1x (one-by?) drivetrains
 

This might be more appropriate for the 'road' forum, but it's an old bike under discussion and I trust the collective judgement of C&V more anyway. :thumb: Planning the build for the atala I posted a few days ago, I've been having a lot of trouble settling on the drivetrain.

I've got a 28-38 double on my current bike, along with a 28-13 seven-speed freewheel. I've noticed that the only time I ever use the small chainring is when I'm pulling the toddler trailer up a steep hill, and then I only ever use the lowest possible gear. After cresting the hill it's back into the big ring. I don't feel too limited by the top ratio on the bike, as I can spin about 30MPH on the downhills and I'm not ashamed to coast.

I want a very low granny gear for the baby-pulling. While I feel like it "should" have some really tall gears just because it's a road bike, I'm pretty confident I'd almost never use a 50 or 53 chainring. ( Note that 120RPM burst with 50/11 is right about 43MPH :eek: )

A triple crank seems so awkward, particularly since a tight cluster would put my cruising gears right on the low/middle chainring split. A wide cluster would mean I would almost never use anything but the middle ring. Similar problems crop up when considering a compact double.

I'm beginning to think that the best gearing for me on this thing would be something like a 40T single ring and a 9 or 10 speed MTB cluster like a 34 or 36 - 11. I'd have the low gears I want, a couple higher ratios than my current bike has, and I wouldn't have to mess around with a front derailer (thanks Sheldon) or left shifter at all. The biggest drawback of this plan is that it seems like it'd make the bike look stupid or somehow feel "wrong".

So, tell me this, C&V... what do you think about 1 x N transmissions?

I have a couple of 1x9 bikes. The one hitch in the plan is that sometimes throwing the chain can be an issue. Especially with a wide 9 speed MTB cassette. On one bike it never happens. On another, it happened enough that I put a bashguard on the outside and a sharktooth chain guide on the inside.

For some reason, I find the look of a 1xN drivetrain to be appealing. Not that looks is the most important thing in a drivetrain.

jim

Actually, you may want to consider a Shimano Megarange freewheel. You can buy 7 speed versions fairly cheaply. They give you 6 cogs between 11T and 24T, then have 34T granny cog for pulling that trailer up those hills.

I'm currently accumulating parts for a city bike for a friend. It'll be built around a Motobecane mixte (120mm spacing). I'm planning to set it up with a 5sp freewheel and a single chainring around 44t (1x5). With 700c x 32mm tires she'll have a range of approximately 42 to 85 gear inches and a very comfortable cruising gear of 70 gear inches (44x17). I'm setting it up with a long cage Suntour RD and single barcon.

MrEss, one bys are fine, take a look at this gear chart. It may not exactly match your tire size, but will give you a decent comparison. You may be best served by keeping what you have.

Brad

my cdale has been 1x7 for a long time and will be 1x8 next spring. i like 1xN drivetrains. i have never dropped a chain and i hop curbs at speed regularly on my commute.

edit: good derailleur tension is key i think

1x5-7 are better for chain retention than 1x8+, due to better chainline throughout the cluster. Regardless of the number of speeds, you'll want your rd dialed on a 1xn bike. (any bike, really, but particularly a 1xn to avoid dropped chains.)

personally, i've never found 2xn drivetrains to be overly heavy, or complicated, so i would just leave the double on. If i were building a bike from scratch and wanted to simplify, i'd look into eliminating derailers altogether, and get a 1xn IGH.

fwiw, you never use the inner ring on your 38/28 because that's a silly low gear on a double. I know this is fashionable among the "elegant"/retro set, but that's b/c they worship ppl who live in the pyrenees, as far as i can tell. Those of us who are not living in alpine areas really should gear-up a bit, imo. Maybe not to race-style ratios, but having a 38/13 as your top gear seems ultra-low, to me.

-rob

Maybe I'm just a weakling, but I really enjoy super-low gearing. I usually cruise around 17~18MPH in the 38/21 or 38/19 gear for 50ish gear inches, spinning pretty fast. Then, that 1:1 gear is great with 75lbs of trailer behind the bike! The 28/38 double is the left half of a cheap MTB triple I put on my Ross to gear it down back before I learned to be a retrogrouch. I just never ever needed the big ring on the stock 39/53 double.

I'm planning on keeping the silly 28/38 double on my Ross, but need to decide what to put on the new bike... that's where I'm considering the 1x9. I've thought about a modern IGH too, but I feel like an Italian bike with a derailer hanger wants / deserves derailer gearing.

We've got a 34,24,22,20,18,16,14 MegaRange freewheel with a 34/50 compact double on my partner's bike and it's great for her. It's not so great for me, though. I never use the big ring when I ride her bike and wish there was something between the 24 and the 34 for unloaded climbing.

Thanks for all the input pro/con the 1xN idea... keep it coming!

if youre spinning like that and maintaining those speeds, you're no weakling! i agree re: your atala getting a derailer in back; try a 48/36 or some such up front? i assume only the Ross will be doing trailer duty; perhaps you can put those rpm's to better use on the atala, with an almost-big ring?

-rob

I also like 1xN setups a great deal. My wife's mixte is a 1 x 6 with a SunTour Cyclone MkII RD, and my Paramount is a 1 x 5. I have a plan for a 1 x 9 with a single brifter.

Neal

I ran one bike 1x7 at one point and I liked it. it's not a bad setup for an area mostly flat but with some hills here and there.