ken cummings

I did a clumsy search and did not find much beyond Sheldon Browns' comments on really low gears. I have a 22 front and 34 rear on my touring bike and find hills around here that stop me cold. Years ago I had a Miyata 1000 touring bike with a 38 toothed sprocket on the rear. Is there any system these days that has sprockets like that or even better? Also in the early days of mountain biking I saw an ad for an adapter that let you attach a 12 rooth sprocket in place of the littlest/third chain ring. Any old timers remember that one? I would like to keep my touring bike somewhat normal and not have to add a 5 to 1 reduction gearing jack shaft like an HPV friend of mine who built a sand bike. If you need to know what I am running check www.bgcycles.com and look up the specs on the BLT. Thanks.

Rowan

Apologies, Ken, in advance... but what type of machine are you using? A BLT with training wheels?

I have a 22-32 granny on my diamond frame and that is good for around 4.5km/h mashing. I wouldn't even consider a 22-34 as it would be just too slow to balance or I would be spinning way too fast.

I have heard of 20T ring, and I recall from the deepest filing cabinet something about an adapter for putting sprockets on the crank spider... but really, I don't think you will be getting anywhere even slowly -- without falling over -- with that set-up.

joejack951

Rowan, if you can mash a 22-32 at 4.5 km/h why couldn't you spin in a 22-34 at the same speed? I've used a 22-34 on some really steep and loose terrain on my MTB and did just fine as long as I kept my weight forward and my butt on the seat.

Sorry, Ken. No good answer for your question though. I guess if you were really serious about getting lower gearing and nothing off the shelf would work, you could look into having a 20 or lower tooth chain ring machined to fit your crank. It wouldn't be cheap though.

26" wheels would get you slightly lower gearing if they'd fit.

Falkon 

I have a 12-25 cassette and a compact crank on my commuter, and I haven't found any hills that stop me yet. The same was true while I was riding my 42x15 fixie.

Rowan

Because I find the spinning throws off my balance (and it need only be another 5 or 10rpm above "mashing"). It's like trying to do a track stand with a single-gear, but while you keep on pedalling... at least for me, it seems so.

carlton

You must be climbing some hellacious hills or carrying extremely heavy loads not to be able to make it with the gears you have now. Kinda pricey but one of these would give you about any kind of gear you desire. I know there are some pretty steep inclines in Northern California. I've had 8 power driven wheels spinning on dry pavement while trying to reach the top of a hill over by Headlesburg going up to the Gysers. {18 wheeler with 80,000 lbs gross weight with 500 horsepower engine} Good Luck. Nice bike.

https://sheldonbrown.com/harris/schlumpf.html

2_i 

I run 20 upfront and 34 in the rear. I utilize the combination or its vicinity when going uphill on a loaded bike in snow.

The general problem with going down in chainring size is that tension in the chain increases. I do not know where the limit for chain snapping is, but a high tension combined w/small ring/sprocket size imply a rapid drivetrain deterioration. For drivetrain durability, it may be better to go up in the rear than down upfront. Obviously, the gear gain is less rapid in this fashion.

ken cummings

Thanks for the responses. I recall the Schlumpf gearing now. I am OK down to 3 MPH. We have several hills over 20%. I am in the 60s and only average club level fitness. I have been over the hills to the Geysers a few times and take an hour or two to go over either side. Try taking that big rig to the Geothermal fields on Pune Flat where you exceed 22%. Glad somebody remembers the old adaptors. A friend once welded a monster chainring on the biggest sprocket of his cluster. He couldn't shift it but could climb some amazing slopes.

Rowan

Depends on how long the climbs are... but there is no shame in getting off and walking irrespective of age or fitness.

2_i 

https://abundantadventures.com/quads.html

CrosseyedCrickt

Coming from a guy who works in *this* industry, I can tell you right now that having a single chainring/cog specifically made for you is not worth the money, unless you know someone who wouldn't mind doing the g-job for you at a machine shop.

2_i 

https://mgagnon.net/velo/pedalier4.en.shtml

Dr.Deltron

Get the Schlumph Mountain drive. All the lowest gears you could ever want!
I have one on one of my trikes, and unless you are on a steep incline, something feels "broken".
In otherwords, there is no resistance when pedaling, unless you are pointed UPhill!

CBBaron

I can walk pretty easily at a 3 mph rate. I wouldn't expect something smaller than a 22x34 to be moving much faster than that. I think it is time to walk.
Craig

Michel Gagnon

22/34 is indeed the lowest gearing you'll be able to find commercially. Suntour used to make a freewheel with a 38-tooth large cog, but that was back when it was almost impossible to get a chainring smaller than 40 (and definitely impsosible to get one smaller than 32), and it required special derailleur and derailleur mounting. So right now, 34 is the largest cog you'll be able to find and use with modern derailleurs.

For rings, Shimano used to make a 5-arm mountain crankset back in 1995, which allowed a granny of 20. Right now, the only commercial option is to buy a TA Carmina crankset. And you'll go down to 20, only.

I installed a https://mgagnon.net/velo/pedalier4.en.shtml]Quad Tamer[/url] on my tandem. The Quad Tamer can go as low as 17, but it only installs on a cransket equipped with 130/74 or 110/74 cranks (i.e. 105 and similar road cranksets). So you would need to install a new crankset for that.

max-a-mill

you can find older mtb cranks (94bcd?) that will take a 20t granny. below 20-34 and your really in danger of being passed by people with walkers

i have a set, for when i go on tour in the rockies.

i bet flea-bay might have something used.

one thing i learned singlespeeding: a good walk will stretch out your back nicely once in a while and give your legs a little break from the spin!

joejack951

But can you walk up a 20+% grade pushing a loaded touring bike at 3mph?

You mean people pay to have things machined for them? (it's nice having a machine shop at work)

HardyWeinberg

I don't about the limits on what chainrings and rear sprockets a rohloff can work with, but holy cow, you can get some *really* low gear-inches to show up on Sheldon Brown's calculator w/ 22t chainring and just about any rear sprocket:

https://www.sheldonbrown.com/gears/internal.html

MMACH 5

Oh yes there is.

banerjek

Consider a trike. You can keep the tiny rings up front and the huge cogs in back. If you get an 18" or 20" rear wheel, you'll get a huge gear reduction from what you have now.

ken cummings

Good call Banerjek. I have an old rusted long-wheelbase trike I will repair one of these days. Then I can add the goodies my forum friends have put me on to. next stop pedalling up the side of the Luxor Casino in Vegas.

Yes I can stop and get off when it gets too steep and I do. It is just that I do not like giving in to the hill. And it is so hard to get re-started on very steep slopes once my breathing has dropped enough.

edtrek

This is a dup reply I just made on the other gearing post. My Surly LHT will have a 20/36/46 up front, and an 11/34 in the back. This results in a lower low gear than my 26" MTB, and a higher high gear than my Trek1100 road bike.

I've been puzzling for a while over how to effectively present gear-inch chart (front/rear*27) and how to present the optimal path through the effectively usable gear, and I've ended up with this sort of a chart:


I'd sure appreciate any critique or suggestions about a way to present this info. I think it's a key issue in bicycle popularity- the market sells people bikes with 27 gears and no info or briefing on how to use them.

By way of explanation, the chart indicates the gear-inches resulting from every gear combo.
The effective path through the gears is indicated by the green color and the smaller sequence numbers.
The large-large combos are not available, there's not enough chain to accomodate them.

So, you'd start in the granny gear F20 / R 34, and click the rear derailluer twice to get to 3rd gear.
Then, you'd upshift to the middle chainring and downshift the rear twice, to get to 4th gear.
You'd stay in the middle chainring for 5 gear shifts, resulting in 9th gear at 61 gear-inches.

To get to the 10th gear, upshift the chainring and downshift the rear derailleur for a 10th gear of F46/R18.
Continue shifting the rear der. until you get to 14th gear - which, if you get there, probably means you're descending and light.

2_i 

My cogs are 11/13/15/17/19/21/23/28/34 and rings 20/34/46. The cassette is organized to keep me long within one front gear. Since you write about plans rather than actuality, have you thought about capacities?

edtrek

I mention "my surly lht will..." because I pick it up from the LBS in a few days. The potential of cassette variation is very interesting, though.

carlton

Assuming I needed the lowest gear to get rolling and was able to progress all the way to top gear I would use this shift sequence.

20/34--20/28--20/24--20/21--20/18--20/16--36/24--36/21--36/21--36/18--36/16--36/14--36/12--46/14--46/12--46/11