shlammed

Thanks, I don't even really need syncro shifting. I just want the means of the system to totally shut out the 53x40 cross chain, since even though it fits within the parameters when using a roadlink, think it would damage the RD with extended use.

Im going really wide range double with 39/53 crankset and 11-40t cassette.

Turbotandem

The frame was $7,200 including all the custom upgrades (60mm downtube, swept stays, internal wiring ready, and 44mm headtube). That includes a headset which gets mounted in the frame, but without fork and without paint. The painted frame came in at 6.3#, just a bit heavier than the usual Paketa.
The completed bike was around $16,000 using a lot of self-procured pricing and a few items I had on hand, and no cost for the assembly. That's for a no-expense-spared approach including every ti bolt for mounting every item, several out-of-production items, and every custom fabrication (carbon stoker stem, areo bars, custom laced wheels, etc.) With less customer involvement the same spec would be more like $18,000. That's not including the bags and camping gear on the bike. The bags were $680. I've got a 300 line spread sheet of the build if you need that level of detail:

https://docs.google.com/spreadsheets...it?usp=sharing

Turbotandem

Finally got the custom Black Sheep titanium fork mounted on our tandem. I am super pleased with the ride! 70mm offset on a cyclocross length 410mm AC is a geometry you'll only see on a tandem, and only with a custom built fork. Max offset you can get premanufactured is 40-45mm. The 70mm could have been found on french racing tandem in the 40's, where it performed well, and I find is is stable standing in the climbs, the low flop is evident, and comfortable on fast washboard. The low flop will be more important as we load up the bike and the front end for bikepacking. I think James picked just the right tube diameter and gauge for the 410mm legs. We'll still use the Whiskey no 7 cross carbon for climby ultra-road events. The Black Sheep fork came in at 900g, and includes cup drop outs, tapered steerer, and two bottle mounts and two anything-cage mounts on the legs. Clears the 700x43mm Bruce Gordon rock n roads with ease and will clear 29x2.2" for tour divide. Not to mention the 70mm offset provides the toe clearance I need for the gravel geometry we developed for the frame. It's all come together nicely!

If any of you are counting, this one picture has a barrage of tandem specific and custom work
- Custom 70mm offset Blacksheep Ti fork, tapered Ti steerer
- Custom geometry frame and you see here the 44mm straight head tube and 60mm down tube (Mg frame)
- 1.5" headset
- Nox Composite A36D rims, hand built to tandem tension (Tubless Bruce Gordon tires)
- Drop UI2 levers (mated to XTR rear DR out of view)
- Custom Leather wrapped bars
- Custom Velo Zephyr modified CGT Jammer Aero (Out-of-production) bars on Jtek stem face plate (Out-of-production)
- 200mm rotor, TRP Hy-Rd caliper
- JPak custom bolt on frame bags
- Did you glimpse the Power Cordz corrosion proof, black rear brake cable special order tandem length? (Saves 20 grams as well). The front is cable since it's so short

Don't get me started about the work on the back half of the bike.

twocicle

We were thinking of your sans-pavement beast this last Sunday in Walla Walla as our skinny 28mm tires were slipping while climbing >10% gravel pitches using a 30x28t ring setup. Plus, we could have used your bags to accumulate wine bottles from the tastings While packing for the trip, I completely forgot to grab any of our racks or frame bags :/

FWIW, Walla Walla has some great riding with miles and miles of gravel roads venturing to far off horizons.

What did your net trail and flop values end up as?

Bicycle Trail Calculator | yojimg.net

Turbotandem

Compared to the whisky fork 43mm offset on 396 axle to crown, the new 70mm offset 410 axle to crown, that has reduced trail from 65mm to 37mm and reduced flop from 18 to 10. That's with 45mm tires. With
2.3" tires the trail is 41 and flop 12. Any single joke maker would balk at a trail much under 50 as the trail reduces the bike can be dangerous at high speed. But on a tandem somehow the wheelbase of the bike has actually made the bike much more confident with less trail.
Note that the increased offset also added additional clearance over the top of the tire for larger tires because as the offset increased the axle to crown had to increase to maintain the same bike stance. Win win.

colotandem

Turbotandem, your bike wins!

I'm torn whether you should paint the fork or leave raw... There is no right answer.

twocicle

Andy, can you post all the firmware versions you have for your "synchro enabled" road/mtn setup?
View in e-tube without performing any updates.

waynesulak

Great to see a high tech low trail tandem. Very much agree on the trail setup. It works great on a tandem with 38mm+ wide tires. In my mind the steering tube angle + fork offset makes up at least half the ride characteristics of the bike. Very stable if the captain uses a light touch. Some captains like to constantly squeeze the bars and the bike quickly responding to constant small back and forth steering makes the bike feel unstable.

Turbotandem

I checked tonight and the e-tube software tells me the firmware of certain components is out of date, but it does not say the version. Maybe if I hit the button that says "update" it would but I don't want to risk upgrading and messing things up.
While I was at it I grabbed a screen shot of the syncro-shifting map. I've adjusted it a few times in e-tube. I have a screen shot below of the out-of-the-box map, and an excel grab of my adjusted map. There is not a way to tell e-tube another gear set than the stock shimano configuration, which I do not have, so I made my own chart to make sure I picked the right shift points for my gears. My general approach is once I am in a chainring, let the shifting allow the chain to remain in that ring as long as possible. I can always force a chainring shift if I like, such as cresting a hill knowing I wont a bigger ring soon. I also don't love two cog shifts while the chainring is shifting, so I limited that. I also have two shift maps, one for hillly courses favoring bigger steps and staying in the smaller rings, and one for flat courses favoring tighter shifts staying in larger rings. As noted in a follow-up post, the grey areas are default dos-allowed cross chaining gears the di2 won't allow.

colotandem

Andy, it sure sounds like you have it dialed!!

Someday maybe I'll learn about this electronic stuff... until then, it is like I am reading a foreign language! I realize that I am missing out on some cool technology, but don't want to open pandora's box - I'm sure that would be an expensive proposition!

twocicle

Just do the "Connection check" and proceed so the device map displays on the right of the screen. Then click each device green box to display the firmware versions. No need to touch the "Firmware update".

On another topic area, I am considering a "trekking" triple 48/36/26 ring combo for our next drivetrain setup. That is apparently a fairly standard triple offering and still seeing it available in Europe. ie Shimano Deore XT FC-T781, for a 104/64mm BCD. However the XTR Di2 reports say the big 2 rings should not be more than 10 teeth diff. Have you tested >10 teeth diff?

Turbotandem

I like it, along the same lines I was thinking for our back-country rig needing lots of gear when loaded. My feeling is that the teeth difference is based on chain wrap, which is fully solved by synchro shifting since you can't cross chain if you program it so. And based on shimano wanting set ups with high shifting performance. I am on a 22-34-44, which is out-of-spec in terms of total teeth (Shimano specs 22-30-40). I am certain the FD would work with a 48t even if it grinds a little more in the shift than a spec 10t change and you would actually have less total chainring teeh change from low to high as on my set up. But I've not tested a 48t. And remember, I am on a 10-42 cassette, which is even more teeth variation than the Shimano spec 11-40 cassette. I went with the 10t small cog to get the same top end you're describing with a 48t chainring. But of course to get the 10 means a specific set of wheels with the hub that suits that SRAM special fitting. Some hubs have an interchangeable body, but just heads up as you spec your build if you go that route.

When I was designing a set up, I challenged whether I'd need 48t, especially with a 10t cog; if one is touring loaded will you really crank it up to high speed? A 44t with 10t cog, or a 48t with 11t cog both spin out at 35mph with a cadence of 100 (or 38mph at cadence of 110). Touring or on gravel, that's a fine top end. A 48t with 10t cog you spin out at 38mph, gaining only 3mph. For me, those 3mph were not important for what will be pretty rare conditions on a straight away down hill. So I chose better shifting for what is 98% of the conditions I encounter.

twocicle

We have been riding a lot more this year with 11-32 and 11-36 (Mallorca) cassettes, but sure don't like the wide gaps in cogs. Linda doesn't have the torque power to contribute much when our cadence slows, so we do best when spinning a lighter gear and the jumps between are small. Likewise we can only use the final 48x11 (52x12 equiv) when accelerating on a downhill, after which it's time to speed tuck and enjoy the coasting. With any sort of high load riding, Linda very quickly develops various pain issues.

Using my favorite gear calculator, I think the best combo for us would be to drop the 26t ring in preference for a 24t giving a 48/36/24 combo (a 24t total ring difference). Then either a straight 11-23 cassette (matching our usual 48/30 with 11-28 cassette range), or for severe climbing where we currently might use a 11-36 the new triple setup would only require a 11-28 cassette to achieve very close to the the same low gear and a lot closer ratios.

The current fad to have 1x11 or 2x11 super-wide gearing is total crap IMO. No personal offense to anyone intended. Just my take on the gearing trend.

If Shimano would cough up a Di2 road triple FD, that would be huge. Otherwise XTR is the only option (XT Di2 just came out, but with only the smaller rear cage and a double front - no triple).

---

Just found this article discussing the XT T8000 "Trekking" crankset (pretty much the same as the FC-T781 with 48/36/26), so it looks like Shimano won't totally do away with triples just yet. It is odd though that the XT Di2 has no triple option.

Turbotandem

SC-M9050 version 3.0.2
SM BTR2 ver 3.0.10
ST 6770 ver 1.0.1
RD M9050 SGS 3.0.7
FD M9050 ver 3.4.1

twocicle

I am still in the process of converting our cranks and derailleurs to a triple setup, but did some preliminary fiddling with the XTR Di2 (+ XTR display and the r785 hydro brake levers, and my original BTR2 internal battery). All components and e-tube software are updated to the latest versions and everything seems to work as expected... ie: synchro functionality (custom mapping and shifting) works fine with the road shifters.

One odd thing I found with the e-tube software and the XTR derailleur config, is the lack of derailleur adjustment via the software. With the road (Ultegra 6880) derailleurs I can adjust both derailleurs via either software or manually using the front junction (or display) and the shift paddles. For some weird reason with the XTR derailleurs I can't seem to find the software method, leaving only the manual approach. Maybe I missed something... it's been known to happen.

The synchro functionality is interesting. I haven't ridden with it yet, but see how some people might like it. For me, I find some of the "auto shifting" of the front rings is cumbersome for when I would want to do a multi-shift of the rear cogs, if the mapped crossover point is reached during that multi-shift, the display beeps and shifting stops, requiring another poke at the levers to acknowledge/commence the front shift. I'll need to try it out on the road, but anticipate still preferring full manual control. Perhaps I'm just slow to adapt in this case, we'll see.

Turbotandem

Our builder at this point has done (2) tandems 2x11 Di2 XTR with drop levers and (2) 3x11. Spacing is working on all of them. On all of them the program adjustment (which can be done via e-tube software or on the handlebar display if you have one, are set at the full 16 steps inward. Here are a couple pictures of the latest 2x11 setup with compact cranks. This one is said to have about 1mm more clearance than my 3x11 setup on the same cranks.

Turbotandem

I have accessed the 16 point adjustment for FD position both by the on-bike display, and thru e-tube. Can't say where I found that. I am on the most current e-tube software which only runs on windows 10.

Actually nice or even essential that the multi-shift is blocked out by the "beep"; keeps you from making a ring shift before you want to, and prevents potential damage from cross chaining. Maybe you've chosen to put ring changes in the midst of the range rather than higher or lower. I've chosen to stay in a ring relatively wide range so the beep is near the cross chain point. Without synchro running you would have to make several more taps than the one you describe at the beep. That is, the multi-shift would presumably still stop because either di2 blocks out sever cross chain by default, or your the multi shift would progress and would break your chain (or over slacken and fall off). If the di2 default prevents the damaging shift, then your "manual" approach would need to tap the FD, and then backup on the RD to the target gear, and only then progress with your multi shifts.

twocicle

With manual shifting, I pretty much always hit both front/rear shifts at the same time or close to it, so that gear progressions match up and never crosschain. That is ingrained in my muscle memory and don't even think about it. I understand why synchro shifting prevents an otherwise unexpected front shift and instead interjects a beep, and then requires another tap on the shifter, but I'm not so sure that would be more or less efficient yet. TBD IRL OTR (on the road).

The laptop I had tried the latest software just a couple weeks ago is a Windows 7 64bit, so maybe it is not the very latest version you have on Windows 10. Just got new laptop with Win 10 Pro 64bit, so I'll take a look to compare functionality with each.

Turbotandem

I may have neglected to describe a brace I had made for the drive spider. One Lightning spider years ago broke on my tandem for a double ring so I am cautious. The triple spider looks pretty good but it also had an opportunity to stiffen in the space where the 9mm spacer washers go. So I had a 9mm thick ring made. 29 grams, large enough hole in the middle to clear the external bottom bracket (not pictured) and small enough outside diameter to clear the inner loop of the chain on a 22t chain ring. Pics attached.

Turbotandem

...and now that you have been on the road in real life, what did you determine? What is your impression?

Turbotandem

Based on direction from Twocicle's post https://www.bikeforums.net/19079472-post79.html and direct correspondence, I replicated the FD mount using problem solvers direct mount adapter and shimano direct mount arm per Twocicle. This achieved a FD mount 3mm closer to frame than stock, which solves the issue of using this XTR 3-speed FD on a road configuration. I took a few pictures of the process below.

Notes:
~ My friend Tasshi get the award for the most over use of giant equipment on the smallest 15 gram part. His home shop includes machines as big as an upright piano. He milled precisely 3mm off the mount
~ we chose to mill the full 3mm out of the mount groove rather than split the differnce by granding some of the fin off the leg. You could argue for that approach as Twocicle did. My choice was that the collar itself is +-3mm thick as it bands around the frame, so leaving +-3mm of material behind the groove was sufficient. The groove is also thru a much wider aspect of the collar.
~ Seen in pictures is also the 45 degree filing I did on the back of the shimano mount leg. This clears the frame by 0.5mm or so. Also note the mounting bolt for this leg was shortened not to run thru and damage frame
~ Note the arrow in finished picture indicating the next nearest part of the FD to the frame after the modification. I chose not to file anything on the FD itself, and with 3mm modification the FD body clear the frame by -0.5mm or less. You can sort of tell the proximity in the reflection, a sheet of paper fits between. The balance of the FD parts clear frame easily
~ note measurements from frame center to inside of FD cage in it's lowest position before and after. +-36mm before +_33mm after (if I held the gage just a little better to CL)

twocicle

So all said and done and paid Tasshi enough for a new Mercedes... did the 3mm offset reduction of the direct mount adapter(s) completely resolve the XTR usage issues on your road tandem?

Turbotandem

For the 10 minutes in Tasshi's shop, and insisting he take at least money to get the kids ice cream for his time; yes the 3mm reduction hits the mark for the gravel tandem with the "road" 68mm BB spacing. No more than 3mm is needed.

tandemracer

Maybe they read your post, but a cammed shim does now exist that would allow adjustment of the front derailleur reach:
https://www.sjscycles.co.uk/gear-spa...split/?geoc=US

twocicle

^^^ cool

"Designed for fitting a 34.9mm front mech on a 28.6mm frame allowing adjustment outside of the mech's normal range."

So it would only fit if the frame has a skinny seatpost to start with.