Finding that right gear ratio
 

Ill just get to it.

will be riding a singlespeed up front with about 42-44 teeth due to the 144BCD. I prefer 144BCD as I've heard that this offers the more stiff and ridged foundation for cranking. The rear cluster is a mystery to me and there are two or three things I'd love for this gear ratio to accomplish. Here it is.

I only have one bike and would like to double my one bike for training as well. I'll already be missing the top end speed of a 53 tooth chainring. Is there a small enough ring that you could install in the rear that will emulate the pull and thrust of a 53tooth chainring? If not can you get close?

Second I live an a extremely hilly area. So having several rings that are designated to climb with more ease is necessary. In fact the hills are the very reason that I wont just jump to single speed use.

Thirdly is brute force acceleration. Can you find a cluster that offers mid range acceleration to burst in and out of stop signs, intersections, sidewalks, blocks, straights.

Basically if it is possible. Hill Climbing gears down low, Burst of acceleration in the mid range, a small ring that can get darn close to the 53tooth full thrust on a traditional road bike.

Like I said, If possible I'd like this to be my training bike as well. Training alone is one thing, But to keep up in a pack, That top gear is necessary. I'd already be at a lose with the wonky gear ratio as it is. As everyone will be shifting back and forth with their road specific cluster, I'll already be at a disadvantage with a wonky cluster.

Thanks for all the help all
Crisp Bacon for all. If your vegan, then only the ripest banana-nanas

*Wonders if he just described what everyone wants in a cluster*

I have to agree. The OP is describing wanting single speed with multiple gears. Flats, hills, etc.

Some people have gone with flipflop hubs, but that only gives a couple gears difference, and I assume is a bit of a pain to swap.

Keep in mind that it is all about gear ratios (or gear inches, however you wish to calculate it).

42/12 = 3.5
53/15 = 3.53

Those two gear selections would give you essentially the same gearing. If you want a freewheel (single speed), then it is easier to find larger sprockets, although there are BMX freewheels down to 9T. For fixed gear, you can get down to 12 or 13T.

If you wish to go without a derailleur, look at some of the internal gear hubs. 3, 5, 7, 8, 11, or 14 speeds. You can also find multi-speed crank sets.

I'm starting to build a bike around the Sturmey Archer S3X which should give me a 3-speed "fixed". Personally I mash a bit, so I'm going with as high of a gear as I can for the top end, and then allowing lower gears for the hills. And the "fixed" should be an interesting detail.

This is nothing more than the beautiful Princess throwing her handkerchief in the Lion's Cage and promising herself to the man who fetches it out. A Fool's Errand IOW. Consider me the Wise Sailor, veteran witness to the human wreckage of many such threads who declines to accept the challenge.

How low of a low do you want? Are you willing to have a wheel built for this?

If 43.6 or so is low enough, you could build a wheel around a shimano Capreo hub and its 9-26 cluster.

43 up front would get you within 1.1 gear inches of a 53x11.

Your low would be 43.6 compared to 39.6 of a road standard 39x26.

Me, I just run a road triple, and replaced the 32t little ring with a 26.

52/42/26 x 11-26 9speed is pretty sweet.

If only there was some way of changing cogs while you were still moving.

Ahh.. right, single chainring. Regular cassette or freewheel and derailleur on rear.

So... 1x3, 1x5, 1x6, 1x7, 1x8, 1x9, 1x10, or 1x11.

No doubt one could get quite a range if one goes with an 11 speed with 11-28 or 11-32 on the rear. Then choose the chainring that would fit the rider's preference.

Get a big enough cassette sprocket on the rear, and there is no need for the second chainring, but one probably doesn't want to go super-small either.

As mentioned, Capreo goes down to 9T. There are a couple of companies that have also put 10T on their cassettes. SRAM may be one of the big vendors with a 10T cassette and a mountain gear range. But, you're probably better off going with the more standard 11T if you can get the right chainrings.

I find that 144BCD is a bit of a pain to get parts for. 130 is much more widely supported.

So be it. I'm all good with that.

I suppose I could do the original method and purchase a million rings and keep switching them out back and forth until kingdom come. Heck I'll get a composition note book and write a detailed lab description of every different range. Or I could admit to being a novice and ask any more experienced apprentice and/or expert that is willing to share their experience of having done the grim work themselves.

You know how we evolve in intellect right? We write things down for the next generation to read to save time. In turn, we progress because we dont need to put the blood sweat and tears in to learn a lesson.

Don't get me wrong it would actually be very hands on if I could afford to buy a bunch of chain rings and do it myself. But If this is taking the "easy" way out. Well heck, Ill take all the help I can get. Who knows maybe in a couple of years I'll show my respect by helping out another new comer. Remembering how many helped me get there....

I had a fix gear made that does much if the OP's wants. It has a very long dropout and can handle from a 12 tooth cog to 23 without messing with the chain. I ride it with a 144 BCD Sugino 75 crank (for its track quality roundness and very low Q-factor that my knees love), usually on a 42 tooth chainring. This gives me gears between 49 inches and 95 inches. I use double sided fiz-fix hubs and carry a cog wrench on the top tube for very hilly rides.

My Cycle Oregon ride up to and around Crater Lake went like this: Left camp on the 17. When the climb got serious, flipped the wheel to 23. At the rim, I swapped the 17 cog for the 12. Rode around the rim on the 12 and 23. Down toward Prospect on the 12 for miles. When the hill leveled out, I took the 23 off and rode into the new camp on the 17 like I started. Spent very little time in the wrong gear. Did have to do 6 flips and 2 cog changes.

Edit: I too got thrown off by the word "singlespeed" and wondered the entire post why the OP was going with a cassette if he skipping the derailleur. But given that I created my first SS by simply taking the derailleurs off, putting the chain on the gear I wanted and shortening it, I didn't question what the OP was doing.

Ben

You probably don't need to go out and buy a bunch of chainrings, just do a little research. I presume you have a 53/39 up front right now. Grind up your toughest hill in the highest gear you can. Take note of what gear you were in, such as 39x17, then go here

HTML5 Gear Calculator

It should default to 53/39 up front. Drag on a 43t, for instance. Play around with different cassette combos. Compare the 43x range to the 39x and 53x ranges Then try it with the 42 and 44, etc.

If you want an off-the-shelf option, there should be road bikes showing up with Rival 1 and Force 1 groups on them fairly soon. 50x10-42 might work for ya.

42 is the magic ring up front, 12-26 out back. If this doesn't cut it then your strength and spin need work. There you go.

If you can't find the right gear in a 1x11 system, it means you forgot to shift.

That's what I use for commuting in the winter. Have to spin up to 150RPM going down a short steep hill in the morning. It works fine for commuting but not very good for a fast group ride. Also not so great when you want to do an easy tide and have a hill to climb. Decent training though.

How fast does the OP need to go?

42T X 12T 700C X 23MM = 40KM/HR @ 90 RPM & 52KM/HR @ 120RPM

I use a triple crank with a single speed wheel, 24/38/50T X 18T.

I spin out at 50KM/HR, more than sufficient for my (flat terrain) needs.

It works for me in the winter. It gets tiresome on a faster group ride though if you've got any long 1 or 2% downhills.

42:21 on a 3 speed IGH? :innocent:

cogs 13~23t now in 3/32 & 1/8 thickness

(Wont find 42t track chainrings)

44/12 = 3.6
53/10 = 5.3

That's a big difference. Never mind the leg muscle needed to lug that speed. I did not factor revolutions though. Do like how someone explained cadence is important. Understand that group rides will have riders of varying levels of fitness. But if I'm getting this right. 42/44t with a 10-12 will be enough to peddle hard with a group? This is intriguing, although it isn't in the budget I may actually get my hands dirty and mess with the gears. There is a really good steep hill right outside my studio. Maybe I will look like a nut job to my neighbors and hit that thing two dozen times in an hour lol.

50x10-42?

which means a 50 tooth ring upfront with a cluster with a range of 10t to 42t in the rear? sorry to be that guy. Lost on what your trying to say here.

Yes, indead. 50T chainring x 10-42 cassette. It's one of the myriad of options for a Force 1 setup.

SRAM 1x road Force 1 and Rival 1 groupsets - first ride video - BikeRadar USA

They don't do 144 bcd, but you could probably live without that, really. If you can't, you could probably run the track crank/bb of your choice if you get a threaded BB frame.

Thanks for the video that definitely cleared some things up. So the 42t in the rear was originally for mountain bike use. Wobbly chains are a real problem. There are alternate teeth patterns for kicking out mud. OK now that's something I gotta read up on. But the chain sticks to the teeth much better?

That's an interesting and unusual set up you're running there, SHBR. Do you have a rear derailer to maintain chain tension?

I've spun my 42-12 over 35 mph many times. 37 at least once. The only way I could justify any taller gears is if I had some long descents, which I don't. Maybe the OP does.

I understand that not all riders care to, or even can, spin these higher RPM's.

I'm using an old 8 speed Shimano 600 tri-color short cage RD as a tensioner.

My rear wheel is 32 spoke, dishless with 72mm flange spacing. In theory, it should be slightly stronger and stiffer than my front wheel.

Its a lot easier for me to slug out some gears but that's because of how I road in my teen years. Spinning is a mystery to me and no doubt works your agility. It took me a week or so to really gear down low to travel up hill faster. And I felt like a goof when people would look at me huffing and puffing up hill with my legs spinning at what looks like to be uncomfortably fast. Thats OK though I was the only commuter that would challenge the hill in question. I'll try to continue to add more emphasis on spinning this next coming spring.