chojn1

Hi all,

With my DIY bike completed, I now have a spare tandem to ride. Unfortunately, with all the rain we're having the last few days, that too is put on hold.
So I have been thinking about pulling my road tandem in the shop for and upgrade: a DI2 conversion.

I'm looking for recommendation from current DI2 riders.

1) Send the frame back to the builder for internal routing or DIY external routing? How does internal routing work on a coupled tandem? How do they deal with the eccentric on the internal routing?

2) As I see it, the current tandem triple must be modified to work with the DI2 front derailleur. Which is the better approach? a) take off the inner ring of the triple and find an extended derailleur clamp, b) modify a single bike's triple for same side timing belt, or c) convert to a compact double.

3) 10 or 11 speed?

Thanks in advance for your help.
CJ

Bezalel

What is your current crankset? Normally I'd say to remove the inner ring and shorten the spindle by 5mm.

chojn1

Bezalel,
I am currently running a FSA SLK set. I only have one spacer on the drive side, so the most I could reduce the spindle length is 2.5mm. If I take the remove the inner ring approach, do I still have to find another extended derailleur clamp, or will the current FSA tandem clamp do?
Thanks,
CJ

Bad1

If your rear spacing is 145 you will need a extended clamp:
https://www.bikerumor.com/2013/09/24/...cchiato-tandem
Comotion makes one, similar set up to what you talking about, FSA makes one, I finished a new DI2 build in Dec. had to use a extended clamp.

chojn1

Yep, my spacing is 145. Any idea at the width of that extended clamp? My old Dura ace triple clamp is 4mm from the edge of the seat tube to the edge of the derailleur; the FSA tamdem clamp is 8mm. How much more is the extended clamp?

The reason I asked is because I want to make an attempt at fabricating one this weekend if I know the measurements.
Thank you so much.
CJ

akexpress 

You built a custom frame, don't stop there do an internal routing on your existing frame yourself. I am on my fourth custom internal routing and it is not that hard. I sent you a pm with my contact info for any questions you might have. The couplers and eccentric are not big problems just requires a few extra connectors and wires that are all pre made and available. As I stated on the previous thread 10 speed has more options for rear cassettes and able to use existing wheels sets. Plus 10 sped prices are good right now.
Mark

twocicle

I have the perfect new thread for you... coming soon (ie: this weekend). I am waiting for a couple parts to come in today & Saturday before wanting to post my finished Ultegra Di2 10spd setup on our 145mm spaced, S&S coupled Calfee. Same-side gates belt, regular/non-tandem FSA SL-K cranksets. Pricing on Ultegra Di2 10spd has become much more affordable in the last 6 months. I have photos of how Calfee modified the front and rear BB shells to route the Di2 wiring. Couplers make accessing the wiring all that much easier, but not really necessary due to additional access via the BB shells and rear seat tube. You can toss in as many 4-port "B" (rear) junction boxes and wire segements into the mix as you wish, which is done in this case to take apart a coupled tandem.

Meanwhile, for Di2 chainrings (only 2 rings are supported) you will need to determine what combinations you need. If you need to keep your granny gear, then you must use the middle ring position for your big ring. However doing that can have some issues such as chainring bolt clearance between the big ring and granny due to the big ring not having recesses on the inside. Some of this can be solved by using spacers and longer ring bolts. Otherwise you could run just the outer two chainring positions, ie: 53/39. I implemented your option B and elected to use 48/30 chainrings.

LastKraftWagen

Twocicle- Question about your choice for chainrings...Did you have any problems with the DI2 FD working with the 48-30 chainrings? Shimano tech specs (and I don't know why I would follow these when I ignore so many others) quote the FD "capacity" at 16 teeth; and do have an issue with the FD arc on the 30T chainring? For that missing outer ring issue, when I rode trials we use to grind the teeth off the outer ring (since we didn't need it anyway) and use it as a "outer chainring guard," or in the case of a road bike, an outside chain catcher of sorts? At one time some manufacturers actually made "fit and finished" outer toothless rings.

chojn1

Mark,
Your enthusiasm for the DI2 system was what got me thinking about my conversion. Grateful for your help. I am racking my brain right now, but cannot figure out how to get around the eccentric through the shell. The stock eccentric I have does not leave any gaps like the BB does. Even drilling into the thing would leave certain segment of the eccentric completely blocked. Let me know about your solution.

Also, I don't have any problem drilling into the frame, but how do you build support around the holes?

Twocicle,

I can't wait for your post. What good timing!

LastKraft,
I am guessing of course, but I think in his configuration, the outer chain ring is removed and replaced with a timing belt pulley. I am also curious about the chain rings. I thought about doing the same, but was dissuaded by the specs which also called for a minimum 50t outer ring. I guess the code is "what you'd call guidelines than actual rules."

Where I live, there are no hills, so I'm never in the granny. But when we travel, we cannot do without. So eventually I will need to switch to the compact crank, but for now I will just experiment with the 39/52 outer rings. Regardless if the routing is internal or external, I still will need that extended derailleur clamp.



I played around with the design today and printed out a mock up that will give me an extra 2.5mm gap outboard (10.5 mm from the edge of the down tube and the derailleur). Hopefully this will be enough. Will layer some carbon tomorrow if I find some time.

CJ

akexpress 

On our coupled Calfee we use a Bushnell eccentric that actually has space to run a wire over much like a regular bb crank spindle. Also a slot can be cut in the shell to put the wire in secured by silicone. this does not affect the integrity of the bonded BB shell at this point. As far as holes in the frame it doesn't appear even the factory DI2 frames are reinforced in the areas of grommets, and in fact the grommets are not designed to accommodate very thick frame materials. In some refits the mechanical cable stops like on the chain stay are actually riveted in (on some carbon frames) and you can drill out the rivet and use it for the exit hole. A brake or Derailleur cable and some dental floss is a great way to snake the wires through the very small hole. I used a small piece of plastic and practiced making holes to get the correct shape for the grommets and then made a template to transfer the shape to the frame. I use a dental hand piece to make the holes but one could use a dremel with a carbide round burr to do the same. On a coupled tandem I think the stokers seat post is the best place for the battery and has a 4way junction at the base of the stoker seat post for all the connections. As all the new Di2 use the e-wire system that is simply a coaxial wire you can plug any wire into any empty port on a junction box or shifter and everything talks to each other. The internal routing makes the bike have a very clean look and now that shimano makes all the components for it there isn't any hacking necessary . When we converted our Calfee we had Shimano Cranks and they do not allow for opportunity for compact gearing in any configuration so switched to Lightning cranks at that time. BTW K-Edge makes a extended front derailleur hanger also even thought it is not shown on the website( I have a couple so I know they exist).

twocicle

No problem shifting the FD between the 48/30 even though the gap is 18T, the granny is small, and I poked my eye out repeatedly while installing... [joke]. The Di2 FD can apply very strong side load forces, so you need to take care on initial setup to adjust the FD range so as not to let it bend your big chainring, or push too hard on your seat tube. Calfee actually added a lot of carbon wrap to my seat tube under the RD clamp area for reinforcement for this very reason. If you can use the standard Shimano Ultegra Di2 FD clamp, I highly recommend it because the design provides a nice wide load plate and incorporates the stop plate for the FD set screw.

BTW, I am also able to use a 11-34 cassette by simply swapping out the RD-6770 cage using "mid-length" cage parts from a RD-6700A GS ($30 Shimano), a 10 tooth upper jockey wheel, and a longer "B screw" reversed so the head is against the hanger/dropout lip (Speedplay Zero cleat screw has a wide head and same threading - worked perfectly). I went a little high-end on the jockey wheels using KCNC w/Ceramic bearings (see https://fairwheelbikes.com/ and try to look past the CyclePassion calendar photos)

With the same-side drive setup, one thing (out of many) that popped up was access to the eccentric adjustment screw. Bushnell/DaVinci to the rescue... this eccentric can have the adjustment screw reversed to the non-drive-side by simply disassembling (per Bushnell's maintenance instructions) and rotating the clamping "wings" 180 degrees, then reassemble. Obviously you can't simply install an eccentric backward because the BB cup threads must be on the correct side (FSA BB shells are side specific - different thicknesses). You wouldn't want to install other BB shells on the wrong side either, because they could unscrew (like Italian thread BBs sometimes do, then you have to use locktite).

I had a great time putting this all together as an experimental project. A lot more "solutions" to discuss.

LastKraftWagen

LastKraft,
I am guessing of course, but I think in his configuration, the outer chain ring is removed and replaced with a timing belt pulley. I am also curious about the chain rings. I thought about doing the same, but was dissuaded by the specs which also called for a minimum 50t outer ring. I guess the code is "what you'd call guidelines than actual rules."

Where I live, there are no hills, so I'm never in the granny. But when we travel, we cannot do without. So eventually I will need to switch to the compact crank, but for now I will just experiment with the 39/52 outer rings. Regardless if the routing is internal or external, I still will need that extended derailleur clamp.

I'm actually considering DaVinci cranks with the swappable spyders. Then (if it all will work) I could swap between standard 53-39 and 50-34 for the hills. If the FD works okay with even smaller rings I may also consider the smallest spyder (MTB rings?). If I've thought it out right, it would be a simple spyder and chain swap and sliding the FD clamp up or down....Of course, best laid plans and all.

LastKraftWagen

[QUOTE=twocicle;16535262]No problem shifting the FD between the 48/30 even though the gap is 18T, the granny is small, and I poked my eye out repeatedly while installing... [joke]. The Di2 FD can apply very strong side load forces, so you need to take care on initial setup to adjust the FD range so as not to let it bend your big chainring, or push too hard on your seat tube. Calfee actually added a lot of carbon wrap to my seat tube under the RD clamp area for reinforcement for this very reason. If you can use the standard Shimano Ultegra Di2 FD clamp, I highly recommend it because the design provides a nice wide load plate and incorporates the stop plate for the RD set screw.

BTW, I am also able to use a 11-34 cassette by simply swapping out the 6770 RD cage using "mid-length" cage parts from a 6700 GS RD ($30 Shimano), a 10 tooth upper jockey wheel, and a longer "B screw" reversed so the head is against the hanger/dropout lip (Speedplay Zero cleat screw has a wide head and same threading - workd perfectly). I went a little high-end on the jockey wheels using KCNC Ceramic (see https://fairwheelbikes.com/ and try to look past the CyclePassion calendar photos)
Yeah, I went the simple [read as expensive] route and purchased the K-Edge KI2 conversion. No flipping of the "B" screw and it will handle a 36-11 cassette and 44-tooth capacity.

akexpress 

Another albeit expensive option is the Lightning Cranks that also have a interchangeable spider. They have a simple solution to achieve the correct chain line as they have a spacer that goes in the spindle connection to widen the crank spindle length. We have not had any issues with these cranks and they are very light. It is easy to change out the spider however we have been satisfied with compact and 11-36 at this point.

chojn1

Mark,
I finished the derailleur clamp. It is about 5 gm lighter and 2.5mm wider than the FSA clamp. It is also tall enough for the DI2 FD pivot screw. So I can save some weight on the backing plate. Hope it works.
I am waiting for some cutting oil before I start drilling into the frame. I've picked out a place on the chain stay, front and rear seat tubes. The area between the bottle mounts should have a little better support as not to disrupt the frame integrity too much. But I cannot decide on where to put the hole on the down tube. Where is the best place to drill? Also any advise on how to drill titanium? The frame shape is too awkward to fit on my drill press, can I just freehand it?

From Twocicle's post I will also need to work on making a grove in the eccentric shell.

Regarding the cranks, I would love to have an American made crankset. But, that cost is prohibitive for me. I'll use my current crankset for now, and will upgrade when possible.

CJ

akexpress 

Here is the most recent BB shell I modified to run the wires. As this Calfee frame has a coupler right in front of the bottom bracket I am putting the 4 way internal junction box in the lower tube between the coupler and the BB. By ordering long enough wires I am able to run wires to the rear derailleur, FD and seat post battery and have the connection to the front of bike available to take apart the bike. This eliminates one junction box and also allows smaller holes in the BB shell as you don't have to be able to fit a junction box up into the seat tube. This is a titanium BB shell where all the others I have done were aluminum but it was not that much more difficult to modify. This bike uses SRAM cranks so there is probably a little more room for the wires in the BB and maybe you could get away without the slots but it would put more stain on them. As usual running the wire in the chain stay is the most challenging due to size constraints of the tube.

twocicle

I'm not sure why Calfee insisted on drilling the same size holes in our frame as what they might do for a non-coupled version. I agree that large holes in the BB shells are not necessary for coupled bikes which have easy access to make wire joins in the bottom tube.

I am converting our Di2 wiring to use only 2 B-Junction boxes instead of the 3 that was installed "at the factory". I will leave 1 B-box in the bottom of the rear seat tube (connecting the battery and both derailleurs) and running one 850mm wire to the front B-box installed in the bottom tube at the front coupler. There will be plenty of wire slack available to make assembly/disassembly easier. From the front box a single 1000mm wire runs up to the A-box installed on the captain's stem.

For the rear FSA BB, we have the 8681 which comes with a smaller Mega Exo axle cover, allowing Di2 wires more space to run over the mid point.

waynesulak

Impressive carbon clamp. Did you build a mold/press out of wood?

I don't recall what fork you have but just in case it is tapered,
i have seen photos of internal wiring going in an oversized head tube then through the main tubes. Takes advantage of the space around the narrow part of the fork steerer.

DrMarkR

So in an FSA MegaExo triple crankset, is it acceptable to move the spacer from the right to the left, to bring the rings into the adjustment parameters of the DI2 Front Der? I trialed it tonight on my Robusta and it looks like it's going to work fine....plenty of crankarm clearance.

Since we have a Gates belt, I'll likely to the same to the captain's crankset, to keep the belt alignment.

Any input would be appreciated.

twocicle

If you are using a FSA tandem crankset, they made it compatible with 68-73mm BB shells by adding 2 spacers per BB and advertise "Unique spacer system allows chainline adjustability". I have the tec docs but not the direct link to FSA. The install doc says you can put those spacers where you like, typically depending on what you want for a chainline. So... 2L, 1/1, 2R... it's up to you.

Chris_W

If you do this and want to keep pedal spacing similar on both sides then put a couple of pedal washers behind the right-hand pedals. However, even if you don't do this then I'd be surprised if you noticed the difference in pedal spacing.

DrMarkR

Thanks! I'll post some pics of my setup later today in the other thread I started....

MR

chojn1

I just came back from our ski trip, so not much progress on my DI2 install. I did manage to drill all the necessary holes before I left. I was nervous about drilling into the frame, but after the first hole the rest came very easily. Some masking tape, center tap, cutting fluid, progression of drill bit sizes and about 30 minutes was all it took.

On the plus side, all the parts I ordered were sitting on my desk on my return, so I am ready for the install. The first challenge:



Unlike the carbon frames, mine has a gap in support from the captain seat tube to the boom tube. A grove in the shell will leave a hole at this point. Instead, I am looking into modifying the Bushnell/Da Vinci eccentric. A Cannondale eccentric would have been easily installed here, but there are just too many complaints about the thing getting stuck.

The second problem is the rear bottom bracket. There is a lip on the sides of my bb axle cover. Problem solved with 5 minutes on the belt sander.


Regarding the drive train, I have on order an FSA SLK Force compact crankset (50/34). The 172.5mm length of the cranks matches the current front and rear tandem crankset. The plan is to replace the right cranks with this set. This will eliminate the need for modifying the driveline, or the extended derailleur clamp. This is a little unfortunate, as I will not be testing my new carbon derailleur clamp.

chojn1

The mold for the clamp was made with a 3d printer. This is much faster, and much more precise than the wood I used to use.


This is the same technique I am using for my new DI2/Computer mount:


It is raining again today, so I should have plenty of time to finish the install. Hope it will let up enough for a test ride later.

CJ

twocicle

Are you certain a normal/single crank axle will mate with your left side tandem crank?

AFAIK the splines are different.