fthomas

I recently purchased a Jamis Aurora Elite. Like the bike and still need to work on some fit issues (the saddle is going to have to be changed) and am thinking of switching out the cassette to a 11-34 ten speed.

Will I see that much of a difference on hills?

DrIsotope

I swapped out an 11-28 Ultegra in favor of an 11-32 XT, and yeah, there's a significant difference. I would have gone with an 11-34, but I didn't like the ratios in between compared to the 11-32 (the gear right below the 32 is a 28, so I know the feel.)

bwgride

Yes, especially up hill with a load. You can calculate distance traveled here

Bicycle gear inch calculator

chasm54

Yes, that's a difference of over 13%, it would be very noticeable. Personally I'm not a big fan of the gaps between the ratios on that cassette, but if you want more help at the bottom end that'll give you it.

Tourist in MSN

Will your rear derailleur take it?

If you do that, you might want to have a slightly longer chain. While your existing chain should work fine, if you ever accidentally shifted into your largest chainring and largest rear cog, that is when you might regret not having added a few links or replacing the chain.

timdow

Your derailleur is "medium cage" and is advertised to only shift up to a 32T cog, but I read that it will shift a 34T.

I don't understand why a bike of this type is fitted with a 30/39/50 crankset. After sorting out the cassette if you still find your gearing is too high for the load you want to carry, you may want to look into changing the small ring. Take a look at: 74 mm BCD Road and Mountain Bicycle Chainrings (Chainwheels) from Harris Cyclery .

Darth Lefty 

Shift ratios for two step gearing. I agree a lower granny would be nice.

Walter S

Yes

timdow

So your saying that a 30/39/50 gives true half-step (two step) gearing? I didn't run it through a gear calculator....

Do we really care about 1/2 step with 30 gears anyway?

fthomas

The bike has a Shimano 105 RD-5700-GS Long Derailleur. The alternative is to go with a smaller front chainring - 30 down to 24 or 26. That would be the least expensive way I think and would give the same results. Is there a negative to this I might be missing?

robow

You may or may not since you really only have 14 different gear ratios without the overlap between chainrings with that 3x10 configuration and an 11-34 cassette.

chasm54

39 to 24 is a very big drop. You might be better off just putting on a 48/36/24 chainset and be done with it.

Carbonfiberboy 

I ride 2 bikes with 52-39-26 triples. One is our tandem which we use for both sport and touring. It has a 12-34 cassette. The other is my light climbing bike, which has an 11-25 cassette. The 26 is there for different purposes on the two bikes, but they both shift well. I use an N-gear chain catcher on both bikes.

fietsbob

have 3 50-40-24 triples a 52-42-26, and a 48-36-22. friction shifting all of them .

Darth Lefty 

No, 2-step. One shift on the front is equal to two on the rear. Many gears overlap, but the shifts are nicely spaced. Works very well with indexing - pull one trigger for one step up, pull both triggers for two down + one up = one down.

Some MTB setups take this even further where the 1-2 front shift is matched to big jumps at the bottom of the cassette and the 2-3 front shift is matched to smaller jumps at the top of the cassette. I have my MTB-tug set up this way and I like it a lot.

Half-step is where one shift on the front is equal to half on the rear. This is great with 5-speed touring freewheels that have huge shifts but I don't see the point with cassettes or indexing.

chasm54

Yes. I have this set-up on a road bike and like it a lot, both for this reason and because the 30 inner ring allows a decent climbng gear while keeping nice tight ratios at the back. But I'd want something lower for loaded touring.

fthomas

Sorry I don't get this one. The bike has a small chain ring of 30, so dropping to 24 is a bit more than going to a 11-34 from a 11-30. Both would be my preference if my RD and finances would handle it.

I have only been able to find the Shimano instructions for the 105 RD-5700-A, which even with a long cage only handles 11-30. Wish I had put a little more thought into it when I bought the bike and had the changes made at that time.

Hope this is a reminder for others that know the intended use of their bike, area(s) to be ridden and the stock gearing on the bike. I blew it on this one.

gregjones

I had a 30t and went to a 34. Love it.....not for the granny low, but it keeps me on the middle ring for just the bit more that I needed. Small ring isn't used much without the trailer.

Medic Zero

.

I definitely notice the difference between 11-32 and 11-34 on 8 and 9 speed set ups, particularly loaded (I haven't run a modern 10 speed). But my home turf is pretty hilly. My small rings on my triples are 22T, and 24T on a legacy crank and I still often wish for those extra 2 teeth, front or rear.

chasm54

I was referring to the big step down from a 39 middle ring to a 24 inner ring. My personal prefences would be to keep the rings slightly closer in size. YMMV, it's a matter of taste.

fietsbob

once on the 24t I leave it there until i get to the pass and then up shift as I head down the other-side.

18 speed.. 3 by 6.

timdow

My thinking is that you can't just change the rear "D" due to the incompatibility between road and mountain with 10 cog. The indexing on the bar end shifters would be incorrect... unless you can deal with friction only.

With 130/74mm I believe 38T is the smallest you can go for the middle ring, so probably not worth changing from 39T to 38T.

You can do the cog swap to 26T and see if you are satisfied, but you might might consider just shopping for a 110/74mm crankset. If you do the cog swap, an anti-chain suck device is highly recommended.


Here is some good reading regarding possibly getting the derailleur to shift a 32T : Downgearing Your Bike

nfmisso

And another series of suggestions:

* M592 RD (9 speed mountain, works with 10 speed road shifters)
* 11-36 10 speed cassette (Shimano or SRAM - check which has more suitable spacing for you)
* 48-36-24 front rings. (or compromise, just 24 granny ring).
* new KMC chain.

timdow

Do you think that will work? Will the 9-speed mountain RD shift the 10 cogs with tighter spacing?

nfmisso

It will, used by many people. Note: 9 speed MTB RD, with 10 speed road shifters. It will not work the other way around.

Read the reviews: https://www.amazon.com/Shimano-Deore-...&keywords=m592