Miitch's Time-Trial-Tandem

And here is tandem number 2

This is how it is currently sat in the shed at my parents house, there is the chance of some light touring this summer so it will definitely get dusted off for then.
Last time I rode this properly was a 36 hour 450km round strip from Aarhus in Denmark to Flensburg in Germany and back

Well one way is not having reversed pedal threads?

Tandem 2 has normal threads and a cross over, that's why I was confused

Presumably they're tandem-specific cranks, rather than adapted solo ones.

This is all new to me, so a quick search led to me to Sheldon (obvs) who explains the merits of crossover and single-sided drives well enough for even me to understand.

Sorry for the naivety but why is straight through better?

Sheldon's reasons as linked by @Scilly.Suffolk are correct, let me know if you want them explained, or think about it for yourself in terms of which way the chains are trying to pull the BB shells out of alignment and how the drive torque gets from the pilot's cranks to the wheel.

So, how about a fixed tandem two-up? Potentially the most niche cycle race ever?

You definitely should... Pete regularly races fixed too so he'd be keen to see it happen.

It does also mean matchy matchy bars

I picked a second set of Mavic Bars up from @Ecunard and so looks like we are going matchy matchy...

This project had been set aside for a bit while the rest of life happened, but I do now have some more bits.
Need to drill the fork to accommodate a (new style) recessed brake bolt
And to source a 60T 1/8th 130BCD chainring and a left hand crank (to make it single sided drive)

Also I need to get rid of that awful yellow tape, time for something a bit more subtle I think...

SO GOOD.

Started having a fiddle with this tonight and made a tiny bit of headway...

I have taken the front chain-set off and flipped it over - both bolts were very loose which is worrying.
I measured the BB and both sides had 15mm showing so I didn't flip the BB axle over too. (I hope this is ok). Amazingly, almost 50 years after it was originally fitted the BB is still running smooth and free.
Problems:
My crank puller doesn't fit the TA crank.
I have no idea about how to go about drilling the rear to accommodate a modern caliper.
I don't know if it's safe to drill the forks.
The bolt that holds my seatpost is imperial.

In conclusion,
I have a lot of issues...

My crank puller doesn't fit the TA crank.

There is a thread (perhaps in "open toolbox") where people passed the appropriate puller around, failing which I think SJS stock them.

I have no idea about how to go about drilling the rear to accommodate a modern caliper.

I can't see the bridge clearly but even if there is enough reinforcement to allow the hole to be drilled, the chance of you accurately enlarging the hole with a flexible drive is vanishingly small.

Scroll down to "Mounting recessed-mounting calipers on older frames" on this page, if you don't fancy getting a new bridge installed.

I don't know if it's safe to drill the forks.

Yes, but without a drill press it's inadvisable for the same reasons as the rear.

Sounds like a right angled drill might be an ok way of doing the rear then...
It is currently spaced to 130mm - I have vague distant plans of maybe getting all the mounts and stuff chopped off and it respaced to 120mm and maybe also painted.
So if I did make a catastrophic mess, it would be all the more reason to get that done.

I do have access to a drill press, so might use that to carefully do the front - I work in a bike shop and have done this before on customers bikes - my question was more about the sensibilities of doing it on a tandem fork crown.

Open tool box - Thanks for all the knowledge!

Sounds like a right angled drill might be an ok way of doing the rear then...

Not really.

It's easy enough to drill forks off-centre/at an angle when you have unhindered access, never mind doing it with a right-angled drill within the confines of the rear triangle.

Even if you cut a bit down, I think you'd find the drill would be fouled by the seat tube.

What does the bridge look like? Drill the back and mount the brake inside the triangle, ie backwards?

I have no idea about how to go about drilling the rear to accommodate a modern caliper

You don't need to, the centre bolt on a front caliper will be long enough to allow you to fit a hex nut.
https://www.lfgss.com/conversations/226321/?offset=125#10056988

Don't know why I didn't think of this earlier!
Anyone wanna swap a black 105 rear caliper for a front?

Anyone wanna swap a black 105 rear caliper for a front?

If you get a long enough tube nut, you can probably use the rear caliper on the front

It's even on clearance!
http://www.chainreactioncycles.com/shimano-caliper-brake-sunken-nut/rp-prod17557

Again...

Don't know why I didn't think of this earlier!

Don't know why I didn't think of this earlier!

[cough]

Scroll down to "Mounting recessed-mounting calipers on older frames" on this page, if you don't fancy getting a new bridge installed.

It's even on clearance!

18mm might not be long enough, but Shimano go up to 32mm

The 5600 brakes on mine came retail packed with all the tube nuts, so I have spare 18mm and 27mm

@edmundro kindly lent to me a TA Crank Puller so I managed to remove the TA cranks.
So I managed to get this far:

So now I need a 175mm left hand DA crank and a big chainring - I'm thinking of going to 60T.

Also just for reference this is the back brake bridge, which I think I'll leave undrilled and just run with a front 105 brake.

Then this is the front:

Which I'll take apart and decide if I'm going to drill or not.

Thanks to @mdcc_tester I've managed to get a 55T ring mounted on.

But I have an issue... I have chain overlap - as it's turning the two chains rub against one another.

I've flipped both rings to they're mounted the "wrong way" but can't find a sweet spot where nothing catches - how stupid would using washers to space the outside ring be? Considering there is the power of two people going through there, I feel like it's quite a stupid idea. But it's the only idea I've had so far...

geared chain?

Good point, probably better to do the timing chain right?

Think tester will confirm but I'm sure 3/32 is fine for track use and 1/8 is unnecessary. Would only changing the timing chain give you enough room?

I use 10-speed dérailleur chain for the timing chain and spacers to move the timing rings inboard by 2mm, because the 1R8 final drive chain has very long pins. There's probably room for 8-speed, which would be a bit stronger, but 10 is what I had laying around and it only has to take my power.