Bicycle Mechanics - Help Rear Cassette 11-32 or 11-34

Running 26, 36, 48 on Front. Bicycle is a 2001 Sirrus. Looking at changing rear cassette, do I choose 11:32 or 11:34 at the back. Does anyone have any experience of the different steps between these gears.

11,12,14,16,18,21,24,28,32
v
11,13,15,17,20,23,26,30,34

I use the bike for commuting pretty flat, but hit the hills at the weekend.
Lastly if I fit the 11-34, will I need to adjust the chain any ?

Thanks

I'm not a mechanic, but: what are you running now? If you add more teeth with an 11-34, you would need to add links- but, any time you go to a new cassette you want to use a new chain anyhow. And, some (most?) rear der. for triple drivetrains work to 44 teeth maximum, you might have a problem with the 22 diff front, 23 diff rear. IF this 44 teeth max is strict.

I'm not a mechanic, but: what are you running now? If you add more teeth with an 11-34, you would need to add links. And, some (most?) rear der. for triple drivetrains work to 44 teeth maximum, you might have a problem with the 22 diff front, 23 diff rear. IF this 44 teeth max is strict.
At the moment running 26,36,48 on Front with no issues, bike came like that. Looking at either

Current 11-32 on rear or 11-34. Has anyone used the 11:34 and found any issues ?

At the moment running 26,36,48 on Front with no issues, bike came like that. Looking at either

Current 11-32 on rear or 11-34. Has anyone used the 11:34 and found any issues ? If it's got a a 32,and a mtb RD,a 34 should work,but make sure the chain is long enough for the big/big/

11-32, Deore rear derailler

Do you try big/big threading through derailleur or outside ?

To me, the big question has to do with what gear you need to hit the "sweet spot" on the flat. One of those cassettes has a 16t cog, the other has a 17. If you're like most people, you will find one or the other of those cogs indespensable.

Do you try big/big threading through derailleur or outside ?

Run the chain around the big/big combination bypassing the rear derailleur entirely, then add one inch of chain.

To me, the big question has to do with what gear you need to hit the "sweet spot" on the flat. One of those cassettes has a 16t cog, the other has a 17. If you're like most people, you will find one or the other of those cogs indespensable.

I suppose it is a matter of trial and error.

I use 23/36/46 rings with 12/27 cassette normally, but I use a 12/34 rear for the mountains (no level ground). I add a few links of chain and another SRAM gold master link. I far exceed the capacity of the XT rear derailleure, but it doesn't matter as I don't use the big ring and the two smaller cogs anyhow. Works fine and if I do mistakenly use that ring/cog combination, the chain just rubs against itself and the noise alerts me.

Al

To me, the big question has to do with what gear you need to hit the "sweet spot" on the flat. One of those cassettes has a 16t cog, the other has a 17. If you're like most people, you will find one or the other of those cogs indespensable.True.

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Motorhommmer, you could even buy both cassettes and hack them together into one super cassette and pick a range that suits your needs best rather than relying on Shimano's gearing choices.

11,12,14,16,18,21,24,28,32
v
11,13,15,17,20,23,26,30,34 <- Are you sure about the 20? Wouldn't that one be a 19 instead?
v
11,12,13,14,15,16,17,18,19,21,23,24,26,28,30,32,34 <- Quite a range to select from here.

Since you're running a tripple with a 26t up front how likely are you to need to go all the way up to 34 on the back? Are they pretty large hills?

Unless you have some absolutely huge hills, the switch to a 34t cog will gain you very, very little over the 32t set that you are using now. My wife, not a powerful girl, runs an Ultegra triple (53/42/30) with an 11/32 cogset on the rear and manages quite well in our very hilly/mountainous terrain here in eastern Washington State. I don't think the 11/34 will be worth your time, effort or money.

True.

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Motorhommmer, you could even buy both cassettes and hack them together into one super cassette and pick a range that suits your needs best rather than relying on Shimano's gearing choices.

11,12,14,16,18,21,24,28,32
v
11,13,15,17,20,23,26,30,34 <- Are you sure about the 20? Wouldn't that one be a 19 instead?
v
11,12,13,14,15,16,17,18,19,21,23,24,26,28,30,32,34 <- Quite a range to select from here.

Since you're running a tripple with a 26t up front how likely are you to need to go all the way up to 34 on the back? Are they pretty large hills?

Definitely a 20. Hillls are pretty good climbs. Wickow Mountains. Remember I have a 26 granny ring not a 22. Out of interest, I have here the Shimano Cassette - how to you open it to change rings. Is it a rivet or a very small allen key

What cassette do you currently have?

Here's the numbers on the others:
11-32
total range 22gi to 118gi
Avg % change between gears: 13.4%
Highest % change between gears: 16.7%. from #6 to #5

11-34
range: 21gi to 118gi
Avg % change between gears: 15.2%
Highest % change: 18.2%. from #2 to #1

Definitely a 20. Hillls are pretty good climbs. Wickow Mountains. Remember I have a 26 granny ring not a 22. Out of interest, I have here the Shimano Cassette - how to you open it to change rings. Is it a rivet or a very small allen keyIt will actually depend on the grade of the cassette. On two HG-50 (Deore or Tiagra) I knocked the rivets out. The shape of the freewheel body will keep them in place, althought it's more of a pain to put them on one at a time. The key will keep them from going on improperly though.

It will actually depend on the grade of the cassette. On two HG-50 (Deore or Tiagra) I knocked the rivets out. The shape of the freewheel body will keep them in place, althought it's more of a pain to put them on one at a time. The key will keep them from going on improperly though.

I think it is lx looks like a small rivet

At the moment running 26,36,48 on Front with no issues, bike came like that. Looking at either

Current 11-32 on rear or 11-34. Has anyone used the 11:34 and found any issues ?

With 11-34, there could be a problem with the derailleur too close to the cog, even when you unscrew a lot the "B-screw".
Also, look at how the chain behaves when you are on big-big (48 front and 32 rear). Is there a little bit of slack in the chain? If there is none, then you will need to add one link, otherwise you should be OK. Remember that

However, as I look at your current setup and price for upgrades, I would suggest that you change the front granny ring to a 24, keep the other two rings and and keep the current cassette as is (11-32, if I understand correctly). Using 24/32 gives you 20.25 gear-inches whereas using 26/34 gives you 20.64 gear-inches.

Another suggestion for your setup would be to disassemble your 11-32 cassette, buy a 11-34 or a 12-25 cassette, disassemble it also, and cobble up your own with closer ratios at the top and wider near the bottom. Hints on how to do that http://sheldonbrown.com/k7.html

BTW, my tandem has 48-38-24 front and 13-15-16-17-18-20-23-26-34. Not to tell you that you should go that way, but rather that it could be done.

Michel, thank you very much for your comments. Very helpful - as you can probably gather although I am at this for about 9 years now, it is only recently that I have been looking more at the gearing side of things. Cannot warm to an out and out road bike and using a Hybrid means you look more at cogs and gears etc.

With 11-34, there could be a problem with the derailleur too close to the cog, even when you unscrew a lot the "B-screw".
Also, look at how the chain behaves when you are on big-big (48 front and 32 rear). Is there a little bit of slack in the chain? If there is none, then you will need to add one link, otherwise you should be OK. Remember that If he has a Deore rear derailleur, why would the 34t cog have clearance problems? The Deore is an MTB der and shoudln't have any trouble clearing a 34.


However, as I look at your current setup and price for upgrades, I would suggest that you change the front granny ring to a 24, keep the other two rings and and keep the current cassette as is (11-32, if I understand correctly). Using 24/32 gives you 20.25 gear-inches whereas using 26/34 gives you 20.64 gear-inches.

Another suggestion for your setup would be to disassemble your 11-32 cassette, buy a 11-34 or a 12-25 cassette, disassemble it also, and cobble up your own with closer ratios at the top and wider near the bottom. Hints on how to do that http://sheldonbrown.com/k7.html

BTW, my tandem has 48-38-24 front and 13-15-16-17-18-20-23-26-34. Not to tell you that you should go that way, but rather that it could be done. Agreed. If he gets a smaller granny up front he may not even need much if any finagling on his rear cassette. It certainly would be the easiest thing to do. (I'm assuming he has crank tools, a chain whip and a cassette remover here)

If he has a Deore rear derailleur, why would the 34t cog have clearance problems? The Deore is an MTB der and shoudln't have any trouble clearing a 34.


I know. But I'm also aware that on my tandem, I use 12-34 and had to unscrew (or screw?) the B-screw all the way to make the derailleur hang very far behind the cassette, because otherwise the derailleur pulleys were hitting the largest cog. No problem like that on my Trek 520.

I once took a few measurements and noticed that the derailleur hanger of the 520 is located 3-4 mm downwards compared to the one on the Co-Motion. I can't tell you whether it's a deliberate design change of if it is simply related to the different sizes of the rear triangles. The Trek 520 is a 25" frame, while the rear end of the Co-Motion Primera is a 18" frame.

Heading south out of my home I almost immediately hit a 3.1%, one mile grade. After I changed from an 11-32 to an 11-34 cassette (with 30/42/52) I noticed a significant improvement in my comfort level. Generally, I climb with the 26, but on 'tired' days I drop to the 30 for some sections of the climb. On the level portions of my ride I don't notice any difference between running the 11-34 as compared to the 11-32. This setup gives me a 23-125" gear output. Quite sufficient for my doodling about.

You can get a free gear calculator at http://www.techmarc.co.uk/gearcalc.htm, and input your equipment, graph the output, and see if you like the setup before you make the change.

Measured things on the gear ratio. I think that the intervals on the 11-34 may suit me better, When in 48 and gear 7,8,9 there is an easier ratio. I may be able to avoid some double shifting using this mix.
SOO I have put on the cassette tonight and will try it out first thing tomorrow.I will post my results here so as to close out the thread from my end. May help someone else.

The comment about finding the sweet gear is very interesting and why I will try out this cassette.

Brian

It sounds like an awful lot of gears, how steep are the climbs? With a triple in the front I run a 48/32/22 with an 11-21 cassette. The granny gear is insanely small even with a 21. I can't imagine pedalling a 26f-34r up a hill.

CHEERS.

Mark

I'll soon have a 22-34 on my bike, for 16 gear inches.
And I know I'll wish for an even lower gear in some situations.
In my opinion, there's no such thing as a too low gear.

And the result is ........................

Well tried it out today. Great. A little known fact for me, but I like the 11-34 not for the large cogs gearing but for the small. It has 11,13,15 instead of the 11-32 which has 11,12,14. The 13 and 15 make the difference for me. I avoid a lot of double shifting and the gearing is that tiny bit easier soit works. The following are the gear inches comparison. Its the 84.8 v 90.86 and the 97.85 v 106.00 and the 74.82v 79.50 which do it for me, in additionI can just drop from 48f to 36 f whilst in 17F and it removes a double shift I previously was doing.
I now end up with a nice 74.82,84.80,97.85 and 115.64 whilst in the 48 outside COG.
Incidentally I did a lot of looking at a road cassette (12-21) for the commute but ended up with 84.8,90.96,97.86,106 in the large COG. I am indebted to the post with gear table as although these seem anal to go through, they do translate to reality when you hit the road. As for climbing, at the weekends I hit some pretty big hills (well as big as hills can be in Ireland) I imagine I will use 26/30, previously I would have used 26/32.

11-32 11-34
48F 11f 115.64 11F 115.64
48F 12f 106.00 13F 97.85
48F 14F 90.86 15F 84.80
48F 16F 79.50 17F 74.82
36F 16F 59.63 17F 56.12

Which is all a rather long way for saying my ideal cassette would be 11/32 but with 13 & 15 Cogs instead of the 12,14 COGS. By the time I would buy the 2 small cogs I would be well on the way to buying a full 11-34 by mail order.

I now realise I should have posted this on the commuter forum. Many thanks for those helped me out with the suggestions re: inner COG, gear calculator and sweet spot re:gearing.