How low can you go? Gears.

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LittleGreyCat
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How low can you go? Gears.

Postby LittleGreyCat » 14 Dec 2019, 6:37pm

I have noted that my newish Spa Wayfarer has what 531colin describes as "young mans gears".
So I have resolved that at some point before my planned JOGLE I will lower the gearing.
Current gearing 28/38/48 and 11/34.

https://forum.cyclinguk.org/viewtopic.php?p=1408092#p1408092 has a post saying
How low do your gears go on your bike ??
The lower your gears are, the easier it is to lug the extra few Kgs of camping gear up the last hill before the campsite.
A lot of touring bikes have a first gear around the 25" range for this reason.


Using https://ritzelrechner.de/?GR=DERS&KB=48,52&RZ=13,14,15,16,17,18,19&UF=2150&TF=100&SL=1.7&UN=MPH&DV=gearInches&GR2=DERS&KB2=42,52&RZ2=13,14,15,16,17,19,21&UF2=2150 suitably modified I seem to have a lowest gear of 22.9 gear inches. So already below the suggested 25". Highest is 108".

If I remember correctly, 531colin said that he rode 20/30/40 on the front.
That would give me (with my 11/34 on the back) a range from 101" top to 16.4".
Or a speed (at a cadence of 80) of 3.9 to 24.1 mph bottom to top.

Looking around, https://www.cycletourer.co.uk/cycletouring/gears.shtml suggest that for heavily loaded touring you have a top of 100" and a bottom of 18". So my proposed 20/30/40 is not far off that but slightly lower at the bottom.

So it does look as though changing the front to 20/30/40 would give me a set of gears more suitable for heavy touring (or a flat lander encountering long steep hills).

It does beg the question, though, of how low you can go and still have a rideable bike.
What is the lowest gearing where you could expect to stay on the bike (gyroscopic action of the wheels) when climbing an extreme 1 in 4/25% gradient?
I suspect that the difference between 22.9" and 16.4" isn't going to save me when the going gets tough, but it might get me up some slightly lesser gradients without having to climb off.
I was also advised that dropping the 28 to a 24 (or perhaps even a 22) and leaving the rest alone might be a simpler way to get the lowest gears.
That would give me a lowest gear of 18" or 19.3".

Anyway, I am having trouble visualising how low I should realistically go, and how much difference changes will make.
I could do something extreme like having a largest rear cog of 48 teeth which with a 20 tooth front would give me 13.9" or a speed of 3.31 mph with my legs doing 80 rpm but the changes don't seem massively significant in real world terms.

My aim, obviously, is not to have to replace the rear derailleur and gear cluster plus the front mech and gears because that could be quite expensive.
On the other hand I don't want to make the trip of a lifetime one long misery in the mountains.

I know that "ride more hills" is one answer, but there aren't very many here and certainly no long ones.

fastpedaller
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Re: How low can you go? Gears.

Postby fastpedaller » 14 Dec 2019, 6:47pm

I'd aim to make lowest RPM about 65, given that if the hill is very steep the rider will be out of the saddle and 80rpm is unlikely to be attained. Also at 3mph (I've been there :( ) there's very little opportunity to ride in the saddle and keep the bike steady - a quick exit is sometimes needed :lol:

PH
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Re: How low can you go? Gears.

Postby PH » 14 Dec 2019, 6:53pm

LittleGreyCat wrote:On the other hand I don't want to make the trip of a lifetime one long misery in the mountains.

On a general point, whatever gears you feel you want, my touring bikes have lowest gears of 20 and 23" and occasionally I'll get off and walk. I so rarely use anything over 95" that I wouldn't miss it. What I wouldn't want to do is compromise those gears I use most for small advantage at either end.
On the specific point quoted above - you won't. It would be poor planning if you ended up on a mountainous route, on my 1,100 route I doubt more than 50 miles was in the smallest ring. I'm not saying you shouldn't plan for those miles, but they won't dominate the trip.

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Paulatic
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Re: How low can you go? Gears.

Postby Paulatic » 14 Dec 2019, 6:55pm

16.5 " if that doesn’t get you up a hill nothing will.
101” might well be enough for a top gear but if your bike handles well with a load you might want to keep 48 as a big ring to keep those long descents rolling.
Touring earlier this year with full camping kit, on a bike which was never designed for carrying a load, I discovered where my brake levers are every time I hit 30 mph.
Whatever I am, wherever I am, this is me. This is my life

https://stcleve.wordpress.com/category/lejog/

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531colin
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Re: How low can you go? Gears.

Postby 531colin » 14 Dec 2019, 6:58pm

Your chainset has bolt circle diameters of 110 and 74mm.
The smallest chainring you can fit is 24T on the 74mm BCD.
The smallest chainring on 110mm BCD is 34T.
I run 24/34/46 because my front mech. wants a 12T difference between middle and top; I guess your front mech. wants 10t difference.
So, the cheapest thing is to swap your 28 for a 24, and see how you get on.
Its quite a lot more money to swap the 38 for a 34, and the 48 for a 44; these swaps won't make much difference to your gear range, its only worth doing if you find a 24/38 gearchange too big a change for either your legs or the front mech.

tatanab
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Re: How low can you go? Gears.

Postby tatanab » 14 Dec 2019, 7:01pm

LittleGreyCat wrote:Looking around, https://www.cycletourer.co.uk/cycletouring/gears.shtml suggest that for heavily loaded touring you have a top of 100"
Even in my youthful racing days, 40 plus years ago, I never geared that high. I suspect the reason people like to do it these days is because they have 10 at the back not the 5 of years gone by.

My touring gearing for cycle camping with an all up weight of 65lbs (machine and luggage) is 46/36/24 with 13-28 on a triple or 40/24 with 12/28 on a double. Bottom gear is about 23". I usually use the double for touring so have a top gear about 90", much above 35mph I am likely to be freewheeling. That gear will get me over the Pyrenees and similar mountains with no problem; I don't know about anything much longer or steeper. Equally, as noted by others, my cadence drops off when climbing. 80-100 is my rate on the flat but I doubt I get above 60 when climbing.

Each to their own with bigger or smaller gears, so to your question of how low can you go. About 30 years ago I met a chap who had a bottom gear of 11" which I thought would be unrideable. He told me he had proved to himself many time over that it is easier to ride very very slowly than it is to push a bike in his preferred touring country of the deserts of the world.

Jamesh
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Re: How low can you go? Gears.

Postby Jamesh » 14 Dec 2019, 7:05pm

Unless your keen to bag a few climbs on your jogle then 28/34 would be more than adequate.

I rode audax style on a 50/34 X 11/36 and don't think I used the 36 or 32t on the cassette.

I often find that when I put go into a granny gear my legs are already shot from the early part of the climb to really spin the granny gear......


Cheers James

LittleGreyCat
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Re: How low can you go? Gears.

Postby LittleGreyCat » 14 Dec 2019, 7:29pm

Thanks to all for the responses.

I will start by trying a smaller front ring - 28 to 24 - and see if I can find a few hills to try this out on.

There is a bit of "you will be standing on the pedals" and my current riding style only has me up out of the saddle just before it all goes horribly wrong.
I think that it is Chris Froome who just sits down and spins steadily up mountains.
That is my preferred approach at the moment.
I have seen TDF riders standing up on the pedals and pulling a much higher gear at a low cadence; perhaps I should try that but my legs don't like it so far.

With regards to the route, I will be taking the longer East Coast minimum climb route.
I remain a little sceptical where people say that they almost never go into the granny.
Mainly because I ride in a group, and I go low to granny on quite a few hills but another rider says that since he moved to Suffolk he has never used the smallest front cog.
So I think a lot depends on how your legs work! :D

PH
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Re: How low can you go? Gears.

Postby PH » 14 Dec 2019, 7:57pm

LittleGreyCat wrote:I remain a little sceptical where people say that they almost never go into the granny.

Fair point, we are all different.
Regardless of gearing, I'd still say don't overestimate how long and hard the tough bits are.

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Tigerbiten
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Re: How low can you go? Gears.

Postby Tigerbiten » 14 Dec 2019, 9:20pm

If you want to check if you can shrink the inner chainring safely just measure the gap gap between the chain and the bottom of the front derailleur cage.
The chain will move down 2mm for every tooth lost.
Where as it vital that you can run big-big just in case you shift into it by mistake, if you cannot and you do things will go bang.
It's not so vital that you can run small-small without the chain rubbing on itself or going slack as nothing will get damaged short term if you do.

The other thing to watchout for with very low gears is torque/traction.
As the gears get lower then the easier it is to lift the front wheel.
So if the gears get low enough then it's easily possible to pull a wheelie going uphill.
Then you need to lean forward to increase the weight on the front wheel and keep it down on the road.
But this reduces the weight on the back wheel and you risk the back wheel slipping/spinning when you overtorque it and lose traction if the tarmac is wet/greasy/loose with gravel/etc.
So depending on the all up weight of the rider plus bike and the balance of the weight between the wheels then riding uphill in an ultra low gear may not be only a side to side balancing act.

YMMV .............. :D

whoof
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Re: How low can you go? Gears.

Postby whoof » 14 Dec 2019, 9:28pm

PH wrote:
LittleGreyCat wrote:I remain a little sceptical where people say that they almost never go into the granny.

Fair point, we are all different. .

Whenever any such topic comes up people can only ever say what gearing and cadence suits them. Some are churners some spinners and everyone has different strength and fitness.
For me bottom gear for touring with camping and cooking gear is about 20".
If I am touring and staying in b&bs then about 30" in addition to less luggage this would also be on 10 rather than 15kg bike.

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cycleruk
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Re: How low can you go? Gears.

Postby cycleruk » 14 Dec 2019, 9:47pm

I find it very awkward to stand and pedal when on very small gears. Plus it takes more out of you when standing then when sitting. I would try the 24T granny ring and see if that suits.
You'll never know if you don't try it.

PH
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Re: How low can you go? Gears.

Postby PH » 14 Dec 2019, 10:39pm

whoof wrote:
PH wrote:
LittleGreyCat wrote:I remain a little sceptical where people say that they almost never go into the granny.

Fair point, we are all different. .

Whenever any such topic comes up people can only ever say what gearing and cadence suits them. Some are churners some spinners and everyone has different strength and fitness.

All that is true, but not really the point I was making.
A 10T drop from middle to bottom on a triple is two lower gears. I'm saying don't over estimate how much of an E2E you're going to spend in your two lowest gears, whatever they may be.

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foxyrider
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Re: How low can you go? Gears.

Postby foxyrider » 14 Dec 2019, 11:05pm

LittleGreyCat wrote:I remain a little sceptical where people say that they almost never go into the granny.


i did a tour several years back - well 2015 actually, and used the smallest chainring twice, each time to ride up the ramp to board the Nort Sea ferry. Oh, i should mention i had full camping gear and a 50/34 running 12-29 at the back. My other touring steed has a low gear of 19", it has gone years sometimes without engaging the granny in anger, thats not to say its never been used but only rarely on 20% plus long Alpine climbs. Don't over think it, you may well be fine on the 'standard' set up.

As for sitting/standing - well there is a gradient, @ 10%, where sitting starts to have negative problems both with balance and keeping the front on the ground, at that point standing will often be better. One other thing to consider, will the parts allow changing into the granny on the climb or do you need to preselect and waste energy spinning like a top before the steep bit actually needs it? One last thing - whilst it might be nice to ride non stop up everything, there is no shame in stopping or even walking if neccesary.
Convention? what's that then?
Airnimal Chameleon touring, Orbit Pro hack, Orbit Photon audax, Focus Mares AX tour, Peugeot Carbon sportive, Owen Blower vintage race - all running Tulio's finest!

drossall
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Re: How low can you go? Gears.

Postby drossall » 15 Dec 2019, 12:18am

In the club I first joined, the story was that the then timekeeper (this was in the days of five-speed derailleurs) had welded a 13 sprocket to his chainset to get properly low gears. I never saw it, so cannot verify this story :lol: