DeadGrandpa

I have a recumbent trike with Shimano e-assist and a Deore RD-T6000 long cage on a 11-36 ten speed cassette. The original front chain ring was 44T, which was fine for general flatland and some rolling hills. Before going to the Adirondacks for a bike tour, I put on a 38T front chain ring (and a new Shimano chain), which helped on the more challenging climbs. Even though I have a motor, I only use the lowest level of assist and I was pedaling pretty hard on every climb. I even broke a chain (which I had never done before). I had the tools to make the repairs, but I concluded I need an even lower gear for the steepest hills. Also, since returning home, I discovered that the chains recommended for e-assist bikes (particularly those with a mid drive motor) are built stronger than the standard chains. So I'm getting new chains, but I still think slightly lower gearing would help.

My derailleur is rated to work with the 11-36 cassette (according to the Shimano website), but I heard those specs are generally conservative. Does anyone know if my derailleur would handle an 11-40 or preferably an 11-42 cassette? Should I order a Wolf Tooth derailleur link when I order the cassette?

I'm sure I can get by without the upgrade, but I'm trying to do the bulk of the pedaling effort myself. I've never changed a cassette before, but I have the tools. I would hate to buy a new cassette if it won't work with the derailleur I have. My dealer is hours away, so this will be a DIY job, just me and YouTube. I do understand what the "B" screw does. Thanks for all advice, even if it's just keep what I've already got and leave well enough alone.

Bill Kapaun

The "conservative" part comes because there is a range of RDER hangar geometry + other factors that might enter the mix between different installations.
One bike might, one bike might not.
What's the smallest ring you can run to give you a high enough gear with an 11T cog? Can you stop at that speed, having a trike?

With that RDER, you could run a 22-32-44 triple and your current cassette.
Here's the listed spec's
https://bike.shimano.com/en-EU/produ...T6000-SGS.html

Iride01 

If you don't have the parts already and can try them out, then it'd be safer just to stay in specification. As Bill Kapaun said, if you go to a 3x front you can get much lower gearing than you can get with a 2x front and still have the high gearing too.

Spec's are conservative because everything about your particular bike will make a difference compared to someone else that got away with it.

And whether or not you are using your own power or the motors power, you still get much of your cardio-vascular benefit from your legs just going up and down.

DeadGrandpa

Since my trike was OEM designed and built with the Shimano Steps e8000 motor and a single front chain ring, 44T, going to a triple front crank set is not an option. With the change of the front chain ring to 38T, I have a lower gear range than before. Back on flatland, I can cruise at 15-17 if I want, but mostly average 12-14 to keep up on long rides with my partner. We generally push it to 16-18 for the final few miles, even with the 38T, going home. The change from 44T to 38T dropped my top gear from 103 to 89 gear inches, but I don't miss the top end. The low gear dropped from 31.5 to 27.2 gear inches, which helped some. The 42 cog on the bigger cassette would give me a low gear close to 23 gear inches with the 38T chain ring, which is where I liked to be (or even lower) when climbing with my unassisted two wheel bike, before I converted to three wheels.

Going downhill is where gravity puts on the speed, but I don't pedal much above 20 mph. On a few long hills, I've hit 35+ riding the brakes intermittently, but I don't like speeding much on unfamiliar roads. Avid BB-7 brakes do well for slowing down and stopping. Frankly, I have always preferred climbing hills over bombing downhill at motor vehicle speed.

grumpus

There are 34t rings for that motor, I wonder if you could pair that with a 44t for a useful double (even if you did have to shift by hand). Or there may just not be room.

tFUnK

I've gone 32t on a RD rated for 28t max, but that's not the same as going from 36t to 40t. That said, if running 1x, an extender like the WT should get it to clear the large cog, and since it's 1x you won't run into chain wrap capacity issues. I do this with a RD rated for 32t and run an extender to clear my 40t cassette.

maddog34

get the der dropper.

DeadGrandpa

That's exactly the kind of information I needed. Thanks very much. If you made the jump from 32 to 40 with a WT device, I believe I can go from 36 to 42 with a similar gizmo. I'd be satisfied with 11-40, but Shimano seems to skip the 40 in 10 speed, leaving the next choice to be 42 or 46, if I go with the Shimano brand, which I prefer.

tFUnK

Happy to help. Your RD (according to Google at least) has a wrap capacity of 47t so you can run 11-58t (assuming 1x) and still be ok 🤣 I used a generic extender on a RD rated for 36t big cog and it clears a 50t big cog.

cpach

You can extend range with an adapter, but the shifting does start to suffer the farther from spec you go, even if it does work. Given that you're touring on it, I'd recommend you just upgrade the whole derailleur. If you want, RD-M5120-SGS is officially compatible with up to a 46t cog and has a clutch to reduce chain drops, and would be otherwise compatible with everything else in your drivetrain, and at $40, isn't a lot more expensive than an adapter anyways.

You could also eke out more durability switching to a linkglide based drivetrain (Shimano CUES, etc) which basically uses 11 speed chains (regardless of the number of cogs in the back) with a modified shift gate pattern that is supposed to be considerably more durable than hyperglide, but you'd need to pair the new derailleur and cassette with a new shifter as well.

Crankycrank

Here is an exhaustive list of derailleurs you can compare specs with if you decide to buy a new one. Bicycle Cassettes & Drivetrains - Google Sheets

DeadGrandpa

I had just about decided that I needed a new derailleur to go with a larger cassette, and then I looked at the Linkglide system, which requires a new chain and shifter, as well. But I had just received my order for a set of KMC 10e chains, which don't appear to fit the Linkglide cassette teeth, which are thicker. A Linkglide chain will run on a standard cassette, but not the reverse.

So I think I'll just keep what I have for now, and by the time I wear out the KMC chains, I should be ready to go Linkglide system on everything. I'm not sure that the Linkglide trigger type shifter will work on my vertical hand grip (currently with a Microshift bar end shifter), but that problem is another few thousand miles in the future.