Recumbent - Extremely low gears

I am posting here because I expect less scorn and more sympathy from recumbent types. I want a lower low on my machine. Can I modify a cog to fit onto the smallest position on my triple and how small can it go? Could some kind of widget bolted onto where my 22tooth sprocket goes might let me go down to 18 or even 16 teeth? Decades ago I had a 38 tooth cog on the rear cluster of my mountain bike. Is such still available? A friend once welded a 54 tooth chainring onto the rear cog of his fixed gear bike. He beat everyone up the first hill in a race and was dropped on the next descent.

Some tell me just get fitter. My knees put a limit to that.

Look into chainrings and cassettes meant for touring. They typically have slightly lower tooth counts, compared to road gears. Nashbar (www.nashbar.com) will have lots, or you could swing by your local bike shop.

Are you experiencing knee pain? You may also want to look into getting shorter cranks, and Rotor Q-rings.

I am posting here because I expect less scorn and more sympathy from recumbent types. I want a lower low on my machine. Can I modify a cog to fit onto the smallest position on my triple and how small can it go? Could some kind of widget bolted onto where my 22tooth sprocket goes might let me go down to 18 or even 16 teeth? Decades ago I had a 38 tooth cog on the rear cluster of my mountain bike. Is such still available? A friend once welded a 54 tooth chainring onto the rear cog of his fixed gear bike. He beat everyone up the first hill in a race and was dropped on the next descent.

Some tell me just get fitter. My knees put a limit to that.

The problem with really low gears is that you can hardly stay upright.
With 26" wheels, a 16/34 combo, at a cadence of 60, you're moving at 3 km/h (2 mph). Of course, most people can stay up even down to hardly any speed at all, but at that speed, I'd get off and walk...

How big does your cassette go? If you aren't yet at 34T, a new 11-34 cassette is where you should start.

The smallest possible chainring you can use is defined by the bolt circle diameter of your crank. I think the smallest bcd you can find is 58, which at 2 teeth per inch, would allow a 15 or 16T as the smallest possible. Your LBS might be able to get you a sub-20T ring, if your crank can take it. (It might require a new crank.) HOWEVER, if you used your current 22T, along with with a SRAM dual-drive, you would achieve an effective chainring of 16 teeth in underdrive. This is probably outside of their recommended range of driving gears, but I've never seen one break because of streching the limits. The problem: lots of $$$ for the new SRAM-equipped rear wheel.

Hostelshoppe sells lots of chainrings, and has a how-to page for figuring out which bcd you have. (www.hostelshoppe.com)

What about a low powered electric assist, takes the stress of starting on a slope and on steep hills, used sensibly you will get fitter as you will suffer less damage to the knee.

I've been tossing e-assist around in my head. The thought of adding 35lbs of gear to my bike is daunting though. (motor, cont. batteries)

Not a serious knee problem, just being careful as I do not have medical coverage. I know of power assist and getting off and walking. They just feel like giving up. There is only one hill I have to walk on and a few others I do switch-backs on. Slow is not a problem. The annoying thing is getting started again on a very steep hill after I stop and rest. Please do not suggest coaster-wheels, Never had them, Never will (kudos to 7-Up). I do admire the man who put a controllable rocket engine on the back of his bike. I would try that if only for dealing with tailgating cars :D . I understand that rocket man built the motor for Spaceship One.

I want a lower low on my machine.

Hi Ken,
Just wondering if you would consider a Schlumph Mtn Drive crankset. It goes to a two and a half to one reduction. Its so low on my GTX that I thought something was broken. Then I headed up my driveway and finally got some resistance. WOW, is that some loooow gears. I did a test and rode up an aluminum boat dock ramp that was probably 25-30 degrees. In lowest gear, I was able to "crawl" right up it.
Just a thought,
Dr.D

You can get 17t chainrings from Highpath Engineering (http://www.highpath.co.uk/cycles/products/eggs/01.html)
There may be a US machine shop that can do similar work. If you find it post here.

Want extreme low gears:
http://www.abundantadventures.com/mt_plus.html

He'll get you down to 17 teeth, and up to 5 chainrings.

Try http://www.schlumpf.ch/ they do special adaptors the enable large cogto be fitted to hub gears

Try http://www.mountaintamer.com/quads.html for front adaptors

Try fitting a smaller rear wheel

Does anybody know where to get extra long front deraillers or how to modify existing ones to make them longer so they work on lower / extremely lower gears? so the chain won't rub the derailler?

Thanks,
Garry

Dunno, you may have to make something.

Thanks SteveW and Dr. Deltron. That Schlumpf planetary gear is the kind of extreme idea I was looking for but the $500 price is a bit much at the moment. The other posters who directed me to chainring adapters are more in my price range. When I rebuild my old trike the Schlumpf will be used. By the time I can afford $500 I will be fit enough not to need it except for plowing the back 40.

Try http://www.schlumpf.ch/ they do special adaptors the enable large cogto be fitted to hub gears

Try http://www.mountaintamer.com/quads.html for front adaptors

Try fitting a smaller rear wheel

In addition to the above cited solutions:

Spicer industries has a cassette adapter that lets you mount a chainring to the freehub:
http://www.spicercycles.com/index.cgi?cat=18&cat_desc=Mountain&sub_cat=Cogs

There are still some 14-38T 5 speed Sun freewheels popping up on ebay.

An SRAM dual drive can get you an internal gear hub that also receives a cassette.

You may also have to replace the front deraileur if you change the size of the smallest chainring and leave the largest one as is. The literature that accompanies a new deraileur has info on how large a difference there can be between the number of teeth on the large chainring and small chainring. If you exceed that difference, the deraileur will either work on the outer chainring and not work the inner chainring or vice versa but will not properly work on both.

I would try the rear cluster before messing around with getting smaller chain rings. It would likely need a new front der. and maybe just a whole new crank. With a triple and a 34 tooth cog you should be able to get up most anything in your way. If you have a road rear der. and you go to a 34 tooth largest rear cog, you will likely need a mountain rear der. They are designed to take up the additional slack in the chain required by the wider spread of rear cogs.

Also, try posting in the touring area. Those folks should know about getting low gears.

If you exceed that difference, the deraileur will either work on the outer chainring and not work the inner chainring or vice versa but will not properly work on both.

You're confusing the 'throw' with the spanning ability of the derailleur. A double derailleur might not have enough throw to shift between 3 chainrings, but most bents have triple derailleurs anyway. For 'bent purposes, the real concern is how many teeth difference can they span from smallest to largest rings. Most triples are rated at something like 22-24 teeth difference. If you want more spanning ability, you either buy a derailleur with a longer cage or modify one yourself.

If you don't have enough range with your derailleur, the chain will drag on the bottom of the cage when you're in the granny ring. The results can be annoying if it's just a minor dragging, but you can also bend the cage if the drag is more serious.

I am an experienced shop owner, long distance tourist and engineer. I have experimented with gear ranges as low as 15" of develpoment and I find that for develpments of less than about 20" it is faster, safer and more refreshing to walk for a while. It is true that an experienced ridr can stay upright all the way down to "stall speed" but it is much healthier to walk occasionally to break up long or difficult climbs.

I have toured with 50-75 Lbs of gear, self contained and on some hills so steep that if you pushed quickly on the pedals you could flip backwards. There are hills in the Smokey and blue Ridge where no matter what gearing you have if you are fully loaded it is better to walk. I rode the Assuallt on Mitchel 5 times with very respectable times, with no luggage of course, and found that for a fast road bike with top notch gear equipment there is absoutely no need for a rear cog smaller than about 24-26 teeth with a 40-42 tooth cahinring [700 mm tyres].

If you are familiar with the Worlds' Most Traveled Man by Bicycle Heinz Stucke:

http://www.bikefriday.com/main.cfm?fuseaction=WhatDoYouDo.gallery&rider=StuckeHeinz

and

http://www.bikechina.com/ct-heinzstucke1z.html

Then you may be surprised that for nearly 35 years he only used a one speed or 3 speed. He said he enjoyed the break that walking gives him.

Of course it is nice to the get the best gearing that we can actually use but extremely low lows may not be too great.

My 2¢ and best to you!

Slim

It is true that an experienced ridr can stay upright all the way down to "stall speed" but it is much healthier to walk occasionally to break up long or difficult climbs.


Good point walking up hills are much better for your bones: they get stressed from walking and pushing that weight uphill. Thus they your brain will signal them to stiffen up.


I have toured with 50-75 Lbs of gear, self contained...

Do you tour with that much gear? It always amazes me that thru-hikers do the PCT (Pacific Crest Trail 2,600+ miles) with less than 20 lbs on thier backs, yet cyclists insist on touring with at least double that weight. I know tools and stuff are heavy, but crap. I mean if your covering a metric century a day, why haul all that wieght? You're bound to travel through some small town somwheres to resupply.

It just seams that toutists haven't adopted the ultralight thing.

I rode the Assuallt on Mitchel 5 times with very respectable times, with no luggage of course, and found that for a fast road bike with top notch gear equipment there is absoutely no need for a rear cog smaller than about 24-26 teeth with a 40-42 tooth cahinring [700 mm tyres].


This statement is meaningless here on the recumbent forum. A 40/26 gear on a wedgie would make for a 40 inch gear, and there is no way an average rider could do, say, a 15% grade in that gear while seated. In fact, I'd go so far as to venture a guess that few DF riders could do a mile or two of 8% without standing.

In that same situation, and without the possibility of standing, the bent rider would be presented with the choice: downshift or get off & walk. That's why bents generally have a low gear in the 25 inch range.