# 7.3kg (16lb) Fairwheel Bikes Di2 mountain bike



## Ronin Six (Oct 1, 2009)

.
*$$$$ one-off. But pushing the limits on ride-able customization IMHO. Clean build tho for sure.* :thumbsup:

_*7.3kg (16lb) Fairwheel Bikes Di2 mountain bike*_
https://www.bikeradar.com/news/article/interbike-2010-fairwheel-bikes-di2-mountain-bike-27855


> In the absence of Shimano's still-anticipated release of an off-road version of their fantastic Dura-Ace Di2 electronic transmission, several companies and retailers have taken it upon themselves to create their own modifications.


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## culturesponge (Aug 15, 2007)

*genius*

really like the clean looks of this new Fairwheel Di2

electronics inside the stem is the perfect solution to all that electronic spaghetti of the previous Di2 Carbon Koncept - terrific! :thumbsup:


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## bhsavery (Aug 19, 2004)

Cool idea, very inventive and good way to minimize chain cross. But I kinda think there is a downside too right? Because if it's automatically doing a front shift when you might not want to do that. Also this would have to be programmed to a specific wheel size/gearing.

Either way I want to see more Di2 mt bikes!


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## facelessfools (Aug 30, 2008)

well with more people creating DI2 mt. bikes shimano may invest into it.


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## DeeEight (Jan 13, 2004)

It doesn't automatically front shift...it automatically trims the front derailleur to eliminate chain rub noises when you shift across the rear cogset. Road bikers don't have to put up with certain gear combos with the chain rubbing on the inner or outer derailleur plates because road front shifters never lost the trim setting half-clicks as mountain bike shifters did in the early 90s.


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## COLINx86 (Apr 8, 2009)

From what I understand it does automatically shift the front with the 'brain' they put in it.


> Sure, it's light and it's pretty with lots of anodised aluminium bits, but the key feature is Fairwheel's custom designed electronic 'brain' that turns the 2x10 setup into a trick sequential shifting system using just _one_ shifter.
> 
> In terms of user interface it's as simple as could be when set in 'race' mode: simply tap one button for an upshift and the other one for a downshift. According to Fairwheel's Jason Woznick, the custom brain calculates the gear inches and then shifts the front and/or rear derailleurs as needed to achieve the next logical ratio.
> 
> Duplicate gears are ignored, and Woznick adds that the programming is designed to minimise cross-chaining and front derailleur shifts as well. "As the bike sits, it's completely linear: two shift buttons, one for up and one for down," he said. "It can go from the 29/32T to the 42/11T, hitting all 13 equally spaced gears with only one front derailleur shift and without cross-chaining."


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## danridesbikes (Sep 10, 2009)

^^^ did you read the article?

it has sequential shifting


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## COLINx86 (Apr 8, 2009)

danridesbikes said:


> ^^^ did you read the article?
> 
> it has sequential shifting


Me or D8?
if your talking to me i did read it, my attempt at an explanation was just really bad.


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## danridesbikes (Sep 10, 2009)

DeeEight


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## facelessfools (Aug 30, 2008)

he meant d8.
the bike automatically goes to the next gear ration and skips repeat ratios.


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## Gregg K (Jan 12, 2004)

I laughed at electronic shifting until I realized just what it eliminates. Oh man, that is cool. I'd gladly dump my beloved dual control for something like this. That would break me free to get whatever brake system I want. 

Really cool.


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## wannabeRacer (Feb 9, 2004)

I like what I see


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## limba (Jan 9, 2004)

I don't understand what Shimano is waiting for. Everyone that has tried it loves it. They all say it's the greatest thing ever. People are modding it themselves for mtn. and cross bikes. It seems reliable, it can take a beating... I'm guessing 2013 we'll see it on mtn.bikes.


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## reformed roadie (Mar 30, 2008)

danridesbikes said:


> ^^^ did you read the article?
> 
> it has sequential shifting


It's electronic, sequential shifting...did you really think he'd get it?


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## DeeEight (Jan 13, 2004)

That's not a regular feature of Di2... that's something someone programmed up for this particular bike. Hence the word "custom".


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## reformed roadie (Mar 30, 2008)

DeeEight said:


> That's not a regular feature of Di2... that's something someone programmed up for this particular bike. Hence the word "custom".


Does anyone else enjoy the irony of the "doesnotplaywellwithmorons" under his name?

Of course it is custom...that was half the point of the article...
You still haven't answered the question re: if you read it.


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## DeeEight (Jan 13, 2004)

Nope, I tend to avoid reading bikeradar's articles.


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## facelessfools (Aug 30, 2008)

http://fairwheelbikes.com/cycling-blog/custom-bikes/titus-di2-project-29er.html


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## bhsavery (Aug 19, 2004)

DeeEight said:


> Nope, I tend to avoid reading bikeradar's articles.


And most of us tend to avoid reading your comments.

Back on the article though, thinking more about this, the sequential shifting would be a cool idea. I'm still a bit skeptical about the "unexpected" front shift. Meaning I wouldn't want that automatic front shift to come in the middle of an uphill. But I guess once you get used to the sequence it would be fine. This bikes need an LED display for the gear...


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## limba (Jan 9, 2004)

You can turn off the Race setting if you want full control over the shifting.


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## DeeEight (Jan 13, 2004)

Anyone who's actually attempted to double-shift in rough sections knows it increases the odds of a chain drop significantly. Sequential shifting might sound like a great idea on paper, but in practice... unless it puts the chain back on automatically also at the push of a button.


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## jeffscott (May 10, 2006)

limba said:


> You can turn off the Race setting if you want full control over the shifting.


That is what I was waiting to hear...

So you either get sequential shifting (not so good for me in my mountains)....

Or you can get separate control over fornt and rear perfect.


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## G-Live (Jan 14, 2004)

DeeEight said:


> Anyone who's actually attempted to double-shift in rough sections knows it increases the odds of a chain drop significantly.


That is true with mechanical shifting. The servos in the der's are so quick they overshift slightly and re-align for quick shifting as standard practice. Electronic MAY end up being quick enough and precise enough that it won't be a problem.

G


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## DeeEight (Jan 13, 2004)

Its not just the overshift, its the sudden change in chain tension from the rear derailleur moving at the same time as the front. If the next sequential gear requires the front derailleur to go from the outer to inner ring, at the same time as its going from a larger to a smaller cog, and the bike is bouncing over stutter bumps, the chain is likely to drop to the BB shell.


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## Ronin Six (Oct 1, 2009)

I haven't yet read the article at the Fairwheel site, but since the shift programming has been customized, would staggering the shift of both ders minimize the potential for dropping the chain? (ie front shifts first, then rear a second later)


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## trhoppe (Sep 3, 2008)

RTFA People



> Two buttons, one for an up shift and one for a down shift. The brain basically uses calculated gear inches to decide on the proper next gear. It's not as simple as a linear list though. The bike does not just run back and forth through pre-set options. It is configured to remove duplicate gears as well as cross chaining. But more importantly it reduces the amount of front chainring shifts it makes. If you are in your small ring and reach a point where it needs to shift the front to get a higher gear it does that. But then if you shift back to a smaller gear it does not return the chain to the small ring with the next down shift. It knows there are other options to get that same gear by staying in the larger ring and as long as one of those options does not create a bad chainline it will go for one of those. That means in moving from the lowest gear on the bike to the highest it only needs to shift the front derailleur once.


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## Ronin Six (Oct 1, 2009)

Not sure who or what you're addressing there, but I did RTFA on Bike Rumor, but not the one at the FairWheel site. Maybe you meant R both FA?
Maybe I'm missing the point, but the quoted paragraph above doesn't necessarily address the idea that the chain could possibly be dropped if both ders happen to shift simultaneously, right?

[edit] Ah OK, at least they're thinking about it...

From the Fairwheel article...


> *Other Shift Features*
> One other nice feature that Jeff built into this brain is the ability to dump gears. As a further improvement gears can be dumped as many as 13 at a time and in either the up or down direction. He opted to slow this dumping from it's full potential speed in to_* reduce the chance of dropping a chain*_. However, even in this slowed down mode it can go from the highest gear on the bike, a 42/11, to the lowest gear on the bike, a 29/32, in just over 1 second and without having to soft pedal... There are also other modes which will eventually be mentioned. Jeff, when asked, simply replied, "_if you can think of it, it can probably do it._"


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## nikoli8 (Mar 23, 2008)

It's just impressive... But off to the bike...
The crank...how heavies the front ring.. The shock boot...a tube, like Eliflap?


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## MessagefromTate (Jul 12, 2007)

DeeEight said:


> Its not just the overshift, its the sudden change in chain tension from the rear derailleur moving at the same time as the front. If the next sequential gear requires the front derailleur to go from the outer to inner ring, at the same time as its going from a larger to a smaller cog, and the bike is bouncing over stutter bumps, the chain is likely to drop to the BB shell.


Are you an EE with intimate knowledge of the programming and servo actuation etc, or have you ever even ridden Di2 for that matter? It's humorous you have so much feedback to an article you didn't read, or for a system that you haven't used yet when I look at the bikes you have built on that website linked by a certain Swiss guy your bikes weren't cool in 1992 let alone now...:nono:


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## Jake Pay (Dec 27, 2006)

nikoli8 said:


> It's just impressive... But off to the bike...
> The crank...how heavies the front ring.. The shock boot...a tube, like Eliflap?


Claimed weights: *http://fairwheelbikes.com/kcnc-blade-mountain-chainrings-p-2966.html*

Weight, 22 tooth: 17 grams 
Weight, 29 tooth: 20 grams 
Weight, 32 tooth: 33 grams 
Weight, 42 tooth: 69 grams
Weight, 44 tooth: 73 grams
Material T73 7075 aluminum​


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## peabody (Apr 15, 2005)

DeeEight said:


> Nope, I tend to avoid reading bikeradar's articles.


your moms calling, it's time for dinner! can you please stay out of EVERY thread?
not only is he an EE in this thread, but a materials engineer in another thread, there's nothing he doesn't do.


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## Jake Pay (Dec 27, 2006)

DeeEight said:


> *stop staring at willow's boobs *and pay attention to the bike parts.









what more is there to say....​


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## DeeEight (Jan 13, 2004)

MessagefromTate said:


> Are you an EE with intimate knowledge of the programming and servo actuation etc, or have you ever even ridden Di2 for that matter? It's humorous you have so much feedback to an article you didn't read, or for a system that you haven't used yet when I look at the bikes you have built on that website linked by a certain Swiss guy your bikes weren't cool in 1992 let alone now...:nono:


Oh is that certain swiss guy whining about me on other forums or his blog? I hadn't noticed. I haven't updated my webpage in gee.... well as far as bikes I own go.... let's see....

_Update : November 12th, 2005... as evidence that I haven't updated this section in a long time, the fact that I replaced the warp frame with an Oryx Hurricane 250 frame in september 2004 isn't listed, neither is the full suspension singlespeed I built myself in may 2005, nor the K2 Razorback full suspension loaner built june 2004, and its only now being updated as I've added another loaner to my fleet, in the form of a very light 14" Norco Sasquatch fully rigid build. Oh and my Ugly Ti road training bike is missing too I just noticed, hmmmm, guess that was sometime in early 2004 that I built it up to replace the UglyBik carbon. most of the same parts, different gearing, titanium frame. _

Ok so its been at least 6 years since any bike I built for myself got posted up there at the same time. Make whatever you want from that, but I'm not using my domain name to sell bike parts, or bikes, like that certain swiss does. I'm just squatting on it in case in the future I open a retail shop using that name but that's unlikely as I hit on another business name that works better for a bike store last spring. And if my partner and I get the financing together this winter, we'll open it with that name. Anyway the section of my page where I previously listed stuff for sale, was last updated 7 years ago and I actually deleted the whole page the button links to I think 5 years ago because I got tired of getting emails for things I didn't have anymore. I think the last time I posted in the tech tips section was 13 years ago... shall I go on ? Where is it written in the mtbr rules I need to have an up to date website showing my bikes for whiners who have nothing better to do than follow me around mtbr like cyber-stalkers?


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## eliflap (Dec 13, 2007)

chapeau !!!!!!!!


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## Hand/of/Midas (Sep 19, 2007)

Well, i have to say this bike is way more attractive then last years DI2 bike. i much prefer the lefty and Ti frame, much cleaner looking.

I'll still use cables till i die though.


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## limba (Jan 9, 2004)

Why?


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## DeeEight (Jan 13, 2004)

I'll wait for shimano to release the XTR/Di2. But having used both Mavic's ZAP rear derailleur system and the Suntour-Browning electric shifting crankset in the past, there's certainly potential for electric shifting mtbs. Personally I wish shimano had developed their airlines system into something for the front also, and replaced those damn rechargeable air cans with a straight screw in fitting for a co2 tank. I'd rather deal with pneumatics than things which release magic smoke when mixed with water incorrectly.


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## jeffscott (May 10, 2006)

DeeEight said:


> I'll wait for shimano to release the XTR/Di2. But having used both Mavic's ZAP rear derailleur system and the Suntour-Browning electric shifting crankset in the past, there's certainly potential for electric shifting mtbs. Personally I wish shimano had developed their airlines system into something for the front also, and replaced those damn rechargeable air cans with a straight screw in fitting for a co2 tank. I'd rather deal with pneumatics than things which release magic smoke when mixed with water incorrectly.


No need to have energy storage to shift gears.....

Electric needs it for the control, and shift energy, but the little battery could easily be charged from even something like a rev counter...

I would prefer a hydraulic shifter using common reservior with the brakes...done right the Springs could be placed in the shifter pods.

BTW just about everything will die when mixed with water improperly even pneumatics.


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## DeeEight (Jan 13, 2004)

Ironically we had hydraulic shifting derailleurs in the mid-90s...


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## jeffscott (May 10, 2006)

DeeEight said:


> Ironically we had hydraulic shifting derailleurs in the mid-90s...


Must have been executed poorly.


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## DeeEight (Jan 13, 2004)

S.A.F.E. Hydraulic shifters, they came out in 1995-96, and they just replaced the cable line from shifter to derailleur with a master cylinder you bolted to the existing shifter, and a slave cylinder that fitted to the derailleur. There were still cables involved but they were very short. The one in the shifter pulled the hydraulic piston in the master cylinder which pushed fluid down to the slave cylinder which then forced a piston to pull the short cable at the derailleur.

There's actually a more modern hydraulic shifter setup available in europe, that's 1500 euro for the two shifters and derailleurs.

http://www.5rot.com/preise.html

The company is german... and their site doesn't have an english side.


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## panhndl (Sep 16, 2009)

I've got a friend at Interbike. He said the bike is available for $45,000


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## DeeEight (Jan 13, 2004)

Yeah ok between that and the rebuilt 7 pound road bike, we're at half the price of a Bowler Nemesis, which is a heck of a lot more practical and fun.


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## MessagefromTate (Jul 12, 2007)

DeeEight said:


> Oh is that certain swiss guy whining about me on other forums or his blog? I hadn't noticed. I haven't updated my webpage in gee.... well as far as bikes I own go.... let's see....
> 
> _Update : November 12th, 2005... as evidence that I haven't updated this section in a long time, the fact that I replaced the warp frame with an Oryx Hurricane 250 frame in september 2004 isn't listed, neither is the full suspension singlespeed I built myself in may 2005, nor the K2 Razorback full suspension loaner built june 2004, and its only now being updated as I've added another loaner to my fleet, in the form of a very light 14" Norco Sasquatch fully rigid build. Oh and my Ugly Ti road training bike is missing too I just noticed, hmmmm, guess that was sometime in early 2004 that I built it up to replace the UglyBik carbon. most of the same parts, different gearing, titanium frame. _
> 
> Ok so its been at least 6 years since any bike I built for myself got posted up there at the same time. Make whatever you want from that, but I'm not using my domain name to sell bike parts, or bikes, like that certain swiss does. I'm just squatting on it in case in the future I open a retail shop using that name but that's unlikely as I hit on another business name that works better for a bike store last spring. And if my partner and I get the financing together this winter, we'll open it with that name. Anyway the section of my page where I previously listed stuff for sale, was last updated 7 years ago and I actually deleted the whole page the button links to I think 5 years ago because I got tired of getting emails for things I didn't have anymore. I think the last time I posted in the tech tips section was 13 years ago... shall I go on ? Where is it written in the mtbr rules I need to have an up to date website showing my bikes for whiners who have nothing better to do than follow me around mtbr like cyber-stalkers?


As I stated previously (and here's where reading comprehension comes in), your bikes were not cool in 1992, let alone now... The other point is to illustrate that while you act like you think you know what you are talking about you really don't. Your bike builds are a clear indication of that.


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## DeeEight (Jan 13, 2004)

And what bike builds and bikes of mine aren't cool are you referring to then? If you're such an expert on them....

I only owned one bike in 1992. What did you own for a bike in 1992 if you're the expert on cool?


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## COLINx86 (Apr 8, 2009)

http://fairwheelbikes.com/forum/viewtopic.php?f=49&t=7362
Interesting post from Madcow on this bike. 
DeeEight you should really read this one.


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## reformed roadie (Mar 30, 2008)

DeeEight said:


> And what bike builds and bikes of mine aren't cool are you referring to then?












I'll go with this one...:thumbsup:


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## limba (Jan 9, 2004)

Can we have a DeeEight hater thread stickied in some sub forum I never go in? If you guys want to fight pm each other or exchange phone numbers, no one wants to read it.


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## DeeEight (Jan 13, 2004)

reformed roadie said:


> I'll go with this one...:thumbsup:


Yeah cause you can build a 2x10 speed, 27.5er full suspension trail bike for under 25 pounds that'll hold up to someone who's over 200 pounds with riding gear, for less than $2800. Good luck with that.


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## TigWorld (Feb 8, 2010)

COLINx86 said:


> http://fairwheelbikes.com/forum/viewtopic.php?f=49&t=7362
> Interesting post from Madcow on this bike.
> ...


What an excellent read. I'm skeptical about the need for electronic shifting on a non-race only MTB, but it's always good to see a bunch of guys pushing the envelope.

What really sets a build like this apart for me is that its not just bolting together a bunch of off-the-shelf stuff. Let's face it, anyone who can use an allen wrench can "build" a bike, but the sort of things these guys get up to goes beyond that. They really did "build" some of the components (like the electronics) which is something quite different to someone just "assembling" a bike out of parts.


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## snowdrifter (Aug 2, 2006)

limba said:


> no one wants to read it.


I disagree, love the banter :thumbsup:


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## Madcow... (May 27, 2010)

Hi everyone, thanks for the kind words about my project. I thought I'd take a few minutes to answer some of the questions/concerns about the bike.



bhsavery said:


> Cool idea, very inventive and good way to minimize chain cross. But I kinda think there is a downside too right? Because if it's automatically doing a front shift when you might not want to do that. Also this would have to be programmed to a specific wheel size/gearing.


This was my biggest concern. Having a front shift when you were expecting a rear could screw up your rhythm. It turns out that it's not really an issue. The Di2 shifts so quickly and with so much power that you hardly notice it. With an XTR double crank it gets even better.
Switching between setups is an easy change as lots of different programs can be installed at once and changing is quick and easy.



culturesponge said:


> really like the clean looks of this new Fairwheel Di2
> 
> electronics inside the stem is the perfect solution to all that electronic spaghetti of the previous Di2 Carbon Koncept - terrific! :thumbsup:


The spaghetti of the Koncept was an unfortunate necessity. We used that bike to test many of the ideas that went into this one so to make changes easier we needed to have everything on the outside of the bike.



limba said:


> I don't understand what Shimano is waiting for. Everyone that has tried it loves it. They all say it's the greatest thing ever. People are modding it themselves for mtn. and cross bikes. It seems reliable, it can take a beating... I'm guessing 2013 we'll see it on mtn.bikes.


Shimano feels that it isn't ok to have a $900 derailleur being smashed against rocks. So until they get the price down and or find a way to protect the derailleur, don't expect to see an official mtb version.



DeeEight said:


> Anyone who's actually attempted to double-shift in rough sections knows it increases the odds of a chain drop significantly. Sequential shifting might sound like a great idea on paper, but in practice... unless it puts the chain back on automatically also at the push of a button.


While the gearing may be sequential the shifting is not simultaneous. For example when a front shift and 3 rear shifts are required it staggers them. It will shift one rear, then the front then two more in the rear. The rear shifts so fast that it's only the front you notice. We are re-timing the rear to move even quicker as we have intentionally slowed it down from it's full speed.

Also because the system doesn't allow crosschaining we can run a shorter chain which means more tension on the chain. And since it doesn't allow a small/small gear combo it never runs in the position of most slack either.

It is also designed to minimize front shifts. It doesn't just run through some preset positions. It knows if you are in the small or big ring and chooses gears to keep it in that ring for as long as possible until the chainline is no longer acceptable. Going from the smallest gear 29/32 to the largest 42/11 it uses 13 different gears, it can do all of those with only 1 front shift. So minimizing front shifts also minimizes the chance of dropping a chain.



G-Live said:


> That is true with mechanical shifting. The servos in the der's are so quick they overshift slightly and re-align for quick shifting as standard practice. Electronic MAY end up being quick enough and precise enough that it won't be a problem.
> 
> G


You are certainly correct that it shifts quickly. It's not just the servos though as the derailleurs also use springs to increase force. The front for example if you were to take out the servo you'd still have a spring driven rapid rise front.



Ronin Six said:


> I haven't yet read the article at the Fairwheel site, but since the shift programming has been customized, would staggering the shift of both ders minimize the potential for dropping the chain? (ie front shifts first, then rear a second later)


Yes, it made a difference, and is in fact how it works. Though staggered rear/front/rear.



nikoli8 said:


> It's just impressive... But off to the bike...
> The crank...how heavies the front ring.. The shock boot...a tube, like Eliflap?


The front ring is actually pretty light, and one of the stiffest ones we could find outside of an XT/XTR. The boot is a tube. A butyl tube would work better than our latex as it would be a looser fit but ours works ok, it just requires more maintenance to keep it moving without sticking. The cannondale factory riders have been using tubes in place of boots for a while.



DeeEight said:


> I'd rather deal with pneumatics than things which release magic smoke when mixed with water incorrectly.


The Di2 stuff works even when completely submerged in water. I'm told it's been tested to 10m, but I doubt my bike will ever be that far underwater.



jeffscott said:


> I would prefer a hydraulic shifter using common reservior with the brakes...done right the Springs could be placed in the shifter pods.


Not that it has a shared reservoir with the brakes, but 5rot has a really nice hydraulic shifting system.



panhndl said:


> I've got a friend at Interbike. He said the bike is available for $45,000


That's actually incorrect. We figure without the cost of R&D for the brain the bike is probably around $12,000. The number he gave was for the 6 pound road bike, but again that wasn't an official number for that bike either, just something that someone tossed out as a rough guess but probably quite a bit inflated. I think the point of that number was to say that you can't build the bike because everything on the 6 pounder was a one off and you can't just call up most companies and ask them to build you a one off.

We certainly aren't done developing this Di2, we have quite a few new additions that we came up with but didn't have time to finish before the show. Perhaps at NAHBS you'll see the next version.


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## markw1970 (Oct 8, 2007)

Super stuff Madcow - just the sort of thing I want to read here. Thanks


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## limba (Jan 9, 2004)

Nice. Looking forward to any future improvements and problem solving.


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## reformed roadie (Mar 30, 2008)

*+1*



markw1970 said:


> Super stuff Madcow - just the sort of thing I want to read here. Thanks


Good to read some more detailed explanation.

The one question I have is about the frame; why the Titus? Seems there are other carbon options that might be more suitable. Just the neighborly thing to do?


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## Madcow... (May 27, 2010)

reformed roadie said:


> Good to read some more detailed explanation.
> 
> The one question I have is about the frame; why the Titus? Seems there are other carbon options that might be more suitable. Just the neighborly thing to do?


The original design called for a different frame. We were going to unveil a carbon 29er from someone but in the end the frame wasn't finished in time. Titus being a group of really nice guys were able to step up and get something done in the one week time frame we had. That's the reason that they had to do the round tubes instead of the hydroformed was that they just didn't have the time to do the hydroforming. It's also why not everything is internal as there just wasn't time.


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## panhndl (Sep 16, 2009)

I'm with you Madcow. My friend and I were texting back and forth and I told him I wasn't disappointed I didn't get to go to Interbike since I was able to buy your uberlight mtn bike.

He was stoked until I let it slip that a) I didn't buy the bike and b) I wasn't even sure it was for sale. Later that night he texted me that it cost $45,000. Just reporting what he sent, heh.

And, while I think the bike is awesome and believe that things like this are where future products for dorks like me come from, $45,000 (or whatever the price really would be) is beyond what I would be able to chalk up to a "good buy" to my wife. If I bought that, 1st she'd prolapse, 2nd she'd castrate me, and 3rd she'd demand a very new and very expensive car. 

Regardless, kudos to Fairwheel bikes for building uber not once, but twice in one year.


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## Gregg K (Jan 12, 2004)

I was just thinking about hydraulic shifters as I was riding up a trail yesterday. It seems everything has been done already.

Madcow, I like the shifting project. I missed what battery requirement there is. That has to add some weight to things.


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## Madcow... (May 27, 2010)

Greg the battery is one that we had custom made to fit inside the seat tube. It has the same specs as the stock Shimano battery but is lighter. Overall this is about the lightest group you could put together. For sake of comparison here it is along side a XX group.

Sram XX
shifters(213), front derailleur(119), rear derailleur(180), chain(261), cassette(186) shift cables and housing (89) Total weight for that kit is 1048grams.

My kit.
Shifter(11), front derailleur(117) front derailleur clamp adapter (15), rear derailleur (215), chain (236), cassette(sram XX because XTR was not available 186) rear wire kit (54), front wire kit including the brain(16), battery (41) Total weight for that kit is 891grams.

I tried to keep a pretty level comparison between the two. The XX could be tuned a bit and might get close in weight, but it will do so at a performance penalty.


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## Gregg K (Jan 12, 2004)

I really like this. I do wonder just how long it would work before a recharge in the event that there was a bunch of shifting. Whole cassette swings. Not all chainring shifts are crisp and quick sometimes. I'm sure you've spent time on the bike, and know all of this stuff. 


All I know is I want this setup.


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## Epic-o (Feb 24, 2007)

Madcow, just one question. How do you control the speed of the shift when you change multiple gears at the same time? For example, when you shift from 42x21 to 29x15, you have to change two gears rear and one front. In a standard system, you are limited to the speed of your finger buth with this "brain" no. Does the brain check if the first shift is completed with the torque sensor and then sends the second signal? Can the derrailleur cope with two consecutive signals before it has been able to do the first shift? Do you know the fastest shift speed possible?

Uh...that is more than one question


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## Rod (Oct 17, 2007)

markw1970 said:


> Super stuff Madcow - just the sort of thing I want to read here. Thanks


Agreed. Great post


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## DFYFZX (Jun 19, 2009)

The only part of the whole build that concerns me is drilling holes in a carbon stem! Is that really a good idea? The EDGE carbon isn't even the lightest stem you could have used, unless it was a freebie from a sponsor My aluminum Sunline stem, or the new KCNC stems, are lighter and have just as much room inside without possibly screwing up the layup of a carbon piece. I'm assuming you checked with EDGE to make sure it was safe???


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## COLINx86 (Apr 8, 2009)

DFYFZX said:


> The only part of the whole build that concerns me is drilling holes in a carbon stem! Is that really a good idea? The EDGE carbon isn't even the lightest stem you could have used, unless it was a freebie from a sponsor My aluminum Sunline stem, or the new KCNC stems, are lighter and have just as much room inside without possibly screwing up the layup of a carbon piece. I'm assuming you checked with EDGE to make sure it was safe???


IIRC, the Edge stem was custom made for them, So I wouldn't be surprised if Edge drilled the holes for them.


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## limba (Jan 9, 2004)

limba said:


> I don't understand what Shimano is waiting for. Everyone that has tried it loves it. They all say it's the greatest thing ever. People are modding it themselves for mtn. and cross bikes. It seems reliable, it can take a beating... I'm guessing 2013 we'll see it on mtn.bikes.


WRONG! This took 4 years to actually happen. I wonder what a stock 2015 Cannondale Black XTR Di2 weighs ...


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## phlegm (Jul 13, 2006)

Ha, love the selfie quote necropost!


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## maynard (Jan 15, 2004)

could this be DEEight, he or she has been a staple of the internet since MTBR and pinkbike was invented

Robert Campbell, international cyberbullying suspect, back in court - Ottawa - CBC News


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