On an older sport tourer, I have a triple front of 52-42-32 and a 7 speed rear HG50 thats 14-32.

It has more than served me well, even with a 1-1 ratio as the bailout and a gear inch of 27.3 at the smallest. I use the bike for what is either flat or gently rolling land and haven't come close to walking when loaded.

But, would a 13-34 cassette be significantly better?
It would give a gear inch of 25.7 at the smallest.


So 2 questions-
- is a 1.5 inch change at the low really felt?
- my current is 21-24-28-32 and the other would be 20-24-29-34. Does the 34t cassette with a couple of 5 tooth jumps shift worse because of the wide range between jumps?



I am feeling winter bad since I am actually pondering this so much and debating on making a change for what may be just because I want to change something.

I try to keep things like this simple.

In my lightest load condition do I find myself trying to upshift to a taller gear to go faster, if so gear larger in the front or smaller in the back to correct.

In my heaviest loaded condition do I run out of gears going up hills? Will I see higher/steeper hills this coming year? Smaller in the front or larger in the back.


Think about your next tour and your last tour. Where will your heart take you and what would you change about your last trip?


Best of luck.

Personaly , I'd drop the front to a 28t inner, the bang for the buck will be better and achieve a smoother effect.
Just my 2¢ for what it's worth

agree completely, first of all a 1.5 g.i diff is pretty darn piddly, and going up to 5t diff is not that much fun, not for me anyway and a 28 granny will keep you with what you are used to riding cassette jump wise but the lower gear inches will at times be nice.

mstateglfr, Because 1.5 GI is so small a difference and the possibility that the five tooth jumps between adjacent cogs maybe too much to trim for minor things like a headwind, I wouldn't make the change.

Brad

I am running a road triple with an aftermarket 24t granny. Photo shows my 52/42/24 triple with a 11/32 8 speed cassette.



The derailleur cage will not wrap up enough chain if I use the 24 front with 11 or 12 rear, but you do not have those rear cogs. Even if I could use them, I would not because it is severely cross chained.

The up shift from the 24 to 42 is not very smooth, but I can live with it. I use a chain catcher to prevent dropping the chain on the down shift to the 24.

You could try 24, 26 or 28 for a granny.

Switching to a 28t inner is definitely a possibility. My current inner ring is a 74bcd ovaltech and I haven't found any 28t ovaltech rings. Was hoping to keep all the rings the same, for no reason other than look. Trying to have my cake and eat it too!


After reading thru this, it looks like those 5tooth jumps would be noticeable compared to the current 4tooth jumps, so your suggestion is probably best.

I rode a bike with a 13-15-17-20-23-26-30 seven speed for years, so if you wanted to get some closer jumps (and if this cassette is still available) with a smaller granny you might get nicer closer jumps and still low enough of a low gear for you.

you would have to do a gearing chart to see what this would give with a given new granny, and maybe its not possible to find this cassette anymore, but perhaps its an alternative for you (lets say if you needed a new cassette anyway and were going to change the granny)

my old bike in question had a 24t granny and 40t midring, so a 16t jump which was ok but not great, but gave me the lower gears I wanted with the existing 13-30 cassette. For you a 26 granny would give you a 16t jump to your midring, I wouldnt go smaller than a 26 granny from my experience.

re your oval rings, too bad it wasnt 20 years ago as I could have not thrown out my biopace gears and given you the 28 that was on my bike.....(hated them so much I threw them out)

I like 10/16t spaced triples , so a 52-42-26 granny about 1/2 the tooth count of the big one.

Shimano's K cassette is a good 7 speed set.


My Touring rig uses A freewheel (Bullseye 'Tandem' Rear F/W Hub) 13~34t, 6 speeds

It's not the absolute gear inch change, it's the percentage. 1.5" means little for a 90" gear but it's 10% for a 15" gear. For this case, it's (27.3/25.7 - 1)=6.2%. That's not a lot but if you're on the verge of being able to keep climbing it's all you'll need.

Holy **** and I was worried about having a 24 to 39 shift, I thought a 16 teeth difference was the max possible.

I'm with most of the other posters that you'd be happier shrinking the granny ring a little. That's if you really need a lower gear.

Same here. I'm actually plotting tighter and tougher gearing for my main road bike (a 13-21 cassette and 42T small ring rather than the current 13-23 cassette and 39T small ring), but wondering if Future Scott would hate me for it later.

the 13t diff on my brifter bike works well (26t to 39t) and was worth it to have to go up two gears at the back when you go down to the 26 granny from the mid 39, and if I wanted to go up three it is just 3 quick stabs at the brifter.

the 16t diff on my old dt shifter bike often had me shifting up three gears at the back, but usually two worked well when loaded because the bike would slow down enough that two was just fine--I would say that for unloaded riding the 16 is a lot--but then again, thats what tons of road bikes have with their 50/34 so I guess you can take that with a grain of salt (but these bikes are much much lighter than even a naked tourer, so its much easier than on a heavier bike)

really what it comes down to is how putting on a smaller granny is a quick easy way to get your gearing down, and for me the compromise is ok because for a lot of the time Im in the mid chainring and for climbs will often have a bunch of gears in the granny so Im in that for a while anyway. An aside, this is one thing that is nice having a 9 speed vs a 7 is that there are a couple more useable gears in a given chainring. Having ridden 7 speed for a long time, then 8 , then 9, as long as drivetrains are reliable and last a decent amount of time (mine always do) I'll take more gears in back, nicer to have smaller percentage jumps between shifts, pure and simple.

to the original poster, go to sheldon browns gear calculator and do a few charts for your bike with diff grannies and diff cassettes. Its nice to see the percentage between each shift, as well of course seeing what gear inches you have now and what a given change will lower your low gear. Just put in "gear inches" and your wheel size and then plug in diff stuff, do screen shots of them and save them so you can compare.