uspspro

Well, there is this contraption from a company in Switzerland:




BUT... I was thinking I could do the same thing for cheaper / less exotic / etc...

I could just modify an Avid Juicy lever and use an Avid Juicy caliper in the rear.

Here's my idea (This would be cake to fabricate). I might go about the mounting/configuration differently once I had the parts in hand:





The idea is basically to pull the lever from really close to the fulcrum, so that the road levers would have enough pull. The excess lever would be sliced off. The ideal point at which the lever would be pulled from would calculated, of course.

What do you guys think?


EDIT: When I said stoker peg... I mean on the captain's bars, of course.


This is not a good idea... see below.

There is obviously a reason this hasn't gone mainstream, and is only made by a small Swiss company

TandemGeek

I think you should stop screwing around with something as important as your brake system and put the stock Avid BB7 caliper / rotor / pads on... and then carry a spare set of pads.

uspspro

Hmmmm... I really don't think that a brain storming thread constitutes any dangerous activities on my part. I am not planning to go do this, I was just posing a hypothetical for feedback.

The internet, doesn't convey tone very well.... but I feel somewhat offended.

I take the safety of my wife and my own safety very seriously.

As for what I was actually running.

-stock avid caliper
-ebc gold pads for the avid BB7 (recommended by Precision tandems... hey they know what they are doing right)
-BPB, also recommended by several tandem teams/mechanics I know.
-Hope 203mm rotor (proper size for the caliper/bracket), has been used by a team here on BF with good success.
- Campy cables (hey... you are using them... right)

I chose the components to IMPROVE the braking, and to improve the safety/performance to our bike, not to "screw around." Now obviously, the system is not working too well, but neither are the Avid setups of several teams.

I don't see how I was "screwing around" with my actual setup....

The paint drawing... yes... I was screwing around... but that's not what is on our bike.


I have swapped the pads to the Avid pads, and have switched the housing to compressionless. The lever feel is improved. I need to brake in the pads again... but so far, I can lock up the rear with just me on the bike. We will do a break-in ride shortly.

uspspro

OK... getting back to the brainstorming...

From an engineering perspective this setup would have several advantages.

1) pistons on either side of the rotor = smoother, more even pressure, and less warping of the rotor
2) No long brake cables, prone to making the brake lever feel like mush, and making it difficult to setup disc brakes.
3) Hydraulics offer more power than cable pulled mechanisms (with the size levers we are talking about on bike disc brake calipers).

uspspro

Actually, Tandem Geek, you did provide me with some very useful insight...
Just not in this thread, but here: https://www.bikeforums.net/showpost.p...23&postcount=5

That was an excellent post.

I can see how with a hydraulic system, having a cable anywhere in it would not be a good thing.

Hence the downfall of Santana's hybrid setup.

The cable eliminates, from the lever, the direct feedback of the hydraulic system. All cars and mountain bikes have a direct push rod from the lever to the master cylinder. Since the fluid expands, this direct connection should be present.

Also, as mentioned by TandemGeek, the Santana setup was a closed system, which is no good either when dealing with fluid expansion.

uspspro

This... https://www.canyon.com/_en/technology/project68.html

However is pretty cool. Looks like they designed their own levers.

uspspro

Well, this thing is actually still available: https://www.velo-direct.ch/details.php?code=FE-058.501

I don't want it, since I finally got the Avid working well, I will update my other thread about that!

However, just thought I would share this info... Here is a pic from the link above;

Ashen

I'm speaking from some level of ignorance here, since we bought our tandem used, but bear with me. It is a slightly older Rodriguez, that instead of cantilever brakes the previous owner had installed Magura hydraulic rim brakes. Is there some reason that these drop bar hydraulic levers couldn't be attached into the hose of a Magura disc brake?

uspspro

I think it would depend on if the master cylinder size is the proper size for the cylinders in the brake caliper.

It's funny in the automotive scene, you have people put huge multi-piston brake "upgrades" on cars, and use the stock master cylinder. You can end up with a pretty mushy pedal.

Also, you would obviously need bar-end or downtube shifters to use those levers.

Ashen

Thanks, I didn't consider the shifter implications, since I mostly use bar end shifters anyway. I suppose being able to use hydraulic brakes with brifters was the true goal here.

Ritterview

................................................................................ Bummer of a birthmark, Hal