Rushie

Hi all, Looking for a bit of advice on rear cassette change. I'm a relative newbie to road biking (done lots of MTB) and am struggling a little with the ratios on my (first) new road bike ... basically struggling up the hills as am much more used to having a bigger cog on the back and having a high cadence.

It's an 11 speed 105 groupset and the rear cassette is 11-30 and am considering changing it for 11-32 to give me a little more help on the hills.

The question is would I notice this relatively small change or would it be a waste of money? Anyone done it ? Should I just persevere and hope my fitness and power improves over time ?

I'm not doing Tour De France type hills, just the odd steep one or two round where I live in Hampshire UK .

Any thoughts or advice would be much appreciated.

yaw

What is your current climbing cadence and small chain ring size?

You can calculate what difference a 32 or even 34 would make over your 30 and pick accordingly.

If you are close enough to the 70s and up for most of it then I would just stick it out and climb more.

delbiker1 

Very little difference between 30 and 32. If I was going to do this, it would definitely be at least 34t big cog. You do not state what RD or crank set you are using. lf you have a short cage, the 32 might work and 34 most likely will not. Medium cage and that should be fine. You might need a longer chain. Here is a gear inch chart I like: kstoerz.com | visual drivetrain comparison tool. Struggling a bit when climbing, when you first start road riding is pretty normal, even if you have been an avid off road cyclist, it's different. Muscles are being used in a new way, and, I think a good bit of it is mentally getting accustomed to it. What kind of climbing are you talking about? Maybe give it a bit of time before going ahead.

Rushie

Thanks chaps, really appreciate the advice and you taking the time to respond... from your replies I think I'll stick it out for the time-being then and see if I can retrain my muscles to road biking by doing a few more miles on the hills :-) .... I like the drivetrain tool though, very useful !

For context I basically bought an entry level Carbon bike (Boardman 8.9 Carbon) which has these specs :

• Cranks:FSA Gossamer Compact 50-34
• Front Derailleur:Shimano 105 braze- on
• Rear Derailleur:Shimano 105 11 speed
• Shifter:Shimano 105 2x11
• Cassette:Shimano CS-R7000 11 speed, 11-30
• Chain:KMC X11

Troul 

are you struggling solely to the 30, or are you struggling with more than the one cog when riding? If it's the later, you might benefit more from a crank gear change (1x 2x ? ) If it's 2x, that would make me want to change the inner crank gear to achieve better climbing.

If you are only needing that one cog to spin a little faster when going up a hill, then a 32 could make more sense, but if you have to change other parts to support the cog change, minds well go with a 34 instead.

PeteHski

I think the 11-34 cassette would be the minimum worthwhile change. You would definitely notice the difference. For reference, second gear on the 11-34 cassette is 30T, so it basically gives you 1 full step lower gear.

One of my bikes has Shimano 105 with a compact 50/34 front and 11-34 cassette and I use the 34T on climbs steeper than 10% or longer alpine climbs above 6-7%. It's not a massive difference, but signficant. But if you want to be truly spinning up steep climbs like you might on your mtb, then you need to look at gravel bike gearing with a 40T+ cassette and smaller chainrings e.g. Shimano GRX. But that's a whole new drivetrain. I think the biggest cassette you can fit on current 105 without modification is 36T (SRAM 11-36T is compatible).

Rushie

Thanks for the advice ... Just the 30 is really the problem when I'm going up hills ... typically when I'm > 20 miles into a ride, before that I can turn it relatively ok on the hills where I live ... Guess with my current fitness and power levels I just struggle to climb in that gear when I hit 20 miles or more on a ride, I seem to keep searching for another gear ! ... a 25 mile (hilly) ride is a decent ride for me at the moment .... probably the solution is to train more and get used to it for now and if I'm still struggling in a couple of months I might try a change to the 32 ...

PeteHski

If you have the medium cage 105 R7000 rear mech (which it probably is if it was a new bike) then I would just get the Shimano 11-34T cassette.

delbiker1 

The 105 set up you have is a very road gearing spread. The 105 rear derailleur very well could be a medium cage. When I purchased my 7000 groupset, the medium came with it when selecting the 30T small cog, which I did. 34-30 is pretty low unless you are doing some serious climbing. When using the gear inch charts, it is good to get some on the road experience knowing what gear you are in, so you can actually relate to the differences in your brain. What looks or sounds like a large or small gap on a chart, may not seem so big in the real world. Ideally, when selecting a gear spread, one should take into consideration where and how the riding will be done, then opt for gears that will give a bit more high and low end than you are likely to use on a little less than average day. at least, close to it.

SoSmellyAir

If you have made it so far on the 30T, you should be able to build up your fitness in a few months that you would not need a lower range for the same hills. Vary your routes so you get used to climbing both earlier and later on in your rides.

Iride01 

What is the slope of the hill that gives you trouble and for what distance are you having to climb it? Does it give you trouble when you are fresh, or is this after 2 hours of riding?

Though you have done mountain biking, you still might have to just ride some more and build up the muscle that will let you ride that hill more easily. And If you aren't having to get off and walk, then I think it very likely your legs will get stronger.

If your rear DR will handle it, a 32 tooth might give you that little extra to keep you from wearing yourself out. Hang on to the 11-30. Once your legs get stronger, you can put it back on.

Koyote

Since you're a newbie and likely not doing your own wrenching, just go to a shop and ask if they can install an 11-34 -- as others have noted, the 34 will be a noticeably lower gear. Your rear derailleur should be able to handle that. But be forewarned that you'll likely also need a new chain, so this will run you well over $100 with the labor.

blkwrxwag

I have a 105 R7000 bike with a 50-34 and 11-34 cassette. I live in the hills and use the 34-34 a lot. Go 11-34 if you are going to change.

xroadcharlie

If you can make it up with the 30T cog and 34T chainring but it takes a lot of effort, Then a 34T sprocket on the cassette would most likely work well for you. It's not worth the effort to go to 32T. As pointed out in a previous post, a 34T sprocket is 1 full cog lower the a 30T.

Even then we're still talking about 27 gear inches. That's a far cry from mountain bike gears, but a road bike probably climbs easier on a paved road then the heavier mountain bike with wide knobby tires on gravel. It is probably sufficient for most cyclist.

Myself, I'd opt for a 46/30 chainring instead of changing the cassette, Same low gear as a 34T cassette, but you retain the closer spacing of the 30T cassette and a high enough top speed, 45+ kph with 46/11 cogs.

biker128pedal

Is this the bike? If so you could go a 34 and maybe a 36.

https://www.boardmanbikes.com/us_en/...-8.9-2021.html

Carbonfiberboy 

This is really pretty simple to calculate. Go climb a hill which causes you to bog down. Note your speed and cadence. Enter a speed and cadence calculator like this one: https://www.machars.net/bikecalc.htm
Decide what you'd like your cadence to be at that speed, say 80, and mess with gear combinations using your current chainring. You'll find how big your largest cog should be.

Canker

MIght even want to go 11-36 or even 40. Just get a wolftooth roadlink to get around the limits of your RD. I've never been riding up a hill and thought "gee it really sucks having this easier gearing".

SoSmellyAir

True, but plenty of people have thought that the (gear ratio) gaps between the physically smaller cogs in a 11-32 cassette are too large and disruptive to their cadence.

11-30: 11, 12, 13, 14, 15, 17, 19, 21, 24, 27, 30
11-32: 11, 12, 13, 14, 16, 18, 20, 22, 25, 28, 32

That was why I had urged the OP to stick to the 11-30 cassette.

tempocyclist

Unless you're getting off and walking, stick with the 11-30 and suck it up. You'll very quickly get stronger and wonder what you were worried about.

But if you do have to switch cassettes, go with the larger 11-34T one. You may as well. You'll certainly notice the difference in being able to spin up the hills.

Rushie

Thanks to all for the comprehensive advice, really appreciate it - mand has helped a lot. Think I've decided to stick with what I've got for a couple of months and see how I go, and if I'm still struggling then switch to an 11-34 - but keep my 11-30 to switch back in when my legs are a bit more accustomed to road cycling next year maybe !

PeteHski

What I often observe on events involving significant climbs are loads of people grinding away at ridiculously low cadence, who would be far better served with much lower gearing. It's not just a case of getting up the climb, it's also a case of maintaining a reasonable cadence to make it more efficient. Road bike gearing has only just woken up to this simple fact in the last few years and I still think it's a bit behind the curve set by the mtb crowd. I find even a compact 50/34 and 11-34 cassette can be a bit marginal at times and I'm a reasonably strong climber. But our local UK climbs are very steep (often north of 20% gradient in places).

For sure the OP will get stronger with practice, but will still almost certainly gain efficiency from a lower gear. The difference in cadence for a given speed between a 30T and 34T is approx 10 rpm. So if you are bogged down to 60 rpm with a 30T, you would be at 70 rpm on a 34T and likely feeling much more comfortable.

rm -rf

It's the ratio between the two gears. 32/30=1.07, or 7% easier.
Depending on the tooth counts, shifts to the next gear can range from around 5% to 15%+ percent change. It's often around 10% or so.
Your 27 and 30 largest cogs are 11% difference.

So it will help, but not a huge amount. I don't think it's worth the change to a new cassette.

11-34: some riders really like this, but others notice the larger gaps between shifts on more level terrain, so they never quite get the right cadence. "a bit too hard to pedal--shift one easier" -- "now it's too easy, shift back to the original gear"

Joearch

I do some climbs in the hills in Los Angeles area. I have the 50/34 and 11-34 cassette on both of my road bikes. Climbs are in the 4%-8/9% some lasting 10-15 minutes. I will say that at 65 yo I do appreciate the couple of gears that get me over the top. I don’t find the gaps in gears to be an issue for me at all. Both Shimano, one is a 105 the other is Ultegra.

SoSmellyAir

This gearing calculator would help visual the difference between the two cassettes for a given cadence (e.g., 90 rpm):

Bicycle Gear Calculator (gear-calculator.com)

You can play with the cadence slider to what difference a different cassette would make at a given speed.

cyclezen

This is a great tool and helps visualize the gear jumps on any crank/cassette (freewheel) combo. Whether you go old school 'gear inches' or 'gear development', you 'll get a feel for what gears work for you and when...
As noted a 2 tooth change in those low end ranges, is hardly noticeable...
if you're gonna get a different cassette, going to 34 or larger cog is about where you might notice the change.
I wouldn;t try to tough it out.- I'd work with 2 cassettes.
Get a chain whip and cassette lock ring tool, and learn one of the easiest 'mechanic' jobs for the riding. (you want a large adjustable wrench also...)
Piece of cake swapping cassettes, quick to do, and gives you skills you'll eventually want to learn - applicable for all derailleur shifting systems...
Most often swapping cassettes requires no 'adjustment' in the shifting system..
If you get the 11-34, you'll also have a 28, which you can use when you want to 'tough it' for a bit, but then have a more comfy gear, when 'tough' isn;t what you want...
... you'll also get stronger riding the 34...
Like Lemond noted "It never gets easier, you just go faster..."
Ride On
Yuri