Limablu2

Recently bought a vintage (2001-ish) 8sp bike that I plan to use for touring. The triple crankset 52-42-30 and the 11-32t cassette gives me a decent gear inch range 25-128, however I plan to travel loaded in very hilly terrain so I’d, like to bring the lower range closer to 22 inches.


Need advice please (or validation that these options are feasible) with what would work best with my 8sp Sora brifters, Sora front derailleur and wide range Deore rear derailleur combo. Each of the following would give me a 22 gear inches:

1. Swap the crankset for a 48-38-26 model

2. Swap the 30t chainring for a 28t (exceeds the theoretical 22t differential) AND swap the cassette for a 11-34t

3. Swap the 30t chainring for a 26t. Is this even possible?

xroadcharlie

I like the 48/38/26T chainring option best of the 3 you have listed as It maintains the 22T difference of your current chainrings while reducing cranking effort by about 13%. You'll still have 118 gear inches on tap for the highest gear. You'll Probably seldom even use the 48/13 cogs, which is still nearly 100 gear inches.

This is a popular option for many manufacturers so it should be quite reliable. That is very important for touring. Should be easy to get parts for too in the event you need them.

That said, 22 gear inches may not be low enough for the challenging, long hills. I'd try the bike as is first, loaded to get an idea if the 22 is sufficient. You might need closer to mountain bike gearing for steep hills with a load. The 22/32/44 is a popular option for an 18 - 108 gear inch range.

I'd just like to avoid using the 11T cog because the next step to 13T is much too big in the highest ranges. But you still might not need it even with these chainrings as 44/13 still provides 91 gear inches for 32+ kph at a leisurely 75 rpm.

Andrew R Stewart 

Most riders who have not toured with a load don't understand (haven't experienced) what riding up a 4 hour hill is like, at 3 or 4 MPH. I have suggested many times that on a touring bike one should have a 3mph gear, that there's no such thing as a too low a gear but there's way too high gears all the time.

Get the lowest gear your bike can fit. Andy

TPL

Andrew R Stewart <= his response makes a lot of sense

cyccommute 

To begin, the changes you propose will work with minimal equipment replacement. The Sora front derailer is a better choice than it’s more expensive cousins. It’s more forgiving over a wider range. The only adjustment you might have to make is to the bottom bracket width because the crank you propose to use sits a wide wider than a road crank and your front shifter may not have enough range to cover that. That’s not something that is difficult to change. Narrowing the bottom bracket 2 to 3mm narrower will do the trick as long as the chainring don’t hit the chainstay.

This is probably the better option. This gear chart shows the differences between your current set up and the new one. The 129 gear inch high on the 52/11 combination is mostly useless. Seldom are you going to run across a situation where you really need a gear that tall. The 119” gear that 48/11 combination gives is still rather high.

About the chain wrap, you should consider it more of a suggestion than a hard limit. I’m way past the limits and suffer no ill effects. I’m currently running a 44/34/20 which is a 24 tooth differential but I’ve run 48/36/20 cranks in the past which is a 28 tooth differential without suffering from poor shifting. Here’s the gear chart for those combinations

It depends what the inner bolt circle diameter (BCD) is. If it is 74, you should be able to use a 24 tooth inner. If you went that route, I’d suggest getting a 39 tooth middle ring, however. It would shift a little better. Here’s the gear chart for the 26 tooth inner and here’s the gear chart for the 24 tooth inner.

I would propose something entirely different, however. Go to the 44/34/22 gearing of a mountain bike triple. Here’s the chart. You reduce the high to 109” which is still a pretty good high gear. It’s higher than old school road bikes which had 52/14 101” gears. You get lower gear without too much trouble as well. Used mountain bike triples are a dime a dozen. You could even pick up an external bearing crank which are easier to install and a bit more robust than square taper for not too much. With a little bit of surgery, you can even get down into stupidly low gears by replacing the 22 with a 20 (with a 34 tooth cassettes, that 16” gear).

Don’t be afraid to experiment. You won’t break anything if it doesn’t work. It just won’t work. Don’t be afraid to think outside the box.

HillRider

Assuming a 74mm bcd for the granny ring, this is very possible and I've done it on numerous cranks. My two current Shimano FC-5703 cranksets have been altered from 50/39/30 to 50/39/26 and shift well. The shift from the 39 to the 26 goes well. The shift back from the 30 to either the 39 or 50 is a bit sluggish but you are rarely in a rush for that one. Yes, you exceed the recommended chainring tooth difference and probably exceed the rear derailleur's wrap capacity but avoid small-small and you will be fine.

In the past I've done this 30T to 26T granny chainring swap on older 52/42/X Shimano cranks and even a 53/42/X Campagnolo crank and both worked fine.

FastJake

Assuming you have a 74 B.C.D. for the small ring, replace it with a 24T. Remove the silly 52T ring which you will never, ever need. Unless you plan to pedal your loaded touring bike downhill at 40MPH for some reason. Replace the cassette with an 11-34. And you're done, unless you still need lower gears than that.

Summary: 24/42 using your current crank, 11-34 cassette.

Limablu2

Many thanks for all the help! A couple of new options!! I like the idea of the 44-32-22 crank. I see a couple of them on ebay. The 24T/26T granny (yes it's a 74mm BCD) could be easy and cheap to try too.

davidad

A 24-34 gear will be about 19 inches and give you a speed of 3.7mph at 65 rpm crank speed.

Andrew R Stewart 

24x34 had been my low gear for quite a while, with a 622-32 tire. My current tour set up has 559-38 tires with a 24x36 low gear.

I've found it's not about having the power to push a less low gear but it's the motivation and connective tissues that are lacking for me. Andy

kek

48-38-26 and 44-32-22 are mtb cranksets
road cranksets/fd and mtb cranksets/fd have different chainline
road frontshifters/fd and mtb frontshifters/fd have different cable pull

you can find these topics on forum:
using Road front derailleur on MTB crankset
Mixing road shifters and derailleurs with MTB crankset
FD compatible with MTB shifters and road triple cranks?
Using Mountain Bike Crank and Front Derailleur on Road Bike
etc