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how easy to diy di2

skeff10skeff10 Posts: 93
edited January 2015 in Workshop
How easy? And how do I work out what wires etc I need?
pretty competent and normally do my own builds and fettling etc
Also, could I run a sram chainset without issues on a di2 build?

Posts

  • trailflowtrailflow Posts: 1,311
    edited January 2015
    Very easy. Attaching the mechs is no different to mechanical. You still need to align and set the limit screws like a normal derailleur. When you insert the Di2 wires you will hear a 'pop' to know its seated correctly. The wires can take a bit of time to feed through the frame. But not having to adjust any cable tension makes up for it.

    Is your frame Di2 compatible for internal routing ? does it have cut outs inside the bottom bracket ?

    The simplest and often cheapest option (unless you go second hand) is to buy the upgrade kit rather than sourcing it all separately. The wires that come with it should fit most frame sizes unless you have a massive frame you may need to buy a longer down tube wire.

    My Ultegra 6870 internal upgrade kit came with

    Shifters
    Front and rear drailleurs
    2 shifter cables - 350mm each
    1 down tube cable - 1000mm
    1 front derailleur cable - 300mm
    1 rear derailleur cable - 500mm
    1 battery cable - 450mm
    Junction A box (fits on the stem)
    Junction B box (fits inside the bottom bracket/frame)
    Internal Battery
    USB battery charger/PC interface
    Di2 plug tool
    Grommets

    if you go for External its mostly the same except the junction B box screws underneath your bottom bracket (if your frame has that option - or if not you will need to attach it with cable ties)

    The external battery mount fits to the bottle cage bolts and the battery fits underneath the bottle.

    and ,Yes a Sram chainset will work fine.
  • Bar ShakerBar Shaker Posts: 2,313
    I run SRAM Force with Di2. I think it is the best of both worlds.

    The DIY install is very easy.
    Boardman Elite SLR 9.2S
    Boardman FS Pro
  • rafletcherrafletcher Posts: 1,235
    Bar Shaker wrote:
    I run SRAM Force with Di2. I think it is the best of both worlds.

    The DIY install is very easy.

    Presumably only the chainset and brakes?
  • PokerfacePokerface Posts: 8,640
    rafletcher wrote:
    Bar Shaker wrote:
    I run SRAM Force with Di2. I think it is the best of both worlds.

    The DIY install is very easy.

    Presumably only the chainset and brakes?

    Brakes won't work correctly with Shimano levers. Different pull ratios.
  • trailflowtrailflow Posts: 1,311
    edited January 2015
    i am using DA9000 levers with Sram Red 22 calipers. The modulation and power is spot on. i dont feel any negative effects. Its not ideal to mix and match but its not disastrous either. For me, it has improved my braking. i felt the DA calipers had too much power and not enough modulation.

    i wouldnt say 'brakes won't work correctly'. i'd say different combo's work better than others.
  • PokerfacePokerface Posts: 8,640
    trailflow wrote:
    i am using DA9000 levers with Sram Red 22 calipers. The modulation and power is spot on. i dont feel any negative effects. Its not ideal to mix and match but its not disastrous either. For me, it has improved my braking. i felt the DA calipers had too much power and not enough modulation.

    i wouldnt say 'brakes won't work correctly'. i'd say different combo's work better than others.

    I stand by what I wrote. I didn't they it won't work. But it doesn't work correctly. As in the way it was designed to work.
  • Bar ShakerBar Shaker Posts: 2,313
    I'm using Ultegra callipers.
    Boardman Elite SLR 9.2S
    Boardman FS Pro
  • I have upgraded a couple of bikes to DuraAce 9070 internal Di2 and its quite easy assuming you have all the correct cover plates for any un needed holes and custom gromets for your frame type.

    The hardest things is to get a hang of is how the wires route within your frame as they may be different to how the existing cables route.

    I did the following to make threading the cables easier:
    Threaded a length of brake cable through the frame. This is quite stiff and yet flexible so will bend as required within the frame.
    I then tied some fishing line around the end of the cable and pulled that through the frame.
    Next I tied the Di2 wire to the fishing line and pulled that through the frame
    Connect the wires to the junction boxes and components

    The actual setup of the mech's which is a doddle if you follow the DI2 dealer manual instructions.
  • 964cup964cup Posts: 1,359
    Pokerface wrote:
    Brakes won't work correctly with Shimano levers. Different pull ratios.

    I'm using SRAM Red Aero brakes with DA9070 TT levers, and they work very nicely. Which combination gave you a problem?
  • PokerfacePokerface Posts: 8,640
    964cup wrote:
    Pokerface wrote:
    Brakes won't work correctly with Shimano levers. Different pull ratios.

    I'm using SRAM Red Aero brakes with DA9070 TT levers, and they work very nicely. Which combination gave you a problem?


    I'm not sure the TT levers work the same way as the road brakes. (Plus most TT braking is poor at best so it's hard to distinguish between good braking and poor braking!)

    It's a fairly well documented that Sram and Shimano road levers pull different amounts of cable to the brake. This results in either braking that is too hard or too soft, depending on which way you mismatch the items.

    Again - I'm not saying that you can't make it work. You can. But it won't work the way it was designed and your braking will be compromised over using the correctly matching callipers.
  • PokerfacePokerface Posts: 8,640
    Here's a great answer I took off another for from the guys at Fairwheel Bikes. They know a few things!



    "I'm not an engineer, nor do I play one on T.V. but I will try to pass it on as I understand it(in my own convoluted way)

    With brakes there are several things to take into account. First as leverage increases cable pull decreases. This is why brakes with alot of mechanical advantage such as ZG tend to not have much range in their arms movements.

    Some brakes have linear rates while others are progressive.

    Rim width also matters when it comes to brake function.

    Levers and brakes are designed with a ratio that puts the whole system into a functional range. Too much mechanical advantage in the system and the pads don't move far enough to clear the rim. Too much travel and the system lacks stopping power. There are lots of results you can get from mixing systems, especially when you add in the variations of more progressive brakes.

    In moving the cables to be internally routed on the 7900 levers they ended up in a position where they needed to have more cable pull to make them function correctly(a range which Shimano thinks is ideal). To offset that they increased the mechanical advantage in the brake. The combination produces a brake with a total system value equivalent to what 7800 had been.

    Using old levers with new brakes will not pull enough cable. It causes the caliper to move at a quick rate which reduces it's mechanical advantage and gives a feeling of on/off with very little in between, even though it actually lowers stopping power. Mix them the other way and have a feeling of too much range. This produces lots of stopping power, but only late in the stroke when the lever is coming close to hitting the bar.

    Then take into account that some brakes start off with a 1:1 ratio but then ramp to a 1.25:1 or 1.5:1 ratio to increase stopping power.

    So keep in mind what components you have in the system. A lever that pulls lots of cable needs a brake with a higher mechanical advantage. A brake with lower mechanical advantage needs a lever with higher mechanical advantage(which pulls less cable). A wider rim will need a brake that has more movement or less mechanical advantage. Think of it as a teeter-totter(see-saw to some). A 200lbs and 100lbs person can offset each other, but the 200lbs person has to sit half as far from the center. So the 200lbs person will move only half the distance relative to the 100lbs person.

    I'm not sure if any of this makes sense.

    Basically the short answer is yes, almost anything can be made to work with any other system. However, it's not going to work in a way that it's designers would consider most efficient.

    In the end it comes down to riders. Some guys are fine using just about anything and others require exacting tolerances in the feel and function of the their bike. I think it will matter more what kind of rider you are than what combination you use.

    I know a couple manufacturers feel the new lever does not produce optimal results with current brakes and are redesigning the brakes to match. For some it's a function of stopping power, for others it's about gaining more adjustment range, but most feel it's not ideal."
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