Options for lower gearing on tandem

[PacNW2Ford]

Originally Posted by deluz

Cranksets for tandems are really limited. The trend is to use 2X compact cranksets which would be 50/34. Also my wife likes 165mm cranks which are almost impossible to find. DaVinci and
Lightning are the only options I know of.
I was thinking the jumps on an 11-40 would be too big but looking at it not that much different than my current 12-32 10 speed cassette.

Pricey and currently out of stock, but Rene Herse makes sub compact tandem doubles with available 165mm arms. 26T small ring.

[cmbicycles]

If you are running Sram 10s road, you could use a Sram Mtb rear derailleur which should allow you to run a little bigger cassette than a 11-34. You just need to make sure the derailleur you choose works with your shifters. Of course switching to 11 or 12 speed would open up wider cassette range options, but I'm not sure what it would offer in terms of tandem cranks.

[oldpotatoe]

Originally Posted by deluz

My wife and I are at a combined age of 132 and climbing hills is getting tougher.
I can always just push harder to get up the hill but would be nice to have the option to go easier.
Current gearing is 50/39/28 on front and 12-32 on back 10 speed.

I came up with following option:

1. Change small chain ring to 26T. This would be cheap and easy and give a 7% reduction which might be enough. Currently shifting from 28 to 39 is not super smooth but not bad, not sure if 26 to 39 would be worse. When shifting from 39 to 26 would have to downshift the back first or it would be too big of a jump.
Maybe change the 39T to 38T.

2. Larger cassette. There is not a 12-34 so would have to go 11-34 which would be a 6.25% reduction.
Rear derailleur is SRAM Force rated for 32T so not sure it can work.

3. Change to 12 speed. I see two options here, Campy chorus or SRAM etap.
Chorus has max cassette of 34T, I believe etap can go to 36T.
Both of these would be quite expensive and not sure if it is feasible.
Will a 12 speed chain work on my current chainrings?
Can I run etap on just the rear and keep my mechanical shifting triple on front?
Seems like that would be possible if it works on 1X cranksets.
Getting rid of the rear shift cable is appealing although my current SRAM works very well.

Thanks for any input.

To shift the rear der of sram etap ya gotta have both shifters, even with 1by.

Not sure if the shift levers can 'see' the rear der on a tandem, with etap..not sure of the distances involved.

Not sure how you use a sram rear der, but have a triple...Do you have a shimano or Campag LH shifter?
No sram drop bar LH shifters are a triple. Pretty sure.

BUT, I'd get a 26 or even 24t small ring..do that first and see if it accomplished what you want by riding the bike. If not, then investigate a bigger cogset.

[lzuk]

You may want to check out the Co-Motion website and see what they offer on the newest latest and greatest. They know about tandem gearing.
Tandem gearing is a compromise. You probably don't want big jumps in the gearing. As a tandem team we all have a sweet spot in cadence so see if you can give up any of your gearing to gain on the cassette on the top or bottom end.
I think dropping to a 26 or 24 front ring saves your middle and big ring gearing but the shifting won't be any better to the small ring so beware.
We have a Ultegra 10 speed midcage derailleur and with a wolfstooth use cassettes from 11-28 thru 12-36 with no problems.

[deluz]

I am using an old Campy Centaur triple shifter on the front. It works pretty well and has lasted a long time.
I went ahead ordered a 12-36 cassette since it will give a lower gear than changing the front to a 26. I can always do that later if needed.
If it doesn't work I will add a RoadLink.
I did look at Comotion and they are using 50/34 compact cranks with 11-34 cassette, so the lowest gear is 34/34.
Also looked at Calfee and they are showing Ligtning cranks, would love some of those but it's $2,000 for a set.
Going to 11 speed only adds an 11T cog which I don't need. 12 speed would add one more gear.
Thanks to all who replied.

[sjbraun]

Our CoMotion came with Ultegra Di2, a 50-34 CoMotion branded (FSA) crank and an 11-40 cassette. The RD manages the wide range cassette without any difficulty, despite being rated to only a 34 tooth largest cog.

[BRad704]

Nevermind my idea.

[yinzerniner]

Originally Posted by BRad704

you can run up to a 42t cassette on the Sram Force 3.0 Medium cage, and it's still 'Exact Actuation' so should work with the shifters already on the bike.

Swap RD for the Force 3.0 version.
Get 11-40(or so) cassette.
New longer Chain.

If it's the Force x1 cage it's exact actuation, but the RD and cage design is for 1x operation only - won't shift correctly with a front derailleur.

Pic and source for clarity:
https://bicycles.stackexchange.com/q...ur/24681#24681

[BRad704]

Originally Posted by yinzerniner

If it's the Force x1 cage it's exact actuation, but the RD and cage design is for 1x operation only - won't shift correctly with a front derailleur.

Pic and source for clarity:
https://bicycles.stackexchange.com/q...ur/24681#24681

Well crap. You're right. I'll update my post to avoid spreading bad info.

[deluz]

I decided to order the 12-36 cassette which I now have.
There could be a problem with chain wrap capacity though.
I figured going from a 34T to 36T adds about 1 inch of chain length so I am going to add a link to the chain. I might be able to not do that but afraid in the big - big combo its going to be really stretched although its a gear I would not normally use but could accidentally shift into it. On a tandem its harder to keep track which gear you are in.
This could result in the chain being too loose when on the 28T chainring.
But we only use the maybe the top 4 cogs in that case.
Looking at the current setup it looks like it might work.
I will know later today after I install it.

[binouye]

Originally Posted by deluz

I did look at Comotion and they are using 50/34 compact cranks with 11-34 cassette, so the lowest gear is 34/34.

On our newer Co-motion tandem we got an FSA 48/32 compact crank, which I paired with an 11-34 Ultegra 11spd cassette (and long cage Athena 11spd RD). Not much lower, but a little bit lower than 1:1. Its been sufficient so far. Shifting the subcompact rings in front is better than the 52/42/30 on our other tandem, but gives up some range.

[Dave]

It takes 4 teeth to use up an inch, but any extra teeth requires checking the length. The chain length formula at parktool.com will tell you how much extra you might have.

[deluz]

Originally Posted by Dave

It takes 4 teeth to use up an inch, but any extra teeth requires checking the length. The chain length formula at parktool.com will tell you how much extra you might have.

Oops I meant to say 32T to 36T.

[Ralph]

Nothing wrong with adding enough chain to make big to big work, and running the small front to "smaller" cogs a little slack. Don't use them anyway, and it may help keeping the RD upper pulley off the big rear cog.

[deluz]

I ended up putting on a 12-36 cassette.
It shifts into the 36T but there is barely enough space for the chain between the 36T cog and jockey wheel and the RD is angled behind rear wheel.
Had to adjust the B-screw way in.
I decided to try a Roadlink and installed it today. I think it puts the RD into better position. Took it for a short test ride and it seems to be shifting good.
Looking forward to trying this out on a real ride.