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Chainset advice

MR EDWARD THOMPSON2023-04-14 18:13:55

Hi, I'm currently building a tandem frame out of Bamboo - it's from a kit supplied by Bamboo Bicycle Club. I've built a bamboo road bike before from one of their kits  and did LEJOG on it - I love it. The frame is nearly complete so there's no going back!

 I plan on using it to do Euro Velo Route from Roscoff to Santander.with my wife.  I wont be going fast and probably only doing 40 miles a day. Just pootling about and it's not a hugely hilly route. We'll be doing some cycle camping. 

Can anyone recommend a gearing set up? I will explain:

I'll be setting up the chainset and sync chain all on the same side (apparently that avoids stress on the frame - something I'm keen to avoid for obvious reasons).

I'll be repurposing an existing 700c Gravel bike with  a cassette of 12-32t. The chainring is a triple but I plan on using the outer one as the sync drive (so, that will leave me with two usable rear chainrings that can drive the cassette).

Does anyone have any thoughts on a good chainring/ drive train combination?

I'm thinking of a 32t drive/sync train, and two cassettes of say 34t and 24t. But don't know if that would be rubbish or not.  Any thoughts gratefully received. Many thanks 

Apparently, I could swap the cassette for one that goes up to 34t (that's the max size the gears can accommodate). But I'm not convinced it's worth it.








Edmund Dunstan2023-04-15 11:36:39
Sounds like an interesting project. If you're using the outer ring of the triple for the timing chain/sync drive, you may need a longer front axle if it's to run in line, but the chainring only has to match the existing outer unless you really want to change it (and larger chainwheels wear less). If I understand correctly, using a middle chainring of 34T would give you a top gear of 34 x 27/12 = 76.5" - fairly low and may not enable you to take advantage of a tandem's speed on the flat, while the bottom would be 24 x 27/32 = 20.25" -  a bit higher than may of us would use but OK if not many steep hills, but a 34T bottom sprocket might be better. Is the cassette new enough to be worth reusing?  At the front, what you can do depends on the capacity of the mech, which has always seemed a dark art to me.
Hope these thoughts help.
MR EDWARD THOMPSON2023-04-15 14:38:27

Many thanks Edmund - that's really useful. So, if I understand correctly, it doesn't matter what size the chainrings are on the sync chain (but both need to be the same size (obviously) and the smaller they are the quicker they will wear out).

Armed with that info, I will get a bigger rear cassette (upgrade the 12-32t to a 12-34t).

You've helped reduce my query down to one set of variables ;any thoughts on the size of the two chainrings (i.e the ones that'll drive the rear cassette) gratefully received.