm and 25.4mm to 32mm shims in various places on the 22mm drop handlebars, e.g. https://amzn.eu/d/992iAjE

Polaris OBark

SRAM uses DOT fluid, and it will destroy Shimano or TRP parts. (The other way around it probably fails less dramatically. Mineral oil is fairly inert.)

Polaris OBark

Why not just use GRX levers and calipers?

veganbikes

DOT and mineral oil are quite different in composition.

Your idea sounds horrible just get a flat bar bike or use proper STI levers or some similar integrated lever. There is no situation where I want drop bars and on my hoods I cannot shift and have to move to the tops to shift and then move back. If I did want shifting there I would go Di2 and that way I can run satellite shifters so I have shifting from my main levers and then anywhere else I might want it.

I would stick with a bar like the Surly Moloko, Koga Denham or Veto Orange Crazy Bar and then I can run whatever brakes I want with no sub levers needed, have a place to put my hands that is similar to where I would be on the hoods and run trigger shifters.

Xavier65

Has anyone actually experienced DOT fluid destroying Shimano/TRP parts?

Not being skeptical, just wondering.

Polaris OBark

Feel free to try.

Xavier65

Well, as someone who has ridden mostly on the tops, with auxiliary levers and fingertip trigger shifters, for many years, but has enjoyed the ability to move down to the drops when descending >50Km/h, for which brakes (but not shifters) are necessary, I am evidently in a peculiar class of tourer.

I also have a road bike with brifters on drops, and no way would I want to tour on that bike. So, it's not like I'm unaware of the 'pleasures' of brifters.

I will check out the bars you mention, but I'm wondering if the setup I'm pursuing is simply offensive to you.

Xavier65

I guess there's a long running thread on this subject (like crash helmets), but as far I can make out there should be no problem using DOT4 or mineral oil in any braking system, as long as the same fluid is used from day 1, i.e. if it's factory installed with mineral oil, you can't drain it, and use DOT4 - or vice versa.

So, if Shimano's sub levers were intended for DOT4, and TRP's levers and calipers were intended for mineral oil, there would be no problem (at install point) using mineral oil throughout.

veganbikes

It is just a silly set up. I am not offended, people do whacky things. You sound like a good candidate for Di2 though.

Xavier65

I've checked out the bars you mention, but they don't offer the upright, comfort touring posture, with brakes+shifters, for the majority of the riding, and an option for a streamlined tuck position with hands on drop bars, with brake levers at the ready - for the occasional high speed descent.

I've checked out the Di2 stuff. It is weird that manufacturers are only just discovering the possibility of drops being used in the manner above - as opposed to 90% on the drops, and on the tops/hoods only for the rare cruise - or possibly when ascending (when brakes aren't so important, but a tweak to the gearing is).

Here's another option for those needing a 22mm bar for top brakes/shifters, with 24mm drops for brakes only: https://amzn.eu/d/eSclkIN

Polaris OBark

Shimano and TRP use the same mineral oil.

mtbikerjohn 

If I recall correctly, the seals and o-rings used in a Dot 4 brakes are different materials than those used in a mineral spirit brake..The mineral spirits seals would literally dissolve in DOT fluid, and turn into a gummy mess..

niknak

I agree with VeganBikes. Move to alt bars since you say the majority of your riding is in the upright cruising position. Tons of braking and shifting options to suit your preferences. And give up the tuck position for the occasional high speed descent. You can still tuck on alt bars, just not as well as drop bars.

This might be a left field option, but you could consider using some alt bars combined with a dropper post to get more aero on the descents.

If you don't want to give up drop bars, then it looks like GRX is the solution.

Otherwise, you'll just end up going down some weird hodge podge rabbit hole setup that's going to cost more time and money than it's worth. But hey, if you enjoy experimenting none of us are going to stop you.

tcs

The TRP HY-RD are cable from the lever to the brake body, where the hydraulic elements reside. Regular ol' cable aux lever = straightforward.

Tourist in MSN

If everything works as you predict, let us know in a year.

If it does not last a year, let us know that sooner.

Xavier65

Is there such a thing as a hydraulic brake hose union or tee piece?

This would either be a simple connector of two brake lever hoses to a hose leading to one disc brake, or it would also have two valves such that if either brake failed or was removed, no fluid would escape, and the remaining lever could continue to operate the brake.

tombc

Please provide a sketch of how this might work.

If you had to have all that stuff yeah I'd go Hy/Lex with the GRX interrupters in a second. Would never tell a customer to do this but I'd try it myself. I am not sure of the best way to get rapid-fire shifters on road drop bars though, you might have to go with a "lesser" shifter like a thumbie on a mount that size, or something. There are some lesser band-on paddle type shifters in like 3x7 that would work, they come on department store road bikes sometimes.

Xavier65

You can get 22mm diameter drop bars (instead of the normal 24mm).

The GRX secondary brakes have to go on the wide bit near the centre (or on big shims further away).

I then thought, "Hey, we're dealing with fluid here, not cables, so a T-piece should be a doddle", and so normal flat bar brake levers should work fine as secondaries.

So, although there is a solution already, I think an even superior one could be found if there is such a thing as a hydraulic brake pipe T piece.

Xavier65

Here's a sign that this part already exists: https://hollandbikeshop.com/en-gb/bi...-black-735326/

A Tektro t-piece.

I think this is designed to enable one lever to operate two disc brakes simultaneously (tricycle?), but unless it has internal valves, I would have thought it can also be used to enable either of two levers operate a single disc brake.

There's also a Magura t-piece: https://www.bike-components.de/en/Ma...-Lines-p60538/