Options for closer gear spacing

[deluz]

On our tandem I have 10 speed with 50/39/28 front and 12/32 rear.
I am comfortable with cadence in the 90-100 range but my wife likes 80-90.
We are old, don’t race or put out that much power so top speed is not that important. I have noticed because of the large gear jumps when we are pedaling faster than 90rpm and then I shift down it goes to 80rpm. Also when we stand it helps to be in the perfect gear. I am not seeing any options for closer gearing on a 10 speed cassette so considering 11 speed and changing the shifter from SRAM Red to Force 22. I am assuming an 11 speed chain would work on our current 10 speed crankset. With 11 speed I could use a 14/28 cassette which we would spin out on downhills but I am not too worried about. There is also a 12/28 but only available in Dura Ace which is pricey. Any other ideas?

[PortlyPuncheur]

Have you considered a smaller crankset? A 10 speed mtb crankset will often go down to 22t and could let you spend more time in the smaller end of the cassette where the single tooth jumps live.

[PortlyPuncheur]

Other thoughts:
Perhaps you could switch your wife to shorter crankarms? Shorter arms typically encourage faster cadences, from what I've read, and it meshes with my experience. I switched from 170mm to 160mm and my preferred cadence probably increased from 85 to 95.

I agree, you shouldn't have any trouble running 11 speed chains on 10 speed chainrings. My experience doing so has mostly been limited to 2x setups, but I've also setup some older triples (probably designed with for 7 or 8 speed) with 10 speed chains without issues.

[deluz]

Originally Posted by PortlyPuncheur

Have you considered a smaller crankset? A 10 speed mtb crankset will often go down to 22t and could let you spend more time in the smaller end of the cassette where the single tooth jumps live.

I wish there was such a thing as a compact triple tandem crankset but I could not find one. I think Lightning might be able to make such a thing but they are awfully expensive.

Another option I found is Miche makes some 10 speed cassettes in various ratios. They have a 13-30 that would be good. I tried one of their 11 speed cassettes once and it did not go well and they don't get very good reviews but being 10 speed it might be more likely to work and it is by far the cheapest option as I don't have to change any thing else.

[robt57]

Juniors cassette? I have a 14-28 in use still [11s]

BTW, with 10s you can use an 11 speed chain and cassette, just trim toward the top or bottom ratio cog as you will only get the 10 the shifter allows for.

80 RPM mashing with 2 motors, when did you measure that chain last anyway.

[Mark McM]

Gearing selection will always be a trade-off between total range and size steps between gears. So you'll probably have to start with the total range you want (or can live with). As far as 10spd cassettes with smaller jumps, there are plenty available - but they won't have the same range. The only way to get the same range with smaller jumps is to add sprockets.

As far as the comment about using smaller chainrings to move to the smaller end of the cassette - that doesn't always result in smaller gear jumps. For example, a jump from a 12 to an 11 (9.1%) is larger than the jump from a 25 to a 23 (8.7%), even though the former is 1 tooth jump and the later is 2 teeth). And very wide range cassettes may have 2 tooth jumps at the small end of the cassette, which can be quite large as a percentage (for example, the jump from a 15 to a 13 is 15.3%). SRAM likes to claim that their AXS cassettes have more 1 tooth jumps then their competitors. But since these cassettes start with a very small sprocket the average percentage between gear sizes is actually larger on AXS cassettes.

[Mark McM]

Originally Posted by deluz

I wish there was such a thing as a compact triple tandem crankset but I could not find one. I think Lightning might be able to make such a thing but they are awfully expensive.

But aren't the triple chainrings on the stoker's right crank, which is basically a standard crankarm? Couldn't you substitute a right triple crank for the stoker's left crankarm? The crankarms would be a bit mismatched, but that would be mostly a cosmetic thing.

[PortlyPuncheur]

I'm pretty ignorant about tandems I guess. Maybe it's time to correct that. Latest excuse for N+1 identified. Or would this be N+2?

[deluz]

Originally Posted by Mark McM

But aren't the triple chainrings on the stoker's right crank, which is basically a standard crankarm? Couldn't you substitute a right triple crank for the stoker's left crankarm? The crankarms would be a bit mismatched, but that would be mostly a cosmetic thing.

Not sure if this would work or not. It is a FSA Gossamer tandem crankset so I would have to find a crankset that is compatible with the left side crankarm that has the timing ring on it.

I think DaVinci has something that would work but I would have go back to using a square taper BB.

Stoker is already using a shorter crank arm at 165mm.

I am a little worried about using an 11 speed chain on the 28T ring, it would be an experiment.

[PortlyPuncheur]

This may or may not be of interest. TLDR - he recommends radically shortened stoker cranks and links to some of his favored options. I thought about getting him to shorten some cranks for my mother at one point.

https://bikesmithdesign.com/Short_Cranks/tandem.html

[Mark McM]

Originally Posted by deluz

Not sure if this would work or not. It is a FSA Gossamer tandem crankset so I would have to find a crankset that is compatible with the left side crankarm that has the timing ring on it.

I think DaVinci has something that would work but I would have go back to using a square taper BB.

Stoker is already using a shorter crank arm at 165mm.

I am a little worried about using an 11 speed chain on the 28T ring, it would be an experiment.

Compact triple tandem cranksets were not uncommon back in the days of square taper spindles, so you could look on the vintage market for them. Since the same BCD (110mm/74mm) was used into the 11spd era, you should be able to find compatible chainrings.

Here's another square taper option:

https://www.renehersecycles.com/shop...-triple-crank/

[owly]

Was an expensive route, but I put together a 10sp 12-28 custom, using three Ultegra cassette cogs/clusters: 12,14,15,16,17,18,19,21,24,28.

Chose that mix as I have a 40t large ring and tend to sit in the 16 or 17t depending on tyre fitted. Was chasing a good spread of 1tooth jumps either side of that (favoring the lower side).

When carrying a load I change the three biggest cogs and end up with a 30t.

May be able to do similar with cheaper 105.

[deluz]

I went ahead and ordered the Miche Primato 13-30 cassette from ProBikekit.
As long as it shifts ok I think it will provide the gearing I am looking for.

[Gabe77]

I don't understand the logic of how changing cassette gearing will solve this problem - since the issue of differing preferred cadences will still exist in all gears... Its like solving the problem of a loud upstairs neighbour by both residents moving up one floor.
Apart from varying crank lengths - which has been suggested - the other traditional way of mediating differing pedalling styles in tandem partnerships has been advancing the crank position a few teeth. That way the other rider has a maximum point of effort at a slightly different moment - and its the easiest option to try. Applied with the crank length trick this may push both of you toward a middle.
A Sheldon Brown ghost suggestion would be moving to a BioPace crankset or some other variant of ovoid cranks.

[Mikemelbrooks]

I wonder if anyone has tried using different sized chainrings on the crossover drive. If you could put up with the pedal stokes going in and out phase It might work?