Hybrid bike - would like to switch to a single front chainring, what are my options?

Question

I have this bike (19" size):

http://www.bikesdirect.com/products/motobecane/elite_trail_x4.htm

I'm doing some things to it to simplify it and reduce its weight for my city commute I've been doing for about two years. I've replaced the front suspension fork with one that's fixed and of the proper geometry, and this helps in both areas.

Next, I'd like to focus on gearing and save both complexity and weight. It's currently setup as it came from BikesDirect, so this means:

Crankset: SUNTOUR CW9-XCC 28/38/48T 175MM(18~23")ALLOY BLACK CRANK

Front Derailleur: SRAM FD-3.0-A1 TOP PULL

Rear Derailleur: SRAM RD-X4-A1 SILVER CAGE

Cassette/Chain: CKHC 11-32T-8spd / KMC Z-72

I'm considering replacing the entire crankset - but in the meantime, I'd like to go from 3 chainrings to 1. I don't use the largest ring at all in my commute, and I find myself using the granny gear in a couple specific situations, and the easiest half of my middle ring. Typically, my bike just stays on the middle ring unless I'm doing a serious climb (which happens once on my commute). Basically, I don't need speed on downhills as I'm not racing anyone so I'm typically using the brakes to moderate my speed on big downhills anyways. I need a decently easy gear for a small portion of my ride (getting up the Manhattan bridge) but otherwise it's very level riding.

My questions:

1. Is there a single-ring option that would give me a 2/3 of my easy gear and the easy 1/3 of my middle gear that I could direct swap onto my existing crankset and remove the other two chainrings entirely?

2. Is this setup safe (1x8) if I remove the front derailleur and shifter where if I shifted to the extremes of my cassette I wouldn't drop my chain - and if not - do you recommend something to go on the front to help hold it on without having to keep the front derailleur?

3. If #1 isn't an option, is there a crankset I could switch to that would make this setup possible?

Thanks!

Edit: in a brief spin around the internet, I found some single-chainring options that I have no idea of compatibility:

https://www.bikeparts.com/BPC394186/raceface-evolve-ss-crank-175mm-nw32t-black-9-10-11

https://www.bikeparts.com/BPC169250/sram-gx-1400-1x11-bb30-crankset-32t-x-sync-175mm-red

Seeing as I have an 8 speed cassette, and the first one says 9/10/11 and the second is a 1x11, I'm not sure how compatible these are. Help?!

Answer 1

I suspect you'll be buying a whole new crankset. You may also need to upgrade the bottom bracket as there's not much choice of upgrades if you're starting with square taper parts.

My hybrid had a very similar drivetrain, including suntour cranks/chainrings which were riveted together.

You've already got a fairly wide ratio cassette for an 8 speed (I run the shimano equivalent) so you might struggle to get the range you need. Perhaps something like 11-34 (the widest range I've seen on 8 speed) with a 32-36 tooth chainring would do it. 8 speed casettes are cheap and consumable so swapping out to get the extra bottom end might help you. The alternative of going for a full 1x9 system would of course mean a new shifter and probably cable.

You should probably make up a spreadsheet of all the gear ratios you have/use and those you'd get in your 1x8 suggestion. And you can try running just in your middle chainring to see how much too hard 38 is.

The actual weight saving though, on a hybrid which probably has a heavy frame, is unlikely to be worth it, every assuming better/lighter cranks to go with the reduced chainring weight.

Answer 2

The thicknesses of 8 and 9 speed Shimano cogs differ by 0.02mm (http://www.sheldonbrown.com/cribsheet-spacing.html). I would say that the same chainwheel is compatible with 8 and 9 speed chains.