el forestero

I currently ride a hybrid with 48-38-28 chainrings and an 11-32 cassette. I live up a 30% grade hill that cars sometimes have trouble driving up. I prefer to use the 28/32 gear to make it up, particularly after a 100k+ ride. I can barely make it up the hill in the 28/28 gear even when just popping down to the local grocery and back.

Been thinking of buying a new bike someday, and have been looking at the drivetrain possibilities. Never ridden a 2x before. Wondering what others' experience has been with gear ratios on hills. The 28/32 gear I like to use on my hill is about a .88 ratio, and of course the 28/28 is a 1 ratio. The 2x compact drivetrains commonly have 50/34 chainrings and 32/x cassettes. On such a drivetrain, the easiest gear would be 34/32, which is a 1.06 gear ratio.

Given how much harder my hill is when using a 1 ratio gear than a .88 ratio gear, I'm a little apprehensive about moving to a drivetrain where the easiest gear ratio is about 1.06. I doubt I'll have access to a 30% grade hill when test riding a bike to check it out before buying. Interested to hear what others' experiences have been switching to 2x compact drivetrains and tackling steep hills.

By the way, is it "chainrings" or "chain rings", and how do you know? When I search for the previous sentence on google, tons of articles containing both spellings turn up. But neither spelling shows up on dictionary.com.

andrei_r

Considering you need to go up a 30% grade, but also do 100K rides, I'd stick with a triple crank and get a smaller granny chainring (that's how I choose to spell it despite my browser trying to correct it), a 26 or 24T. Unfortunately a new bike with a triple crank is hard to find these days except for the most entry level models. In a double, something like a 48-32 with a wide range cassette(11-36) will give you a similar range to what you have now. In a 1x maybe something like 38T front ring and a 10-42 or a 10-44 or the new Eagle 10-50 cassette, but that smells too expensive.

DorkDisk

The only exact aspect of cycling is the gearing. The math does not lie. If you need X gear inches, going to the newest hi end double with >X is not the solution. You need X gear inches. No amount of marketing helped my old creaky knee up over a hill ever.

Clyde1820

Consider the following setups (in gear-inches) @ BikeCalc.com:

1. 700x38mm, 28/38/48T with 11-32 cassette: high 119.81, low 24.18.

2. 700x38mm, 28/38/48T with 12-36 cassette: high 109.92, low 21.43.

3. 700x38mm, 22/32/44T with 11-32 cassette: high 109.92, low 18.96.

4. 700x38mm, 22/32/44T with 12-36 cassette: high 100.85, low 16.76. (The "low" here is 30% lower than the 28/38/48T with 11-32.)

el forestero

Thanks for the helpful suggestions, folks. Will plan for the likelihood of needing to swap out the cassette and/or chainrings on whatever bike I buy to get that granny gear.

Bryan C. 

I went down this road with my Giant Escape. My local trails are mostly fire roads up never ending foothills. Originally had a triple up front. Swapped to a 46/32 double crankset with a wide range 11-36 cassette and a 40 tooth expander cog which required a wolftooth roadlink. Did the conversion pretty cheap overall.

Might have been cheaper to run a 2x Shimano SLX MTB style drivetrain but I wanted a road drivetrain for higher gearing at the top end. Generally speaking, MTB drivetrains will give better climbing ratios and road drivetrains will be more about top end speed (YMMV). Many ways to do it although its just added expense on top of a new bike purchase.

el forestero

Thanks for the heads up on the expander cog and roadlink. Wasn't aware such things existed. Nice to know about these options.

fietsbob

If cog and chainring are the same tooth-count,
then it's like a chain drive unicycle with an extra wheel .

Every rotation of the pedals turns the wheel once.