Bill Kapaun

Exactly what's the weight difference?
Ignore List.

bwilli88 

Better setup would be a Sturmey Archer 3 speed with 2 cogs.

JISO

Looks like the closest alternative would be 50/26T front with a 16/19 dual freewheel cog and a 27T cog on the other side of the hub with a tensioner

This would be 83 gear inches top gear and 43 low gear on 16T with the ability to switch manually to 19T for 36 to 70 gear inches. 27T cog would be cumbersome to set up but results in a 25 to 50 inches two-speed range

MarcusT

A colleague had a folding Brompton with a similar set up. On a long ride, the chain tensioner fell off and we could not find the pieces. It was ride-able but very frustrating. I don't believe your set up would be any more reliable or have less drag than a regular derailleur.

bwilli88 

Here is my simple alternative to this. A dingle speed.
It has both a 17-21 fixed cog and freewheel on the flip flop hub. The chainrings are 46x42.
This gives me 2 very usable gears with the same length chain. the 21-42 is 55gi and the 17-46 is 75gi. Not the ratios you are looking for but much simpler setup.

JISO

Yeah I looked for the 17/21 Surly cogs but they are out of production. White Industries are the only ones making something similar

JISO

Too aggressive to attempt to tour on this but will test drive it locally. Thanks

oldbobcat

I'd like to see the front derailleur that can make a 24t jump with nothing in the middle.

JISO

That too, hopefully it's not battery operated

70sSanO

I think at this point you have kind of pushed this a bit too far.

You started out with a triple crank and 2 cogs, but having to stop to move the chain was a problem.

Everyone ran around with suggestions and now you’re contemplating a double crank with 2 cogs that you have to stop to move the chain thus making a full 360 but with one less chainring on your Biopace crank. Why would you even do that?

I get the impression this light touring bike may only exist in your head.

But if I’m wrong, just run your original 3x2 as I doubt there is any other solution to meet your wants.

John

wheelreason

Why?

70sSanO

I believe the OP has mistakenly put too much emphasis on drivetrain friction and optimum working chainline. Modern bushingless chains are much more flexible.

There is some merit of running fewer cogs and friction shifting. Those who are not interested in optimum performance and can live with larger gaps can ride along however they want.

He is also under the impression that a no dish wheel will be much more durable. While technically true, a poorly made no dish wheel will not hold up as well as a properly made dished wheel. But running fewer cogs and keeping to 126mm OLD or less should be more than durable. Even more so for light touring and modern rims.

I could see a vintage gearing setup of a 3x5 with the 26-38-50 and a 13-16-20-26-34, or there abouts. This more than covers his gear inches and lets him ride in the 38t the majority of the time.

John

JISO

Of course it's in my head. I'm designing and sourcing parts for it right now. What kind of comment is that?

I appreciate the suggestions but apparently I'm okay with moving the chain manually.

If a symmetric wheel is stronger I can run it with fewer spokes and reduce drag. What's with the grump sauce

70sSanO

Sorry I didn't explain myself. It is a theoretical bike, not an actual bike.

No one would look at fewer spokes on a touring bike to reduce drag a nearly immeasurable amount while there is enormous aerodynamic drag from the panniers. It makes no sense in the real world.

John

JISO

Exactly, that's why this one has triathlon aero bars instead of panniers. Great minds think alike

squirtdad

that is basically silly

drag for the wheel for touring is not a factor even without panniers or what ever you are carrying.

peopled have toured all over the world with standard asymmetrical spoke set ups
more spokes is better in a lot of ways, like if you break on a low spoke count wheel you have wheel that will be unrideable fast, but you can get away with a broken spoke on a 32 or 36 spoke count wheel

Over all very little of your design ideas seem based in practicality or reality of touring, especially in an sort of hils

good luck but don't be surprised with a little grumpus on focus on non issues vs real world

JISO

Sure, and if you're riding on a dished wheel you need more spokes cause they break quicker, so who's right?

squirtdad

as a lawyer would say: facts not in evidence

Show where properly built wheel ( even tensions, double buttted stainless spokes, 3 cross, on good quality rims) breaks spokes frequently. I am a big guy and have thousands of mile on builds like that with out a broken spoke

your theory is not supported by any evidence

70sSanO

I'm hoping I'm not included in that group.

John

JISO

Pretty hilarious I need to submit evidence to "prove" that more dish = more spokes = more drag

JISO

Classy

phughes

Me too. I have thousands of miles on my Surly LHT, carrying a lot of weight, no broken spokes, and they are still true. I did have them detensioned and retensioned by hand when I bought the bike. That is something I always do to a new machine built rim.

The rims have been bullet proof.