Let's start this post with a warning, this may be a long post. If you are just looking for some pictures and a summary, check out our blog at http://fairwheelbikes.com/cycling-blog/
We've often been asked about these projects and how they come together so we're going to try and chronicle that a bit. While we aren't able to cover everything that happened we will try to be fairly inclusive.
The project started last year on the 2nd day of Interbike. We discussed most of the ideas and continued to do so for several months. We worked with several companies to line up what we wanted to do with this project and that came with lots of ups and downs. We had several people back out as we came closer to building. Jump forward several months and we have an outline of what we want to do.
At that point we gave the idea to forum member jeffr (Jeff Roberson) and discussed the options. The idea we decided to move forward on was a Di2 mtb with a brain that would allow us to do linear shifting. Basically the rider would tell it to shift up or down and the group would figure out and shift either the front, rear or both derailleurs (side note, when I first came up with this idea I couldn't decide if I really liked it or not. I gave the idea to one of the top mtb pro's in the U.S. I won't mention his name since he's a Sram rider, but it does rhyme with odd bells. It was his response to the idea that made me decide it was worth pursuing, and at this point I'm really, really glad he convinced me so.) Jeff took the idea and ran with it adding a lot of features to it and a world of possibilities. We'll cover those at the end.
The first step was to send jeff a Di2 group that he could reverse engineer and see what we could do. Jeff can fill in as much about what he did as he wants to or does not want to reveal.
After figuring out how the stock system works, he set off to designing the new setup.
Then to testing and prototyping the board.
After testing with the prototypes Jeff had a production one fabricated and sent to us.
Meanwhile in the months while this was going on, the project was developing as a bike also. We had a color scheme but didn't know exactly how we wanted to build it so different options were set aside.
Some parts were pulled to tune the rear derailleur. The upper pulley needed to be changed from an 11t to a 10t. The weight on the rear derailleur dropped to 204.6grams.
Next some special rims and hubs arrived from Edge and Tune. This was the first part of the bike that started to come together. The wheelset with the Edge 29 tubular rims, Tune Cannonball and Dezible hubs and Pillar 1422 spokes ended up at sub-950 grams. More on the wheelset can be found here: http://fairwheelbikes.com/cycling-blog/ ... elset.html
To that wheelset we added a set of Scrub race day magnesium rotors (huge thanks to Scrub for getting these to us in time.)
Then a special lefty fork arrived from Cannondale and was fitted with a Project 321 steerer tube adapter so that it would fit our bike(again great big thanks to P321 for helping in such quick time with the steerer adapter). The finished weight of the cut fork was 1270.5grams.
Just after the fork a custom titanium Titus frame arrived. While not particularly light at 1426grams it wasn't really heavy for a ti frame and was a perfect fit for the project in our opinion. We felt that ti had the right feeling for a race worthy hardtail that we didn't want to be considered delicate. Unfortunately since the frame and group were being built at the same time we didn't have the luxury of designing the frame with the Di2 kit in hand and weren't able to do it fully internal as we didn't know exactly where we'd need entry/exit points or how large they'd need to be.
It was finally time to start building the bike and testing the brain in the real world.
Some Dugast tubulars were mounted to the wheels, and the fork, wheels and Di2 group were hung on the bike.
Then we tried several options for the build kit and finally settled on our parts.
Edge: stem and bar
Kcnc, cranks, ti pro lite post, sc11 seat collar, grips, x7 brakes, Morion M3 ceramic headset, bar end plugs, ti dlc knife pedals, valve extenders, skewers.
Tune, Kom vor saddle, new bottle cage.
That made for a complete bike that could be ridden and tested. We hooked up the brain hanging it in a plastic bag on the bar
and plugging the leads directly into the stock rear wire kit
I tested the bike in the stand and was totally excited with how well it was working. Finally it was time to take the bike for a test ride. I had high hopes but not high expectations. Here's the problem I was having. Front and rear derailleurs shift very differently, they feel different and typically allow/require different amounts of pressure on the pedals to make a clean shift. I figured that not knowing when the system was going to shift the front would be a problem. My guess was a front shift when I was not expecting it would seem very out of place compared to the rear only shifting which would precede it. To my absolute surprise this was not the case at all. The Di2 shifts the front so quickly and firmly that front shifts were hardly noticeable. This was really exciting. I now thought that we really had something special with this. I immediately sent an email to jeffr and let him know my results. Again, I have to thank him as he really has built something so very special.
Now it was time to move on to the details. Brake lever and shifter placement were next. The brake lever was slotted a bit more to allow a zip tie to pass through it to mount the shifter exactly where we wanted.
Then a couple of levers were used to combine parts to make a mixed color set that we thought looked best.
We had two custom batteries made for the project. Since our local hobby shop didn't know how quickly they could make a custom battery, the first was made by Coloclimber, thanks Nathan for your help with that. A nice added bonus was that the new batteries saved almost 30 grams of weight by loosing the casing and being installed inside the seatpost and the frame was wired for an internal battery.
Programming was done and finalized.
Finally it was time to install the brain into the customized Edge stem.
Finally the bulk of the bike was done:
some new decals were sent from Edge to match a little better with the bike
the last step was to install the bar end plugs and add the Titus and Fair Wheel decals to the frame and it was done.
So at this point I guess a lot of people may be thinking that it's neat but nothing more. That seems to be the consensus amongst those that have heard about it. However everyone who has gotten a chance to ride or shift the bike has left with a completely different feeling. Forum member movr was in the other day and didn't know anything about the bike. He was asking what was so special and how it worked with only one shifter. We told him to pedal it and start shifting and he'd notice. He went through all the gears and as the bike shifted in front and he kept going someone commented, "he missed it." At that point someone pointed out that he had just shifted 13 times in a linear sequence and that the front was shifting as well as the rear. movr hadn't even noticed. That was exactly what we were hoping for.
As I mentioned Jeff went way beyond my expectation. I had thought it would be a simple program that tells it to use certain combination's in order. I thought that if you were moving from smaller to bigger gears and hit the spot where the front shifted and then immediately shifted to a lower gear it would again shift the front, but it doesn't. It knows what ring you are in and opts to stay in that ring as long as it can without affecting chainline. So the combinations of front and rear that you might use in going to larger gears will not be the same when going to smaller gears. It doesn't eliminate the duplicate gears, it just chooses to ignore them at inappropriate times and use them when it's appropriate.
Here's an example.
If you are in the 29/16 and shift to a higher gear it moves just the rear and ends up in 29/14. One more shift to another higher gear and it shifts the front also so you end up in 42/18. Now from that 42/18 if you decide you want to back down to a smaller gear and downshift, it doesn't move back to the 29/14 that it just came from but instead chooses not to shift up front and stays in the 42 but goes to a 20 in the rear. You end up with the same size gear you were in previously but without having to shift the front. It will continue to do this until it decides that the chainline is not optimum and a front shift would be better than a bad chainline. It's really a very clever program.
While the sequential shifting is certainly my favorite aspect of it, it's not the only one. We kept things simple for interbike so as to not make it overwhelming. The other thing that is currently active on this bike is gear dumping. Holding one button will race through the gears without stopping at each one. You can dump not only to bigger gears but also to smaller gears. A full dump of 13 gears can be done in just about 1 second. Jeff tells me that he intentionally slowed this down with some built in delays as the derailleur could move much faster than this but there we didn't know what would happen if it went shifting both front and rear simultaneously and at full speed.
Multiple modes are one of the things that make this group exciting to me. If the sequential shifting isn't your cup of tea and you prefer to shift front and rear independently and into the position of your choosing you just simply use manual mode. In manual mode the shifter buttons individually control just the rear derailleur moving it either up or down when you tell it. To shift the front you can just push both buttons together and the front will shift. Since it's a double it doesn't need to be told to shift the front up or down, but only to shift it to the other position.
As I continue to ask jeff if different things are possible I have yet to find a scenario that he can't make work with some programming. His reply so far has been, "if you can think of it, we can make it work." If we added a 3rd button into the mix it would really open up more possibilities.
For me options are countless, a usb plug so that it can easily be plugged into a computer and new "apps" downloaded and installed. Mix it with cadence, heartrate and power meters and you can really start to get a limitless possibilities, but we'll leave those for next year.
So I guess if you've read this far you probably want to see some detail shots.