An unfashionable gearing set up?

[steveha]

I've been looking to replace an ancient touring bike with 2x5 gears and have looked at 1x11 systems but I've had another idea for a 2x10 that doesn't seem to be off the peg.
But first, the situation and what I'm trying to achieve

• Live an a hilly area so want a wide range of gears
• Gradients change quite often so I want to get in roughly the right gear quickly
• Occasionally ride in flatter areas and want exactly the right gear

So here's the plan:

So the logic is:

1. Most of the time, I can go up and down the cassette without worrying about which chainring I'm on
2. When I want to fine tune the ratio - typically in the middle of the range (EG: I'm on 66" and fancy 63")
   • Change down to 59"
   • Change chainring to get 63"

Comments? ;-)

 

[Sharky]

At the extreme ends, you will be using big/big and small/small combinations, which may not run smoothly.
What is the width of the old hub, which is presumably a screw on 5 speed block? To get an 10 speed cassette, you will need a new wheel, which will be wider and won't fit the rear fork ends?

Good luck with the project.

 

[Reynard]

Can't say much about hills because I'm out in the fens where it is, well, flat... But if you do intend riding that particular set-up on the flat, that 42T big ring is probably going to be far too small.

Why not look at a triple up front instead? That's even more versatile. Spa Cycles do a nice 48-38-28 touring triple. And they can do custom chainsets as well.

 

[Flying Dodo]

At the extreme ends, you will be using big/big and small/small combinations, which may not run smoothly.
What is the width of the old hub, which is presumably a screw on 5 speed block? To get an 10 speed cassette, you will need a new wheel, which will be wider and won't fit the rear fork ends?

Good luck with the project.

Generally, the OP's bike should be possible to take anything up to & including a new 7 speed freewheel without having to worry about spacing. Shimano TZ500 14-34 is dirt cheap. Definitely need a bigger big ring though.

 

[Tigerbiten]

What the OP is trying to set up is called a half-step setup.
If the cassette has around 15% steps then the chainrings have half that or around 7%.
Normally it was set up as a half-step and granny triple, steps of 7% and 33% between chainrings.
I had a setup like that around 40 years ago.
You could get a wider range for touring with that setup while keeping close spaced gears rather than with just a plain corncob cassette.

Luck ..........

 

[si_c]

As @Tigerbiten says this is basically half-step gearing and something that was very common for touring bikes as it gave you a system with small gaps between the gear ratios with a limited number of overall number of sprockets at the rear.

I doubt the OP would be easily able to get that specific spacing of cassette - I've had a quick look and couldn't find anything. My suggestion would be to look at an 11 speed drivetrain with a sub-compact 46/30 chainset and an 11-34 cassette. This would give much better overall spread of gears using readily available parts and still give small steps between gears at the lower end of the cassette. This is what I'm thinking.

 

[steveha]

At the extreme ends, you will be using big/big and small/small combinations, which may not run smoothly.

Those I've marked in grey. I don't think I'll miss the 27" but I might be tempted to use the 88" :-)

What is the width of the old hub, which is presumably a screw on 5 speed block? To get an 10 speed cassette, you will need a new wheel

I'm actually going for a new bike :-)
Thanks!

 

[steveha]

I doubt the OP would be easily able to get that specific spacing of cassette - I've had a quick look and couldn't find anything.

Fair point. Here's something close that seems to be available

Front Small	Front Large	Rear Teeth	Inches S	Inches L	step up %
39​	42​	42​	25​	27​
39​	42​	37​	28​	31​	14%​
39​	42​	32​	33​	35​	16%​
39​	42​	28​	38​	41​	14%​
39​	42​	24​	44​	47​	17%​
39​	42​	21​	50​	54​	14%​
39​	42​	18​	59​	63​	17%​
39​	42​	15​	70​	76​	20%​
39​	42​	13​	81​	87​	15%​
39​	42​	11​	96​	103​	18%​

 

[SkipdiverJohn]

Not really sure I see much benefit to such an arrangement, as using the gear ratios sequentially would involve endless tedious double-changes. I much prefer to only have to shift one gear lever at a time, especially as my drop bar bikes both use downtube friction shifters and I don't want to be endlessly fiddling around with both the left and right hand one.

 

[Pale Rider]

Oddly enough a 6 speed Brompton is similar to a half-step setup.

Thanks for this - I now grasp what 'half step' gearing means.

Not that I can see any point in it, particularly for a leisure cyclist.

Just buy a Rohloff bike and twist the shifter until you get the gear you want.

Roadie Rohloffs are not common, not least because you have to fit a third party shifter for drop bars.

But Shand make a few.

https://www.shandcycles.com/bikes/

 

[Sharky]

If you are looking for basically a 1 tooth difference at the rear (straight thru cassette), try exploring "junior cassettes"
Sizing Information
Gear Ratio:

• 14/15/16/17/18/19/20/21/23/25
• 16/17/18/19/20/21/22/23/24/25

Then just choose the chain rings to give the max/min ratios you need.
A triple with a 16-25, could be the ideal solution.

 

[Tigerbiten]

One trouble I can see is getting a front derailleur that will work well with both the small chainring sizes and difference.

I'd be more inclined to go for a 11-28 10 speed and match it up with something like a 40-26 alpine double.
That will give you your 100"-25" range, close spaced at the top end but getting wider when you get down to the hill gears.
The only real downside is the 3-4 sprocket shift when you shift the chainring.

Luck ..........

 

[steveha]

In practice you probably don't care about strict sequencing but just want to get to the correct gear, so you use the right hand as a coarse adjustment and add the left as a fine-tune option as required.

Interesting reading: https://sheldonbrown.com/gear-theory.html

Exactly! :-) Thanks for the link to Sheldon Brown :-)

 

[Blue Hills]

Interesting reading: https://sheldonbrown.com/gear-theory.html

Thanks for that - as always an awful lot of common sense/demystification from the great Sheldon.

 

[GuyBoden]

If it's an old 5 speed touring bike and you want to get uphills easier a front triple is a good answer.

If currently it is currently a rear 5 speed, the max you could possibly get is a rear 7 speed, without having to spread the rear stays.

So, I recommend a front triple and a rear 7 speed.