How to select your chainring for a Street Machine GTe with Rohloff

After riding my HP Velotechnik Street Machine GTe I realized that I want lower gearing than stock.

My stock setup is 46T chainring and 16T sprocket on a Rohloff IGH.

Gears from 1-7 are quite noisy and feel "draggy". The noisiest is #7. My cruising gear on flats is somewhere between #7 & #8. Direct drive on Rohloff is #11. 

Ideally, #11 should be my main cruising gear.

First I went to Sheldon Brown's gear calculator and figured where I was at.

For 26 X 1.5 / 38-559 / MTB tire with 155 mm cranks

With Custom Sprocket(s) Cassette

With Rohloff 14-speed Speedhub Rear Hub

Low	2	3	4	5	6	7	8	9	10	11	12	13	High
19.9	22.6	25.7	29.2	33.2	37.8	42.9	48.8	55.3	63.0	71.5	81.2	92.4	104.9

So my cruising is done between 48.8 and 55.3 Gear Inches.

So this would be my "ideal" setup.

For 26 X 1.5 / 38-559 / MTB tire with 155 mm cranks

With Custom Sprocket(s) Cassette

With Rohloff 14-speed Speedhub Rear Hub

Low	-	-	-	-	-	-	-	-	-	11	-	-	High
13.5	15.3	17.4	19.7	22.4	25.5	29.0	32.9	37.4	42.5	48.3	54.8	62.4	70.8

If I would like to move my cruising to gear #11, I would need 33T chainring and 17T sprocket. But Rohloff insists on 38T chainring as the smallest with 16T cog, as going smaller would go beyond 2.4 ratio suggestion from Rohloff. What to do?

Doing more research I realized that Rohloff recommendations includes tandems and super fit riders who can really crank on their pedals. In recumbent situation I don't have jolts of force applied to the pedals (I can't stand on them, I am just "spinning").  There are articles that suggest you can go lower in gearing, but Rohloff will not honor the warranty.

So, if I decide to go with "unapproved" ratio on gearing, what are my options for chainrings and sprockets?

Standard sprocket from Rohloff is 16T. For lower gearing they have a 17T sprocket available.

17T sprocket costs $50-60 USD, then you need a chain whip ($10-30 USD) and special Rohloff tool to remove it ($53). 

What if I leave the sprocket at 16T, and just change the chainring?

T.A. Specialites does make a 33T chainring, but it is designed for inside of the shiftable cluster. It might work, but I don't want ramps for shifting on the chainring.

For 34T chainring, there are more choices. Again, I am avoiding rings with pins and ramps. You can have a Surly stainless steel chainring, or numerous aluminum ones. The hardest aluminum alloy is 7075-T6.

How does aluminum  compare against steel? Surly uses 304 steel. It is harder than 7075-T6 aluminum, but also it is heavier. As I am going for reliability, so weight is not that significant for one piece. I would go with Surly. Surly is also reversible -  just like the Rohloff sprocket.

For $30 I can get a Surly chainring and get much closer to the "ideal" range.

For 26 X 1.5 / 38-559 / MTB tire with 155 mm cranks

With Custom Sprocket(s) Cassette

With Rohloff 14-speed Speedhub Rear Hub

Low	-	-	-	-	-	-	-	-	-	11	-	-	High
14.7	16.7	19.0	21.6	24.5	27.9	31.7	36.0	40.9	46.6	52.8	60.0	68.3	77.5

Would this work? There is only one real way to find out.