Spot whats odd with this ' and i don't mean the lack of bar tape'

[motorapido]

Been working on this for a couple of weeks and finally got a couple of set of them built up. One set about to be shipped out to Kowloon.





Possibly the direction Sram will push next with Etap following the UCI ruling on Discs for the road. but anyways here's my take on it.

[Synnove]

Wait... are you trying to get the hydraulic brake levers to work with regular rim calipers?

[motorapido]

Haah Haah, Have a closer look, its Di2 levers modded to operate the lever body mechanism for Sram HydroR rim brake calipers

[Synnove]

Ahh that makes a bit more sense ; ). Honestly, I didn't know SRAM was producing hydraulic rim calipers; I was only aware of the Magura calipers. Is the modulation pretty similar compared to the SRAM levers?

[motorapido]

Modulation is spot on and identical to the Sram units, my modified levers run identical angles and pivot positions to the original Sram levers,

Complete brake/shifter weights before i shortened the hoses to suit my frame were 390grams for the rear and 380grams for the front,

Have got a set of the Magura's gathering dust in the garage, there fugly and a pain to bleed and set-up, either loads of power and no rim clearance, or enough clearance but mushy at the lever. the pad to rim setup is achieved by spacer washers on the pad bolts which is a bit rubbish compared to the Sram setup, which works just like a cable adjuster, with an additional cam lever to open up the calliper space for wheel changes.
Never really got the Magura's to work well with 6770 Di2 levers, but it may be the cable pull ratio wasn't right with that setup.

[grilledcheese]

very cool mod. I hope sram does some sort of wireless 1x shifters with hydro discs for cross. I would be drooling

[Nefarious86]

Have you thought about using R785 levers with Sram callipers? Or are the ratios of the Master/slave too far out?

[motorapido]

Haven't tried them, but the biggest problem would be seal compatibility with the fluid used, Sram use DOT 5.1 brake fluid, Whereas Shimano use a mineral oil. Use the wrong fluid and either the lever or calliper seals will be destroyed as they aren't suitable, they either swell or go like gum.

I do a lot at work with various seal material and rubbers, and chemical attack of the material compounds can be a big issue.

[mattr]

Would it be possible to strip down the SRAM caliper and replace the seals with mineral oil compatible ones?
(I believe SRAM use slightly more standard seals than shimanos proprietary stuff)

[breezerboy]

Would silicone based brake fluid work?

[Nefarious86]

Scrap my idea. Completely forgot the most obvious hurdle haha. This is a pretty awesome project all the same

[motorapido]

Possible with the Silicone fluid or Seal changes, as long they are fairly standard O rings or Quad ring seals, the problem is often getting them in the size and material grade both in base material and hardness, thats suitable.

Whereas the lever mod is surprisingly simple to do, and you could convert back to the Sram mechanical shifters if you wanted to sell them on later, The only mods to the Sram bits is a small groove in the lever body to route the Di2 cable out next to the hydro line, and tapping a thread in the end of the lever pivot pin.

The hacked part is the Di2 lever which is written off, however Shimano do make it as a spare also. Its the pivot block that took the time to model and perfect.



i have a few sets of spares if anyone is interested.

[mythical]

I really appreciate even the idea of coming up with this solution, let alone the execution of it. So brilliantly simply yet so effective...

[XCProMD]

Best post in ages. Congratulations


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[mattyNor]

So I've always known that SRAM hydro stuff can't take mineral oil and vise versa, but I've never understood why. Dot fluid I know is corrosive so I understand why you can only use it in specific systems, but mineral oil is inert so what causes the issues since I don't see how it would interact with rubber which is also pretty inert?

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