CaptainHaddock

Hey gang, I'm in the process of planning my upgrade to hydro-Di2, and was thinking about the advantages of running cx style aux. brake leavers on the bar top. I see that Shimano has their GRX BL RX812 units and wanted to see if anyone was running those or some other producers version therein, and challenges they may have had in integrating them into the system.

thanks!

bikeinxs

Have you ever ridden with the auxiliary brakes? I tried them a few years ago when they were first "in style". It seemed like a good idea but I didn't keep them on for long. If you are doing any real braking you are inevitably shifting gears as well which is the whole point of combining the two functions in one lever. The hydraulic brakes are so powerful that I find it very easy to effectively feather the brakes with my hands on the hoods. I didn't think the extra levers were worth the hassle.

fietsbob

https://bike.shimano.com/en-EU/produ...L-RX812-L.html

never heard of them until now .. go for it ! why seek handholding?


I have a cantilever braked cyclocross style bike with the brake cable housing interrupter levers,, that is a clever piece..

put a lever for a 3rd brake in the stoker's control?




..

CaptainHaddock

It's no so much that I need hand-holding, rather, wanting to know if anyone has used them, and if they have found them of value. I'm on my way up from mechanical to hydro on the tandem (I've been using hydro on my long-tail & half bike for years now), and am exploring all the options.

Re: stoker control of it. My initial thought was "yikes!" but then I guess some teams do run the old drum brakes via stoker control, so i guess it could be done. Probably not my cup of tea however.

fietsbob

As usual find and read the manuals..

https://bike.shimano.com/en-EU/produ...L-RX812-L.html
1) https://si.shimano.com/pdfs/dm/DM-GADBR01-02-ENG.pdf

2) https://si.shimano.com/#/en/iDM/GADB...PORTANT_NOTICE

bikeinxs

What a scary thought. I can just see coming into a corner a bit hotter than the stoker likes and then crashing because the stoker locked down on the brake. Wouldn't have mattered with drum brakes because they were fairly ineffective but with a modern hydraulic brake the stoker could do some serious damage.

CaptainHaddock

huh, Shimano's stating that their hydro systems are not tandem compatible. Interesting. Well whatever, still doing it.

bikeinxs

Weird. My bike was built up for me by someone from Shimano Canada with a similar configuration to his own tandem. Lawyers need to justify their existence I guess.

There are an awful lot of tandems out there with Shimano disc brakes.

CaptainHaddock

oh, I think it's probably their way disclaiming any responsibility / protecting themselves. from https://si.shimano.com/pdfs/dm/DM-GADBR01-02-ENG.pdf, if you search tandem you'll see this

"SHIMANO disc brake systems are not compatible with tandem bicycles. Because tandem bicycles are heavier, the stress on the brake system increases during brake operation. If hydraulic disc brakes are used with tandem bicycles, the oil temperature will become too high and vapor locks or ruptures in the brake hoses may occur, causing the brakes to fail."

*edit* and to be clear, I'm on hydro for my half-bike and my surley big easy (e-longtail) and have no concerns about moving the tandem to hydro.

ahultin

We are running xtr di2 hydro on a 15 rt2 and have had no negative issues. While I have not been on the tandem with non family , pre covid-19 I road with stokers that resulted in team weights skirting the RT-2s weight limit.
but to the original question, we dont run interrupters

DangerousDanR

You might want to take Shimano's guidance seriously. The first set of brakes I put on our Ritchey Double Switchback were Hope's E4 "Enduro" mountain bike brakes. I suspect they are more powerful than any road bike brake. They are 4 piston brakes and they have a fairly large swept area. And I had 203 mm rotors. When I needed to make a panic stop on a 10% hill at a speed of 40+ MPH, there was smoke pouring off both rotors and the rear was very, very hot. To say that we had a brake fade issue is an understatement.

OK, blame me. What was I thinking? We were beat, the Scalloway Hotel was waiting with food and beer, the wind was blowing 50 MPH and it was in our favor, and the blind corner on the hill was a wide sweeper. Who would think there would be road construction around a blind corner and the flagger would not be visible on our side of the corner? So, 500 lbs of riders, tandem, and luggage overwhelmed the E4 brakes.

I contacted Hope and was told in no uncertain terms to put the V4 downhill brakes on the tandem. By the way, Thorn has a write-up about their brake setup and why they will only supply a tandem with the Hope V4 brakes. You might want to read it before fitting disc brakes to a tandem. I wish I had.

I now have V4 brakes and the vented rotor in the back with an IceTech in front. Trouble solved. If I ever have a hint of trouble in the future there will be a Wilwood Kart caliper in the back.

CaptainHaddock

We've been on a few rides since I posted this question (stupid covid has kept our hydro hose on order...) and so we're still on our cable actuated disk brakes. Anyway, these rides consist of descending down rough logging gravel roads in the PAC West and the point of my inquiry is, do they help? See when I'm coming down a 10 - 18% grade on these rough roads, I'm not in the hoods, I'm in the drops because that provides me with the best mechanical leverage to slow our rig down. My hope with these cross top levers is that I can be in the hoods, controlling my braking and my shifting (where as currently, i'm just trying to not lock up / drop us).

bikeinxs

You won't be anywhere near the hoods with the extra levers. In fact, your hands will be on the narrow part of the flat bar where you have the least control and no opportunity to shift.

CaptainHaddock

well, yes/no. as mentioned in my op, I'm moving to di2, so given that buttons are/or can be everywhere I want them to be, (left right and center [should I want it]) and things like sycroshift exist, that's not an issue per se...

conspiratemus1

Gee, I can do that with my dual-pivot short-reach caliper rim brakes. They must be pretty powerful, too.

fietsbob

Well, with a Tandem.. you will have some long hose to the back disc caliper.. you have to buy more hose and fresh fittings...

good luck getting it leak free..