10-50 cassette

[Tigerbiten]

Sheldon Brown's gear calc will work with the SA gears as you can pick 3 chainrings, various sprockets and a hub gear at the same time.
What it doesn't work with is twin hub gears/quad chainrings and a hub gear like my setup.
I need to divide my sprocket by 2.5 to get all my 56 gears (2x2x14) to show up.

I've found I work less hard downhill now I have +130" gears.
When I topped out at 100", I used to overspin (+100 rpm) to try and get over 30 mph before starting to freewheel.
And I found I was hitting around that speed on roughly 5% hills which are fairly common.
Now with a 178" top gear, I only need to spin at 75 rpm to hit 40 mph down a 10% hill.
I'm probably not going much faster than if I was freewheeling.
But at no time do I need to overspin to get the fastest possible mph downhill.
That I find is the advantage of ultra high gears.

If you want minimum road clearance derailleur cage-road try a recumbent trike with a 20" back wheel.
The bottom of the cage can be level with the wheel rim.
But it was very rare to actually catch it on the ground.
Grass was common .....

YMMV .........

[RickH]

I guess it is swings and roundabouts with the 1x; the total capacity of the RD isn't necessarily big enough to run even a double chainset with that cassette, so potentially the tension pulley is further forwards and upwards from its lowest point than it might be when using a double or triple.

I'm not sure that you could use the SRAM 1x mechs with a double as they are of a very different design to the 2x versions - straight parallelogram (rather than angled) and the top pulley is offset much more behind the pivot, so it swings down as the bottom of the cage swings forward (& of course up as it swings forward). I don't know what effect that has on capacity compared to a modern sloping parallelogram one with a top pulley nearly in line with the pivot. I also don't know if the 1x12 cages are significantly longer than the 1x11 as I don't have any to measure (all donations gratefully received! ).

[Mick F]

The online gear calculators don't work for a triple 10sp with a SA3p.
Here's my ninety.

What's your technique to avoid getting confused with all that choice Mick ?

Technique is to generally stay in 2nd gear with the SA.
This is direct drive.
1st and 3rd get used occasionally to extend the range rather than mix and match through it all.

If I'm on a very steep hill, I'll flip the SA to 1st and work my way to the big cog 28t = 16"
Then, if it stops being so steep, I'll change from the 28t to the 24t which is half-way between 28t SA1st and 28t SA2nd .......... if you can grasp the idea!

3rd SA usually only gets used when I run out of cadence. The top gear of 61/11 isn't high enough on a 406 wheel, so I like to flip it to 3rd knowing that I'll be going down some hills.

Yes, generally in 2nd SA and use it to extend the top and the bottom.

I wonder that a "normal" bike with a triple, could be changed to a single by using the Sturmey Archer system. Not enough for a hilly area like we have here, but it could be ok normally to use it instead of the triple chainset.

Say 8sp or 9sp single with a SA 3sp???
It could work.

[Mick F]

I've found I work less hard downhill now I have +130" gears.
When I topped out at 100", I used to overspin (+100 rpm) to try and get over 30 mph before starting to freewheel.
And I found I was hitting around that speed on roughly 5% hills which are fairly common.
Now with a 178" top gear, I only need to spin at 75 rpm to hit 40 mph down a 10% hill.
I'm probably not going much faster than if I was freewheeling.
But at no time do I need to overspin to get the fastest possible mph downhill.
That I find is the advantage of ultra high gears.

If you want minimum road clearance derailleur cage-road try a recumbent trike with a 20" back wheel.
The bottom of the cage can be level with the wheel rim.
But it was very rare to actually catch it on the ground.
Grass was common .....

YMMV .........

I agree with all that!
My rear mech is an inch off the road - ie level with the spokes. Not good for the chain in the rain and the winter.

[colin54]

Thanks for the reply Mick, that's interesting it makes more sense to me now.

[Brucey]

I wonder that a "normal" bike with a triple, could be changed to a single by using the Sturmey Archer system. Not enough for a hilly area like we have here, but it could be ok normally to use it instead of the triple chainset.

Say 8sp or 9sp single with a SA 3sp???
It could work.

that is really what the system is meant for; in some bikes you can't easily fit (or don't want) multiple chainrings. Also the 'front shift' can be made whilst stationary and the shift intervals are different.

On the latter point, not that many folk worry about these things but the x4/3 increase with each IGH shift is not easily replicated in chainrings; this would involve (say) chainrings of 27, 36, 48T, i.e. the inner to middle interval is a fair bit smaller than the middle to big interval. Ratios that use this pattern are sold, but IME this renders the shifting incredibly sensitive to the setup; i.e. this will only work with the right FD, and with chainrings that have every shifting aid going. By contrast a set that uses (say) 27, 38, 48 can be made to shift well without a lot of aggro. I tend to use the latter kind of triple layout where possible, rather than enslave myself to a fussy setup that needs the exact correct parts in order to work.

The gear ratios with both setups

http://ritzelrechner.de/?GR=DERS&KB=27,36,48&RZ=12,14,16,18,21,24,28,32,36&UF=2170&TF=90&SL=3.1&UN=MPH&DV=gearInches&GR2=DERS&KB2=27,38,48&RZ2=12,14,16,18,21,24,28,32,36&UF2=2170

are not so different that most folk would notice much difference; the front shift quality however, without a perfect match in the parts, couldn't be less alike.

cheers

[Tigerbiten]

The SA hub is a reasonably common setup for a recumbent trike with an extended range because it basically gives you a 0th and 5th chainring.
With a 20" back wheel then 30-??-53 works, 40 is the ideal size for the middle rig but 42 shifts better.
I was tempted to go with type of setup when I upgraded my bent trike, but I would of ended up with three shifters under my only hand.

That's why I ended up with my Rohloff and Schlumpf High Speed Drive combo.
The Rohloff is really a 7 speed hub with a 2.45x internal step down for it's 14 gears.
This matches up well with the 2.5x step up of the HSD for a 14-7 shift pattern or 21 unique gears.
I ended up with twin chainrings because it let me keep my sub 10" first gear while lifting my overdrive speed from ~14 mph to ~20 mph.
That now gives me a 14-3-4-3 shift pattern.

[Mick F]

Ebike?

Given the quoted small chainring - it's most likely an eBike with a gearbox increasing the gear ratios.

No, it wasn't an eBike.

Saw it outside the pub yesterday evening.
Not able to chat to him, but as I left, I had a very quick look at the bike.
I had to be quick because Sailor-the-Dynamite-Dog was on a mission to get going, as he'd been stuck in the pub for an hour!

Any road up, it was definitely an eBike, and more than likely had a gearbox. I'm not well up on these things, so a quick glance was insufficient.

[Vetus Ossa]

My ebike came with a 10-50 cassette. 16t drive sprocket and 1x11.
The cassette was useless for the type of riding I do (mostly road) so sold it and replaced it with a lighter 11-40, which is perfect. There was no way I was ever going to use the biggest two sprockets.