scale

Im back on this kick. Pulled my folder out and plan to swap out the steel seat post this year and likely want to change the gearing the rear. I think the rear is a 14t or maybe 15t. Are the twentys geared the same as a full size 3 speed? I have swapped out to a 22t on those and its been ok. Just wondering if thats too aggressive on a twenty. Wondering what SixtyFiver runs? I know he swaps out his stock gear and runs in the top gear 99% of the time and uses the 2 other lower gears for the hilly stuff.

rhenning

The original gearing is just fine. First works well for getting you up hills, second will do most of your riding and third will get you fast enough for down hills. You may want to post your question in the folders section.Roger

thorstein

There's a 15T cog on my '69 Twenty that does pretty well most of the time. The only time I want a larger cog is going up the 7% grade hill on my way home from work.
I agree with rhenning though, 2nd is a good cruising gear & 1st does pretty well with most hills.

sykerocker 

I swapped my rear cog for a 16t, and the bike has a 44t chainwheel. That combination gives me 55 gear inches in second, which I find reasonably useful for the flats.

This from a guy who's standard is to run a 23t rear on his 28" wheel roadsters (56 gear), and 22t on his 26" bikes. I've always been one to set up a three speed in the mid/high 50's gearing in direct drive, allowing me to run the same pedal cadence on my commuter bikes as I do on my derailleur road bikes.

3speedslow

Gearing for the R20 is based on the 20” wheels. It’s okay to bump up the tooth count in the rear if you want. Might have to go to a longed chain if though.

Micro adjusting Seatpost change was great for me as it made the saddle more secure on the bike.

tjfastback66

This is a good question and quite honestly is a bit over my head at the moment.
I also am working on a R20 project and the rear gear has 22 teeth with the front chain gear stamped 44T. Just wondering if that gearing is good for overall use..

sykerocker 

That's 40 gear inches ((chainwheel/freewheel) x wheel diameter in inches) - which is getting into a climbing gear. That's getting awfully close to my Twenty in first gear (36.3).

tjfastback66

So Sorry but I neglected to indicate that the rear hub is a Sturmey Archer AW 3 speed internal gearing...

sykerocker 

Then (if my memory is correct, AW's do a 1/3rd down into first, and a 1/4 overdrive into third - correct me if my memory is faulty) that'd mean you're first gear is approximately at 24. Plan on climbing any trees?

To put things into perspective, the old classic 70's ten speeds running the usual standard 42-52 chainwheels, 14-28 rear cluster, and 27 inch wheels had a gear range from 40-100. Up that to, say, a World Voyageur (I'm thinking of that because I had one back then) with a 14-34 rear, would get you a 33 gear ((42 / 34) x 27). Which I remember would climb bloody anything, even with full panniers, handlebar bag, and a tent strapped to the rear rack.

Addendum: While reading the updates to this thread today I also had my other folder, a first generation Dahon single-speed coaster brake model, on the stand checking it out for a trip that I'm going to be doing this weekend. While I've always felt the bike was a bit under-geared (it climbs hills nicely, but I'm coasting on the flats within five or six pedal strokes because I've outrun the gearing), I finally took a moment to figure out what the gear it comes with. 46 tooth chainwheel, 16 tooth rear sprocket, on 16 inch wheels. 46 gear. No wonder why I'm always outrunning the gearing on the flat. I'm starting to consider changing the rear to either a 14 tooth (52 gear) or 13 tooth (56 gear), which would bring the bike in line with the rest of my commuters. Yeah, I'd give up some climbing ability, but I never use that bike for more than a two mile commute on the flats in the towns that I travel to.

tjfastback66

Syke - Thank you so much for sharing your knowledge on this subject, I think that I should down size the rear gear then. But first I need to get the bike road worthy!

tjfastback66

Found a 17t SA rear sprocket for the Twenty today. So If I hear you correctly {(44 / 17) x 20} = about 52 gear inches in 2nd. First would be about 34 gear inches and Third would be 64 Gear inches? Rear hub is a SA AW.

52telecaster

Subtract 1/4 for the lower gear. Add 1/3 for high gear. Essentially you add an extra third each time you shift up on an aw hub.
so on a 26" bike with 22-44 gearing you have 39-52-69 1/3