5kdad

I've ridden a road and mountain bike for years. Have done a few loaded tours, on my mountain bike. I'm thinking about buying a touring bike. Was reading about one cyclist who had a 42/28 chainring combination, but said, if riding in more mountainous areas, would opt for a 24T. I live in the hills of Arkansas, and if I do a tour, would be riding some in mountainous regions. Plus, I'm overweight, and need the lower gear range. My question, if I bought a bike with 42/28 range, and wanted to swap out the 28T for a 24T, would I also need something smaller than the 42T, so as to maintain smooth shifting? Or would a 42/24 gear range still be ok?

robow

I've climbed your Mt. Magazine, Mt. Nebo, and Mt. Petit Jean fully loaded but somewhat light and believe me, even in decent shape I was forced to sink to my granny 24x34t and I weigh in at 170 when fit. You didn't state your cassette, but in other words, if I lived where you might ride, I wouldn't hesitate to have a 22t little ring.

ploeg

It depends on the capacities of your derailleurs. For a front derailleur, capacity is the maximum difference between your big and small big ring. For a rear derailleur, capacity is the maximum sum of the differences between your big and small ring and your big and small cog. Typically component makers will be conservative with their capacity specs, but if you go outside of that, you should ask your LBS about your proposed setup to see what they've been able to make happen (and then pay them to make it so). I don't have any experience with double mountain-type setups, but my understanding is that doubles are somewhat less tolerant of large chainring differences than triples are. Triples have that intermediate ring, which makes things a little easier on the derailleur.

ploeg

You might also want to take a look at this. Mixing up your gear can get you some good results, though you will probably want to consult an expert before pulling the trigger.

Low Gear Range: Road Shifters & Gears For Easier Hill Climbing - CyclingAbout

bradtx

5kdad, This thread: https://www.bikeforums.net/touring/10...ity-check.html has a pretty good range using a double crank set. It does limit top end, however.

Brad

shelbyfv

I think a triple would be good for your application.

BigAura

+1 to low mountain-double, if you're adamant about a double. The Deore FC-M617 38-24t, as suggested by @bradtx, would be a good choice. But a triple would give you a nicer top-end for those occasions when wind, down-hill, and/or mood, are motivating a speed increase.

nun

You don't mention the rear cassette. You need to consider both the front ring and the rear cassette when making gear choices.

I've found that the easiest way to change my gearing is to tackle the rear cassette. I bought a bike with 50/34 x 11/28 gearing and it was pretty easy to change it to 48/34 x 11/36 and get a low gear of 25" by installing a SRAM mountain bike rear derailleur and cassette.

Tourist in MSN

I used to use a road triple with an aftermarket 24T granny gear (52/42/24) on my derailleur touring bikes. First photo shows that range of gearing.

A few years ago for touring I changed the big ring down to 46 so my triple now is 46/42/24, which is half step gearing between the middle and big rings. Second and third photos show that setup.

Other components that are common to both setups are 11/32 eight speed cassette, XT M739 long cage rear derailleur, vintage Suntour front derailleur that was designed for use on a double, a chain catcher, and bar end shifters (BS64) that are indexed rear and friction front.

I often have to overshift a bit when I upshift from the 24 to 42, then back off after the shift is completed. That is a big jump, but it works well for me and I like the gear ratios so I don't change to something else. The downshift from the 42 to 24 is effortless and consistently works great. I do not know if the chain catcher is necessary, but it might help. Note that I am using a friction front shifter. So, the slight overshift is not any problem for me but if I had a indexed shifter, that might be a problem.

If you use a double like you are proposing, it probably will work better than on my triple because my front derailleur has to be up higher on the seattube for my big ring that is larger than what you propose for a big ring on a double.

5kdad

Wow, that's some serious climbing! I did a MS150 ride several years ago, that started on top of Petit Jean. First day, loop north then back to beginning. Second day, loop south. I was on my road bike, and I hitched a ride back up the mountain!
I'm looking at buying a touring bike (have a road and mountain bike, and recumbent trike). Trying to decide on gearing.

niknak

I haven't ridden a triple in years. For touring, or any type of riding, I don't see a need. Bigger riders or riders that carry big loads may see an advantage to having higher gearing for the flats, where their mass increases cruising speeds.

A 40/24T crank combined with an 11-34T cassette gets me over anything. A Sugino triple crank with 100/74 BCD allows pretty much any double chainring combo you can dream of, just don't go beyond a 16T difference between rings and you should be fine.

fietsbob

You are essentially proposing a triple , just without a Big chainring.. fill the gap with a chain guard if you want.

a single ring with a Bail out granny gear may make you happy..

I ran a 50-40-24 driple on tours for decades, but I didnt have the 11t cassettes, BITD, 50:13 was high enough..





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linus

46/30 Super Compact. Combine that with 11-40T cassette.

Squeezebox

I have a Sram crankset with 42-28. Just for the heck of it I asked the LBS about different chainrings. The only thing available is 26-38. For me not enough difference to mess with. The 28-36 puts me at around 21 or 22 in gear. That's pretty low. I'm okay with that so far. It could turn into a lot to mess with to get the 24 on and working. The overshifting that MSN mentioned on a triple is why I don't have one, or bar ends either.

HTupolev

That's an issue with shifting between chainrings of massively different size (24T and 42T), not triples.

Most modern triples are for multi-range gearing. The evenly-sized "small" steps actually make for cleaner front shifting than a double that's also trying to achieve good total range.

Bar-end friction front shifters allow you to operate drivetrains that need overshifting, but the use of a bar-end doesn't cause a drivetrain that otherwise wouldn't require overshifting to suddenly require it.

Lt Stonez

https://www.google.no/search?ei=U0W9...k1.r4QuX9ExGGc
This will be realeast any day now.

52telecaster

I was able to shift between 46-26 relatively easily with an old suntour FD. Currently I use a 40-26 crank and 12--36 10 speed cassette. Its all the gear I need. With 700x35 tires my gear range is about 20 to 90 inches.

Leebo

A mountain 3x9 works well for me. OP ,look at what what the lowest G.I. you will want, go from there. I use my 22-34 all the time on the New England hills and mountains. 22-34-46 with a 34-11 cassette works well. I too am on the larger side and ride a not light bike+gear. Spinning beats walking/mashing in my book. Seems like you are trying to kludge the gearing as opposed to dialing it in right. My 46 was great for flat to slight ups and downs. For me, a 40 or 42 would be spun out on flats or slight downs. IMHO. I would always opt for the lowest gear I could get, you don't always have to use, but its great when it is there. Nothing worse than redlining 2 hours into a 8 hr day. And pushing your bike up steep pitches.

robow

You're right in that it can get him down to 20 gear inches but those last few cogs will force some rather large and not fun steps.

mstateglfr 

Ill pile on.
You are blaming something on triples that doesnt inherently exist because a triple has 3 rings. The issue doesnt exist for all triples, only a small small segment.
Also, bar end shifters are not a problem here. In fact, bar end shifters allow are good for this small small issue of overshifting on wide range jumps from middle to inner rings. They are a solution as they are infinitely trimmable, unlike STI shifting.
Bar end shifting doesnt mean a drivetrain will now require overshifting. All my friction shifting(bar ends, bar cons, flat bar shifters, and Gevenalle) can drop a chain right onto the inner ring without issue. This is because the jump from middle to small ring isnt extreme.

There is plenty to complain about for bar end shifters and triples which is legitimate- stick to those complaints as you wont be wrong so often.

fietsbob

White VBC Crank lets you choose,, inners 24 ~ 38t, bolts to the outer 38 ~ 53t, the outer attaches to the crank..


Over shifring is juat what you did untill the engineers took that skill away from you, But they engineer a fixed cimbination.

the inner is 30t, middle 39, outer is 52~3.

going off the reservation to that 22 or 24t , the chain has a bigger climb up to , say, a 15t difference than 9t.

want faster shifting leave your STI drivetrain as it Is.





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nickw

+1 on the VBC, this is the route I went. 30 x 44 with a 11 x 32 out back....wide range of options though, especially with smaller chain rings and MTB rear derailleurs.

linus

You should try it. As long as you have 11sp, 11-40T is not bad. And I'm used to 11-23T cassette on my road bike.

chrisx

It still shifts, small loss in smoothness. Hold the new chain ring up to your deraileur and see if the clearance is there. Is the deraileur cage wide enough, van you move it down without it bumping the chain stay?

Why not solve the problem by switching to an 11 speed cassette? My 985 40 28 with an 11 42 work good on a 26 inch mt bike-touring bike. For my 29er I will buy an 11 46.

play around with the gear inch calculator. 28 42 on a 26er gives about the same gear inches as a 28 46 on a 29er.
BikeCalc.com - Bicycle Gear Inches Chart

If you are touring on a 9 or 10 speed cassette 28 is just to big.

shelbyfv

I think your fear of bar ends is unfounded. See if you can find someone to show you how they work. As others have said, overshifting is not inherent to use of either component.