Electronic & Hydraulic Shifting (Di2, Ui2, customisations)

There's exactly one Di2 triple FD. It's discontinued and extremely rare. Official max chainring is 40t and you'll need to use it with an MTB RD. No problem using it with road shifters though.

Yeah, I probably won't be moving to a triple. :)

I would consider putting a 28T on my 1x MTB and a 46T cassette on the gravel bikes but for now I think I'll keep the 2x (11-42T).

If anyone knows where to get the lowest three cogs on a Shimano MTB cassette as a spare part

Download the EV PDF, make a note of the part number, order from any LBS who deals with Madison, discover that the cost is more than a whole cassette🙂

Maybe. Ideally, I'd like to find someone who's trashed a middle cog that's replacing a whole cassette for the same reason and then piece together a working one.

Reduce. Reuse. Recycle.

No one can be bothered with half-step triples and shit in a race situation (TTs excepted perhaps)

TT is the market I envision driving eventual adoption of my idea. But the whole concept is predicated on being electronically shifted, where hopefully the bother disappears altogether.

It could be two separate shifting modes where if it doesn't half step it just minimises front shifts, or long-press to skip the half-step or vice versa.

Because there's only 2t difference in the big rings, it should be possible to make shifts between them almost as smooth as rear shifts, in two ways. First, since they're almost the same size they can be right next to each other, like cassette cogs. I verified this by putting all these rings on a crank with the aid of a 130/110 38t. Second, the 2t gap means it lines up every 180 degrees. With a bit of CAD shift magic, and perhaps a crank position sensor to time the shifts, I bet they could be super snappy and efficient.

The TT folks would love it, I bet. And surely the roadies could see the benefit when it comes to taking a pull on the front of a pack.

The TT folks would love it

If you're thinking UK, I'm not sure. First, on an ideal combination of course and conditions, one gear is enough. Certainly one ring has been enough for as long as I've been in the game. The jumps even as far as the 13-12 shift are well within the operating range of the rider, to the extent that inserting a mid-point into that 8% change is way more complexity than it's worth given the miniscule opportunity for improving biomechanical efficiency.

I guess my pissweak legs and lazy respiration makes me overly sensitive to cadence...

But hey, ceramic bearings are a thing, so marginal gains here we come. It's just a matter of whether there's enough years left in capitalism.

marginal gains

But it's not a gain. Just the aero drag from adding a FD is going to lose more than being 3rpm away from your "optimal" cadence, e.g. let's take one of the fast men who wants to be at 90rpm:
58/12 at 90rpm = 34.5mph
inclination changes from -1% to +1%
58/12 at 86rpm = 33mph
down-shift to avoid bogging
58/13 at 93rpm = 33mph

Your half-step offers
56/12 at 89rpm = 33mph

but who is that sensitive to cadence? Pursuit riders maybe🙂

Hang on, if you look at my graph of gear number versus ratio, you can see that all I'm doing is making the average step about the same as 19 to 18.

If that's a jump worth having at lower speed, surely there's a use for it at higher speed, no?

I mean, ideally you'd have a CVT that didn't add drag and weigh a ton, but since this provides what you say is more gears than you need for a mere 50g of extra chainring, what's not to like? The gears are there if you want them, otherwise a no-brainer to skip.

Also, imagine the system knew where not only cranks were in the rotation, but cassette too, and delayed shifts to the perfect moment for a seamless shift.

If every shift was so perfect the chain never jumped, you could maybe even have it shift for you, and just tell it how hard you want to go.

Someone jailbreak Di2!

Someone jailbreak Di2!

As if the official software doesn't crash enough...

If that's a jump worth having at lower speed, surely there's a use for it at higher speed, no?

My point being that the 18/19 jump isn't worth having, but 18/20 is worse than 12/13 so we're stuck with it on drives which work well within the load and packaging requirements of a bicycle.
⅜" pitch chain would work, and apparently was used by Team GB on the track last time around, so you could switch the cassette from today's typical close ratio TT set of 11-23 to a 15-30 to get nicer chordal action and smaller ratio jumps at the top end. That would be much better from every aspect than a half-step, if you still think the 11/12 shift is too big.

a mere 50g of extra chainring

It's not just 50g of chainring on a TT bike, it's changing from a clean 1× drive to a 2× with all the drag penalty of a FD and second ring

Sure, a 3/8" or 10mm pitch would nearly fix it completely. Although it's an interesting question whether it would be possible to make such a chain that shifts and/or lasts as well... I used to wonder about that a lot.

shifts and/or lasts

More of one usually means less of the other🙂

I verified this

And eight and a half years ago you said

Mark my words - this will come to pass as standard stuff...Keep an eye on pro time trial rigs and tri bikes over the next few years... probably sooner

How's that going? 1×12 is found anywhere there isn't a mountain to climb (and in some places where there is), half-step 3×10 is found only in the dustbin of history 😉

I'm pretty sure they'll have to come up with a different way to milk us for cash than just adding another cog... That's been getting silly lately.

But as you say, given the aero penalty of an FD, I guess the next compatibility breaking drivetrain change to chase marginal gains and force upgrades is way more likely to be a reduction in chain pitch...

My dad's Di2 needs to be stored for 2-3 years until his eponymous grandson grows into it. What's my battery management strategy?

Sell battery, buy new one in 2-3 years?

Sell battery

Is anybody going to want a 6 year old BTR1, however lightly used?

buy new one in 2-3 years?

As a corollary to the above, will I still be able to buy an external battery in 2026? I just want the bike rideable for a year as is, then he can make his own decision about rewiring for an internal battery without dragging me into the project 🙂

If rewiring for internal is on the table, then changing the cells to brand new ones shouldnt be an issue either :)

On a serious note, if I had to deal with this, I’d probably setup reminders to put it on charge periodically, and not let it fully discharge. Or buy one of those wifi programmable plugs, write code for it to automatically switch on for 2 hours every 3 months and plug it in behind your telly and not look at it for the next 3 years. Might be overkill :D

I'd have guessed at quarterly maintenance.

Obviously if the boy decides to go internal, he can easily buy a new battery

From what I know of lipo batteries, they don't really like to be fully charged or fully flat; they're best stored with a half charge.

Interesting question whether 2-3 years is long enough for it to go dead... I'm pretty sure enough of a half charge would still be there after a year, so maybe check it then?

Of course, this might be moot, I haven't actually checked the battery yet. Father's last race was 2020, I think he charged it at the beginning of 2021 just in case but it may not have been touched since.

Didn't have these worries about taking over his 1949 bike 🙂

Well there you go, you can see what effect a couple of years have had before you even start.

My etap shift batteries went flat at a road race once, ensuing much hilarity amongst the old boys in the school hall

Can you plug that battery in e-tube? I think it's possible but I don't have any to check, and maybe an older version of the hardware is needed