Importance of gearing range

[dimrub]

Well, here's the patient (sorry about the dirt. I'll wash and lube it today, promise):

So it's a 5-arm assembly, and it seems this guy over here is a suitable replacement (the photo says 50T, but they have them all the way down to 38). Seems right? And I don't need anything aside from allen key, and I guess I don't even need to remove the crank, right?

 

[All uphill]

Well, here's the patient (sorry about the dirt. I'll wash and lube it today, promise):

View attachment 703440

So it's a 5-arm assembly, and it seems this guy over here is a suitable replacement (the photo says 50T, but they have them all the way down to 38). Seems right? And I don't need anything aside from allen key, and I guess I don't even need to remove the crank, right?

You'll probably need to shorten the chain, so a chain tool is essential too.

 

[dimrub]

You'll probably need to shorten the chain, so a chain tool is essential too.

Oh. I thought chain tensioner will take care of that. Ok then.

 

[All uphill]

Your chain goes round half of the chain wheel.

50/2 =25

If you change to a 40 tooth chainwheel the chain will go around

40/2 = 20

a difference of 5 links.

You'll feel like you have a new bike! As others have said it makes a huge difference just knowing you have those low gears for when you need them.

My tourer's lowest is 30/40, somewhere around 20 inches and it gets used!

 

[Spiderweb]

You’ll need to shorten the chain.
If it were my bike I’d bag up the old chain & chainring and keep for if you ever want to swap back.
Buy a new chain for the new chainring.

 

[roubaixtuesday]

Your chain goes round half of the chain wheel.

50/2 =25

If you change to a 40 tooth chainwheel the chain will go around

40/2 = 20

a difference of 5 links.

You'll feel like you have a new bike! As others have said it makes a huge difference just knowing you have those low gears for when you need them.

My tourer's lowest is 30/40, somewhere around 20 inches and it gets used!

If I've read it right @dimrub is only downsizing from 42 to 38, not 50 to 40.

That's only 4 teeth, and as you say, only half contact the chain.

But there's also two teeth per chain link, so only one link shorter.

Probably same length chain would be fine.

 

[Spiderweb]

If I've read it right @dimrub is only downsizing from 42 to 38, not 50 to 40.

That's only 4 teeth, and as you say, only half contact the chain.

But there's also two teeth per chain link, so only one link shorter.

Probably same length chain would be fine.

Ah yes, I’ve read the OP’s post wrongly so ignor my contribution.
Current chain will be fine.

 

[presta]

This is what I use for fully laden touring on gradients up to 1 in 3:

I'd rather be freewheeling downhill because top isn't high enough than pushing uphill because bottom isn't low enough.

 

[dimrub]

This is what I use for fully laden touring on gradients up to 1 in 3:

View attachment 703452

I'd rather be freewheeling downhill because top isn't high enough than pushing uphill because bottom isn't low enough.

Wow, that's an impressive gear range. That's a grandmother of all granny gears right there.

So, I went ahead and ordered me a chainring. Also ordered an Ortlieb branded cable for their fecking handlebar bag, because I always do (I mean, how did they not figure out that people may want to remove the fitting, then remount it - is beyond me). At least they now sell the cable separately, not making me buy the whole damn fitting.

 

[GuyBoden]

My lowest geared touring bike has a triple 24-34-44 and rear sprockets 11-42t.

I've just built a fat old bloke hill climber with a single 30t front and 12-46t rear sprockets, it rides up 20%+ very slowly, but very easily.

 

[Jameshow]

This is what I use for fully laden touring on gradients up to 1 in 3:

View attachment 703452

I'd rather be freewheeling downhill because top isn't high enough than pushing uphill because bottom isn't low enough.

I freewheel above 20mph when touring!
Lift off the saddle too.

 

[sleuthey]

Aside from it being "38T narrow-wide" and the mounting method?

BCD (Bolt Centre Diameter) needs to be the same.

 

[HobbesOnTour]

I'm just not sure I want to risk the whole trip on something going wrong with the bicycle, or with my fit to the bicycle

I did italicise reputable
For the right bike, and one I expected to serve me for a long time I wouldn't have an issue.
I wouldn't head off on a months long tour on it from the get go, though.

Reassuringly expensive.

There's a certain relativity to these things. I recall doing some sums a few years ago and given the savings offered on plane travel it made sense after a surprisingly (to me) small number of flights.
Such a method of transport also opens up more flexible options of public transport, especially for those who pack more minimalisticaly.

In my case it didn't seem to make a lot of sense for a €200 bike that was likely to be overweight anyway and given my propensity to carry a lot of gear not such a huge advantage.

I did witness one "in the wild" so to speak and was quite impressed. A couple, his S&S in a hard case seemed to have had a safer trip than hers - a standard cardboard bike box that had received quite a battering. A certain amount of that reassuring expense pays for the peace of mind of safer transport.

The case can represent an issue for storage while touring and a bigger one for end to end type tours, though.

 

[presta]

Wow, that's an impressive gear range.

It was nothing special in 2007 when I upgraded my Horizon, just standard Shimano Deore, but I'm not sure it's even possible now unless you can find some old obsolete stock.

 

[roubaixtuesday]

It was nothing special in 2007 when I upgraded my Horizon, just standard Shimano Deore, but I'm not sure it's even possible now unless you can find some old obsolete stock.

We run 24/36/46 and 11-36 with current Sora (9 speed).

It's marginally outside the nominal range for both largest sprocket and total RD capacity but works perfectly.