Cycling UK Forum

Hi All

I have a Shimmanno105 Groupset on a roadbike.

50\34 Compact Chain ring
11 speed 11-30 Cassette

I live in a hilly area and have heard switching to an 11-32 cassette will be a good move to consider (the hills are a rather punishing and im pretty sure i end up cross chaining which is obv not a good thing)
.
However have also read the jumps between gears on an 11-32 are not optimal and an 11-34 would be better...?
Im really not sure what is meant by this..?

As the small cog teeth count remains the same i assume it wont affect spinning out of gears during the fun part of going down these hills ..?

Would peeps here suggest going with 11-32 or 11-34 and why ..?

P

The difference is Not a lot, I usually run with 32 (Southern Scotland hills) but I do have a 34 sitting there which I put on for a LEJOG. because I’d heard about Devon & Cornwall.

PaulK wrote: ↑20 Apr 2024, 11:05am Would peeps here suggest going with 11-32 or 11-34 and why ..?

Gears are an incredibly personal choice - what one person regards as the bare minimum, another would consider too easy.

Ultimately you're actually not changing much so realistically, probably either would be fine - it's not like you're after an entire new groupset. First thing is to work out where you're struggling - what sort of gradient, distance etc is the point where you're beginning to suffer? Some of it will depend on you - your age, weight, fitness, riding style, the bike you're on* and what (if any) load it has on it as well as where you're riding and your average speed.

I like https://www.gear-calculator.com/ as a handy visual guide, it allows you to put in your current gearing set-up and then compare to other so you'll be able to "see" where the gaps are which can really help in understanding the changes before you start buying cassettes and changing things around.

*as a rough general rule, road bikes with their more "aggressive" posture behave better with higher gearing while gravel / touring bikes are optimised for lower gearing but it'll vary a lot depending on set-up and riding style and there are certainly plenty of people who potter along country lanes at 12mph on very "racey" road bikes!

PaulK wrote: ↑20 Apr 2024, 11:05am However have also read the jumps between gears on an 11-32 are not optimal and an 11-34 would be better...?
Im really not sure what is meant by this..?

Optimal for what or who?! Honestly, that sounds like either marketing talk or a reviewer trying to sound technical. IME, most people barely know how many gears they have never mind what ratios they are and would probably not notice if you removed an entire cog - the idea that people are riding along going "oh gosh, I don't like the 3-tooth gap between the 18 and 21 cogs, it really affects my carefully optimised cadence..." is just nonsense!

PaulK wrote: ↑20 Apr 2024, 11:05amswitching to an 11-32 cassette will be a good move

It's a small move.

If the current steepest hill you could manage were 15%, the change would increase that to 16%. That wouldn't be a lot of help if you aspired to climbing 25% or 33% gradients. If you want lower gears, there's a lot of scope for reducing your chainring size.

My gears (which I use for fully laden touring in places like the Lake District) are 22-32-44 & 11-34, which gives me a bottom gear of 17.5", but on similar gradients without the luggage, I would need about 22" to be equivalent. By comparison, your proposed change, even to 34t, will give you a 27" bottom gear.

I would suggest that the change from 32 to 34 is so small as to be “lost in the noise” of other factors such as the weather, the mood you’re in, whether your water bottle is full or empty, etc, and one that you’d quickly forget you ever made.

I made a 10% change to bottom gear on a previous bike, so somewhat greater than you are proposing, and that was just about worthwhile, but only just.

Whether it’s worth making a change at all depends, I suppose, on how much the present bottom gear is compromising your enjoyment, but if it is worth changing, I’d suggest a greater change.

the 11-34t cassette is arranged much more like a touring cassette, so there is no 14t or 16t sprocket but there are still close intervals elsewhere, such as 19-21-23-25-27, which is quite different to the 11-32t cassette. Personally, I prefer touring ratios that start 13-15-17-19-21t because I regard the 11t sprocket as a waste of space, and 13t is quite small enough. However, for any kind of racing these ratios would not be high or close enough.

Horses for courses, innit.

I have just changed from my prefered 9-s (put-together) ratio of:

13-14-15-17-19-21-24-27-30 to :

13-15-17-19-21-24-27-30-34.

The majority of the sprockets come from an Ultegra 12-27 cassette. The additional 13t
end sprocket and the 30 & 34 (from an 11-34) cassette aren't used that often, so when
the time comes to change the cassette, those sprockets can be used again. YMMV.

Nearholmer wrote: ↑20 Apr 2024, 2:34pm I would suggest that the change from 32 to 34 is so small as to be “lost in the noise” of other factors such as the weather, the mood you’re in, whether your water bottle is full or empty, etc, and one that you’d quickly forget you ever made.

I made a 10% change to bottom gear on a previous bike, so somewhat greater than you are proposing, and that was just about worthwhile, but only just.

Whether it’s worth making a change at all depends, I suppose, on how much the present bottom gear is compromising your enjoyment, but if it is worth changing, I’d suggest a greater change.

Strangely - I'm agreeing with Nearholmer... changing from a 30 to a 34 tooth, reduces your gearing by approx 3 inches per pedal revolution - down from 31 to 28 inches....

If it was down from 39 inches to 36 inches, I'd say do it because you may feel a difference however as 31 inches is already small... I'd say you probably wouldn't...

At this point I'm hoping for a responsible adult to come forward (CJ....?) to tell you all about the joys of throwing your 'orrible compact chainset into the corner of the shed and fitting an nice alpine one, to drop the inner ring size to 24 inches... at which point, with enough traction you should be able to climb up the size of a house...

Personally I get off and walk now, to help my bone density

Gears are normally 13 or 14% apart. going from a 30 to 34 is 13.3% so it is a full extra gear for climbing

going from a 30 to 32 is only 7% so its like half a gear, you probably won't know you have changed anything.

There is also an 11-36 available but whether that would be beneficial I wouldn't know.
You could also go to a 40T cassette but that entail a derailleur extender or a different RD.

I have an 11-32 10 speed105 on my fast road bike and an 11-34 10s Tiagra on my heavier CX. To be honest I don't notice much difference between the 2.
If your derailleur can take it I'd go for the 11-34 on the basis I have never wanted for a higher bottom gear. As others have said the difference in this case is almost negligible.

cycleruk wrote: ↑20 Apr 2024, 5:21pm There is also an 11-36 available but whether that would be beneficial I wouldn't know.
You could also go to a 40T cassette but that entail a derailleur extender or a different RD.

Or even 11-42 which I have using the Spa cycles extender link and which gives 40% lower gearing than a 30T sprocket. The OP is the best judge of whether adding one step lower gear is enough or more is required. I know that my legs aren't getting any younger so it's nice to have a spare gear at the bottom of the range ready for an unusually challenging hill. I chose the Shimano Deore CS-M5100 cassette which has fairly even increments (28-32-37-42) at the low end. Some cassettes have a big difference between bottom and the next gear.

The OP also mentioned cross chaining. I think the risk of doing this is less on a wide range cassette as the biggest cogs are needed less frequently.

Hi all

so many thanx for all the replies.
Ive been out all day so not even chance for a ride on one of the first few nice dys in the year !!

Lot to go over there, I think i may go with the Ultegra 11 speed 11-34 (assuming it fits think i will need a new chain tho)
https://bike.shimano.com/en-EU/product/ ... 00-11.html
11-13-15-17-19-21-23-25-27-30-34T

Where the Ultegra 32 is
11-12-13-14-16-18-20-22-25-28-32T

And my current 105 looks to be
11-12-13-14-15-17-19-21-24-27-30T

Either way (11-34 \ 11-32) im gonna have to suck up the possibility of cross-chaining it seems.

ATB
Paul

PaulK wrote: ↑20 Apr 2024, 8:30pm Lot to go over there, I think i may go with the Ultegra 11 speed 11-34 (assuming it fits think i will need a new chain tho)

It's good practice to get a new chain with a new cassette anyway. You might find it needs to be a link or two longer, also the b-tension screw on the rear mech may need a small adjustment.
By the way, the 11sp 11-34 cassette comes with a 1.85mm spacer which needs to go onto the freehub. Your current 11-30 won't have that but the 11-34 will need it.

PaulK wrote: ↑20 Apr 2024, 8:30pm Either way (11-34 \ 11-32) im gonna have to suck up the possibility of cross-chaining it seems.

Cross chaining on a 2x11 is irrelevant, the system is designed to run all 11 cogs in the big ring. Assuming the chain is long enough and the gears correctly set up, you'll get all cogs with no issues.
The only one to avoid is small-small. Some electronic gear systems specifically prevent you selecting that gear when in normal riding mode, it'll only permit it in adjustment mode.

But big-big is fine.

Grrrr just been reading the specs

I apparently have a 105 short cage rear derailleur who can support an 11-30 cassette as maximum.
Need to change the rear derailleur too it seems..

Is Ultegra shifting better over 105 etc..
I dont mind paying the extra money (about £40) if there is some solid benifit otherwise will prob stick with a medium cage 105 rear derailleur.

ATB
P