Extremely low gears

Cycle-touring, Expeditions, Adventures, Major cycle routes NOT LeJoG (see other special board)
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NUKe
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Re: Extremely low gears

Post by NUKe »

mattheus wrote: 29 Jul 2021, 3:55pm
NUKe wrote: 29 Jul 2021, 3:51pm A question how low is too low. there must be a point when you can either walk and push the bike quicker.
Why do you think this is the case? From there, you stand a chance of coming up with an actual number.

[as it happens, a large number of posts have discussed the speed at which this happens!]
It was a simple question. “As it happens”
At what speed or how small a gearing, do you say enough is enough and walk. Or you can’t balance anymore.
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Vorpal
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Re: Extremely low gears

Post by Vorpal »

For me, it varies. It varies with load on the bike, steepness of the hill, and things like whether I got enough sleep the night before, or it's getting near lunch time, or it's really hot out, or I want to stop and enjoy the view

I walked some parts of https://www.google.no/maps/dir/3580+Gei ... 126206!3e1 last year. The first section is gravel and a couple of bits would have been hard going on a MTB, let alone a loaded tourer. But I also wasn't touring fit, yet. 3 days later and I probably could have done all of it except the gravel section, without walking. I don't know if I would have. There is some beautiful scenery along there, and I stopped quite a lot to admire it, or walk a little off the road for a better view. I didn't always stop in places that were conducive to starting again.

Could I have ridden more of it with a lower gear? Probably. Is it worth changing my whole drive train to do so? Probably not.
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Mick F
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Re: Extremely low gears

Post by Mick F »

Sorry, late to the party here.

If you want a cheap and easy solution to gearing, fit a SA3p as well as your chosen derailleur gearing..
https://www.sturmey-archer.com/en/produ ... rf3-silver
https://www.sjscycles.co.uk/hubs-intern ... e-hub-36h/

I fitted one, as recommended on here.
Bottom gear now 15.6" and top is 123.7" :D

Triple 10sp x 3sp = 90
Mick F. Cornwall
djb
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Re: Extremely low gears

Post by djb »

Alik, my tourer is very similarly set up like yours, with 26 inch wheels, with a low of 16.7 gear inches with 2inch tires, which works great in very hilly terrain, in which i have toured a fair amount.

Could you provide info on the specifics of your bike, number of gears, rd rear derailleur and type of shifters?


Answers are necessary for proper suggestions.
Also, very important, how heavy is your bike loaded up. (Or simply, how heavy is your load)
How old are you, how much do you ride?

Ps check out this gearing calculator, change display to gear inches and you'll get g.i. for each gear
http://www.gear-calculator.com/?GR=DERS&KB=24
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Tigerbiten
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Re: Extremely low gears

Post by Tigerbiten »

djb wrote: 30 Jul 2021, 1:44pm Answers are necessary for proper suggestions.
Also, very important, how heavy is your bike loaded up. (Or simply, how heavy is your load)
How old are you, how much do you ride?
You missed one..
How high a top gear do you want.

A 1x setup with a 5x range can easily have a first gear of 17".
But that only gives you a top of only 85" meaning you'll spinout around 20 mph.
That fine for bouncing down off-road tracks, but a bit low for smooth downhill tarmac.
Doubles and triples are easy to build with a 6x range and the limits arounds 7.5x for a triple.
Pushing the limits can give you something like 14"-110", a very workable wide range for a touring bike.
Going for a wider range means going more exotic.
Add a SA IHG to the mix and it's easy to get a 10x range, so 13"-130" is doable if you want a high top gear to go with a very low first gear.
Using twin IHG, A Rohloff and a Schlumpf HSD, will give you a 13x range, so 11.5"-150" is doable if you want a very high top gear as well.
It's possible to go even wider, my bent trike has a 18x range, but it's very rare I need anywhere near that full range.

Luck ............. :D
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mjr
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Re: Extremely low gears

Post by mjr »

NUKe wrote: 29 Jul 2021, 11:05pm At what speed or how small a gearing, do you say enough is enough and walk. Or you can’t balance anymore.
I say enough is enough and walk if I need to go slower than my 40" gear. Then I get off and use my 24" gear ;)

But with touring luggage, I'm only doing 40ish miles a day, which is far far less than some of the heroic nobility on here. I even stop to visit things! :shock:
MJR, mostly pedalling 3-speed roadsters. KL+West Norfolk BUG incl social easy rides http://www.klwnbug.co.uk
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LittleGreyCat
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Re: Extremely low gears

Post by LittleGreyCat »

Interesting thread.

I'm not sure that I have seen it called out clearly; the main thing that stops you falling off a bike is the gyroscopic effect of the wheels rotating.
Once you get rolling the bike stabilises itself.
Edit 2: I assume that the smaller the wheel the faster RPM which could give more stability at very low speeds.

At very low speeds you lose almost all of this effect. You might be OK doing 2 mph on the flat on a well balanced bike, but you are more likely to be unstable on a fully loaded touring bike when trying to get your legs to spin round to keep moving and haul on the bars to give you some extra heft.

If you lose some leg spin, getting it back is tricky (especially if you are restarting after a stop) as your first few pedal strokes won't really move you very fast or very far.

Anyway, I had my Spa Wayfarer derated in anticipation of hill climbing (scuppered by Covid).
Rear 36 up from 34 and front down to 24 from 28.
So 44-34-24 front.
Was 48-38-28.
11/36 back.
Was 11/34.

I need to find the fine details of the rear cassette (never can remember) but I should have a bottom gear of just below 19".
Edit 1: Sheldon Brown says 108" down to 18".

All I need now is some leg strength, plus psychic ability to know when to "granny out" BEFORE the very steep bit as I find it hard to change down to the very lowest gears when the drive train in under extreme load.
LollyKat
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Re: Extremely low gears

Post by LollyKat »

A few weeks ago my husband and I were out for a hilly ride. He doesn't have the 20" gear that I have and was reduced to pushing a few times. With some effort I could stay in the saddle but was no faster than he was. I ended up walking as well - much more relaxing!
Tiggertoo
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Re: Extremely low gears

Post by Tiggertoo »

mattheus wrote: 29 Jul 2021, 5:05pm
Tiggertoo wrote: 29 Jul 2021, 4:13pm ...
the climbing speed is down to 4 MPH and the risk of falling off due to not being able to unclip from the Looks,
...
I never have a problem unclipping when stationary (or almost stationary). Is this a LOOKs problem? I've never ridden with them (leave 'em to you racey types! )

Probably. They are a bear to clip in, they spin so you have to look down to clip in and when you look up again there is often a huge lorry bearing down on you. Unclipping seems to be a problem when on an incline - or maybe it's just me stressing and trying to pull up rather than twisting sideways.
I've thought of converting to Speedplays, and two of my bikes do have SPD's but my favourite shoes have the Look cleats so I'd have to completely rework and buy new if I changed to anything else. Once rolling though, the Looks are very comfortable
cycle tramp
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Re: Extremely low gears

Post by cycle tramp »

LollyKat wrote: 30 Jul 2021, 9:06pm A few weeks ago my husband and I were out for a hilly ride. He doesn't have the 20" gear that I have and was reduced to pushing a few times. With some effort I could stay in the saddle but was no faster than he was. I ended up walking as well - much more relaxing!
+1 I have to admit that if I encounter a reasonably steep hill, I'll get off and push. I've done this during a few group rides and tours, and a couple of times I've either kept up with riders using their smallest gears and once overtook them by walking.
Having walked to the top of the hill, I find my cycling muscles have had a chance to recover.
It's time to go :-)
Tiggertoo
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Re: Extremely low gears

Post by Tiggertoo »

cycle tramp wrote: 30 Jul 2021, 11:02pm
LollyKat wrote: 30 Jul 2021, 9:06pm A few weeks ago my husband and I were out for a hilly ride. He doesn't have the 20" gear that I have and was reduced to pushing a few times. With some effort I could stay in the saddle but was no faster than he was. I ended up walking as well - much more relaxing!
+1 I have to admit that if I encounter a reasonably steep hill, I'll get off and push. I've done this during a few group rides and tours, and a couple of times I've either kept up with riders using their smallest gears and once overtook them by walking.
Having walked to the top of the hill, I find my cycling muscles have had a chance to recover.
Riding from Penzance to Plymouth the year before last, my quads were screaming at me on the hills, mostly due to lack of hydration and electrolytes. Walking the hills helps them to recover and allows me to drink more - which pulling hard on the bars to make the hills is not so easy.
djb
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Re: Extremely low gears

Post by djb »

Tigerbiten wrote: 30 Jul 2021, 3:11pm
djb wrote: 30 Jul 2021, 1:44pm Answers are necessary for proper suggestions.
Also, very important, how heavy is your bike loaded up. (Or simply, how heavy is your load)
How old are you, how much do you ride?
You missed one..
How high a top gear do you want.

A 1x setup with a 5x range can easily have a first gear of 17".
But that only gives you a top of only 85" meaning you'll spinout around 20 mph.
That fine for bouncing down off-road tracks, but a bit low for smooth downhill tarmac.
My bike has 16.7-104 g.i. which I spin out to a bit over 50kph or 30mph, which is ok by me as I'm fine prioritising the lower gears and freewheeling past 50k when I can.
Jdsk
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Re: Extremely low gears

Post by Jdsk »

LittleGreyCat wrote: 30 Jul 2021, 8:15pmI'm not sure that I have seen it called out clearly; the main thing that stops you falling off a bike is the gyroscopic effect of the wheels rotating.
Once you get rolling the bike stabilises itself.
Gyroscopic effect doesn't hold a bike up by itself, and I doubt if it's ever the "main thing" for real bikes on real roads.

It does affect control by steering.

The best description of the physics that I know is in Bicycling Science. But there's an article here that has a go with some simulated data:
https://goodbicyclescience.com/2016/04/ ... effect-do/
(I'm not familiar with JBike.)

Jonathan
djb
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Re: Extremely low gears

Post by djb »

Re balance and low gearing, for short periods I've climbed regularly at 5kph seated, countless hours at 7, 8 kph.
So slow climbing with a 17g.i. loaded is both handy and doable, you just have to practice, it's not that hard.
djb
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Re: Extremely low gears

Post by djb »

Vorpal wrote: 30 Jul 2021, 9:07am For me, it varies. It varies with load on the bike, steepness of the hill, and things like whether I got enough sleep the night before, or it's getting near lunch time, or it's really hot out, or I want to stop and enjoy the view

I walked some parts of https://www.google.no/maps/dir/3580+Gei ... 126206!3e1 last year. The first section is gravel and a couple of bits would have been hard going on a MTB, let alone a loaded tourer. But I also wasn't touring fit, yet. 3 days later and I probably could have done all of it except the gravel section, without walking. I don't know if I would have. There is some beautiful scenery along there, and I stopped quite a lot to admire it, or walk a little off the road for a better view. I didn't always stop in places that were conducive to starting again.

Could I have ridden more of it with a lower gear? Probably. Is it worth changing my whole drive train to do so? Probably not.
All good points re how tired you are, although I really prefer riding than pushing, especially if it's steep I find riding easier, plus you don't hit your shins on pedals.

If the surface is too loose this gets tricky, and comes down to tires and tire width.
I'm a big fan of larger tires, and chose my tough tourer predominantly because out can take up to 2.5 inch tires, wider a bit at front but I'd need wider rims.

My 16/17 to 104 gear inch setup is ideal for me touring, and I can always change to a smaller cassette if I really don't need the lower stuff and have tighter shifts.
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