Hi
My wife and I ride a 90s Mercian tandem. We love it but, as it's a racing tandem, the stokers cockpit is rather on the short end and it can only fit caliper brakes. For unloaded day road riding this is not an issue but for loaded touring (Burley trailer out back) it has been a problem, especially on descents where the brakes just don't provide enough power.
... plus I wanted to buy a new bike and the tandem budget was the easiest to get approved
so, I've just ordered a new tandem frame / fork from Ritchey
This leads to some novel componentry dilemmas for me. the Mercian has downtube shifters, which I run friction with a 9sp mountain cassette and a 30/40/50 triple (old TA specialities) but ofc the new frame needs more modern shifters. final gear spread is 25-127" and does what we need it to, both on the flat and in the hills except the odd steep climb with the trailer loaded
The new tandem will be drop bar for the captain so I'm looking at drivetrain options, most available tandem chainsets seem to be triple but triple drop bar shifters are not easily available, which makes some sense considering the range you get from compact double these days. Plus the chainset ...erm... sets are OMGWTF expensive and nice really wide cassettes available these days
So I was wondering about the following, I know it sounds like a bodge but bear with me
- Set of SRAM force CX1 shifters (left is just a brake lever, right is SRAM 11sp)
- a wide ratio 11sp rear cassette (11-46 for preference)
- SRAM MTB rear derailleur
....So far I am confident that this is all compatible (except the capacity of the RD, which might only be 42T) Now the screwy part...
- compact 2 ring cranksets front and rear (probably 50/34 but there are options). No special tandem cranks
- Run the timing chain between the 2 smaller rings when unloaded on the road and between the two larger rings when offroad/ proper hills. I reckon it'd be less than a 10 minute job to swap the timing chain and drive chains over
this means running effectively 1x11 with 2 configurations. the spread in the high configuration would be 30-127" and in the low configuration 21-87". It would be a lot cheaper to build than a trad tandem set up, would lack a front derralieur and parts would be easily available as none of it is tandem specific. However, I can see the possible issues
- just daft, both chains on the same side, are you MAD?
- possibly the worst of both worlds, will always be lacking the gears I want when we want them
- faff to change the timing chain over, especially during a ride. need to carry a short length of chain to make the difference
- Potentially miss one gear on the extreme in each configuration to crosschaining
Is this just a daft idea?
or there are compact double options that I'm missing? I think Middleburn should be able to do it as an option but with the above idea I could do the whole drivetrain (incl carbon cranks, when on special) for about the same cost as the middleburn crankset(s)