A little update on the My S40 crankset:
As I had shared earlier, I have been ocassionally spinning out on the 42T that came stock with the S40. This was not an issue on solo rides but on a fast group ride or a race it was an issue. Recumbents are fast downhill and getting passed by roadbikes on a gentle descent becuase I ran out of gears is humbling to say the least. I really like the 1x gearing but I wanted a little more on the top end without having to invest in an expensive XD driver hub or a double shifter and front derailluer. I just wanted to add 4 or 6 more teeth to the chainring.
The challenge with the SRAM Apex 1 crankset is that it only provides three chainring size options: 40, 42 and 44 . It also does not accept third party chainrings because the BCD (Bolt cycle diameter) is asymetrical and proprietary.
I therefore searched on ebay and found some affordable narrow-wide chainrings by a Chinese brand called Deckas using 104 BCD for only $30. They are also available in a wide variety of sizes from 32T all the way to 52T. I decided to first try a 48T chainring. And considering such a low price , and if climbing becomes a challenge I may later try a 46T.
Now the next problem was a matching crankset. Again on ebay, I found an affordable crankset called IXF but due to shipping issues the seller cancelled. I ended up buying another modular Chinese brand direct mount Crankset that looks like a copy of HOPE cranks or Zrace brand. This was cheaper to ship, becuase it packs into a smaller box. It includes an English threaded BB compatible with a Shimano Hollowtech II for 68/73 bottom bracket shells. I am not sure about the quality. Only time will tell.
Considerations:
1.
Chainline: The SRAM Apex1 that came with the bike had a 45.5mm chainline. The new crankset was rated at a chainline of 48.5mm. For good shifting, I had to make sure I retain the original chainline or come close to it using the BB spacers. I installed a 2.5mm BB cup spacer on the drive side and two 2.5mm spacers on the none-drive side which brought the new chainline to 46mm which is 0.5mm off the original. Not perfect but close enough.
2.
Chain length I was going to have to get a longer 11-speed KMC chain becuase it needed 4 additonal links added to the original chain. So I also ordered another KMC chain.
3.
Crank length: The new Cranks did not offer 165mm arms. Only 170mm or 175mm. Oh well, I was back to the 170's that I had ridden for years. No problem.
4.
Q factor: The crankset spindle is rated for MTBs so a bit wider Q factor. It was going to increase by 18mm. Not a big problem.
Additionally I changed my shoes to one size higher(45) becuase I was getting hotfoot while wearing my older 44 size shoes. I tried moving the cleats towards the middle of the foot but the problem persisted. Then after some research, I noticed that when I undid the straps it eased the discomfort and learned that my old shoes were too snag. I have a wide foot. This problem was there even before I got the S40 though.
My first test on a short ride today felt good. Iam seeing good potential. I think I am generating more torque with the 170mm cranks and my cruzing cadence has not dropped too much, may be only by about 5 rpms. I will see with a longer test.
Here are a few pictures :
Installed:
Chainline: