Cassette Ratio - Hill Climbing

spturton

Hi,

I appreciate this has been covered numerous times before and there are 100s of articles all over the internet on it, but I still don't have the first clue about ratios.

I got into road cycling about 5 years ago and bought a Boardman Pro Carbon 105, which I believe has a 11-22 cassette. I'm looking at upgrading and, given it's recently moved to the Peak District, it's just hill after hill after steep hill.

What cassette should I be looking to get to make climbing a bit more manageable?

I was looking at getting a supersix evo ultegra which has an 11-32.

Thanks

webboo

If your rear is a five year old short cage one, it might not be able to handle a 32 tooth sprocket.

N0bodyOfTheGoat

https://www.sheldonbrown.com/gear-calc.html

11-32 (11-12-13-14-16-18-20-22-25-28-32) with 34/50 chainrings and a "700x28" GP4000S II that really measures ~32mm on my Cube gives me a gear inches range of 28.7 to 122.7 , I rarely use the 11T to 14T sprockets compared to using 18T to 32T on climbs.

11-34 (11-13-15-17-19-21-23-25-27-30-34) with 34/50 chainrings gives me 27.0 to 122.7 gear inches range. The increased range is quite tiny, but it effectively gives me eight gears for climbing compared to six, including an extra "bailout" one beyond the 28T

£36 at Wiggle for 105 tier https://www.wiggle.co.uk/shimano-105-r7000-11-speed-cassette-1/ , will almost certainly need a GS medium cage rear mech for 11-34.

fenix

There's no way your bike was sold with an 11-22 cassette unless you bought it second hand ?

More likely 11-28 ? But easy enough to count to be sure. Sometimes you can even see the number of teeth stamped onto the sprocket.

And you also need to know what you have on the front.

Possibly 52-36 looking at an old spec on line ?

You'll have to change the chain if you change the cassette anyway so is this a job for the LBS ?

Might be worth thinking of a compact chainset if you haven't got one.

spturton

Hi thanks for the replies.

Sorry - I'm not thinking of upgrading the cassette - but buying a new bike all together, I just have no idea what the ratios mean!

pblakeney

If you are looking at a new bike and are struggling on the hills then make sure that the new bike has a compact chainset (50/34) and a sprocket at the back with the biggest cog somewhere between 28 & 34. A 28 tooth sprocket will suffice for most routes but increase if you are regularly going up hills of 15%+.

arlowood

spturton said:

Hi thanks for the replies.

Sorry - I'm not thinking of upgrading the cassette - but buying a new bike all together, I just have no idea what the ratios mean!

The easiest way to look at it is by taking the number of teeth on your front chainring and divide that by the number of teeth on the cassette sprocket. So for example if you have a 50 tooth chainring matched to an 11 tooth rear sprocket the resulting calculation is 50/11= 4.5. So every complete revolution of the chainring turns the rear sprocket (and wheel) 4.5 times ie quite a hard gear to turn as you need a lot of power to get the rear wheel turning. If you have a 50 tooth matched to a 32 tooth sprocket on the rear the ratio is 50/32= 1.56. So every revolution of the chainring turns the sprocket/wheel 1.56 times; therefore an easier gear to manage as less power is needed to turn rear sprocket/wheel.

In summary then the lower the result of dividing the chainring teeth by the cassette sprocket teeth, the easier the gear is to manage and the better it is for climbing. As an example a compact chainset has a 34 inner ring. If you have a 32 sprocket as the largest at the rear then 34/32=1.06 so almost a 1:1 ratio and a very easy gear to turn for climbing. As an extreme example you could opt for a 11-36 rear cassette which would give you 0.94 ratio for the 34/36 combination so a much easier combo for climbing

pblakeney

Another point to consider is gaps in gears. The bigger the spread, the bigger the gaps. For example an 11-23 cassette has very little gaps between, an 11-36 will have big gaps.

joe_totale-2

spturton said:

Hi thanks for the replies.

Sorry - I'm not thinking of upgrading the cassette - but buying a new bike all together, I just have no idea what the ratios mean!

Given you could be spending a lot of money on a new bike, you should learn about gear ratios to help you buy the right thing.

Have a read of something like this:

https://www.yellowjersey.co.uk/the-draft/bike-gears-explained/

davep1

You have to look at the whole system, the cassette at the back and the crankset at the front.
My last bike was Campag equipped, it had a 53-39 crankset with an 12-25 cassette, 9 speed I think. These days, this would be seen as an old school set up for an experienced rider; if you were on the flat, or gentle gradients either up or down, the ratios of the cassette were quite close so there weren't big jumps making it easy to find the right gear to be in. Any steep climbs would see me grind to a halt, I would have to ride out of the saddle and force my way up. Going downhill I could pedal hard for as long as I had the bottle,, my legs didn't spin so fast I couldn't keep meaningful pressure on the pedals.

I gradually swapped the cassette from a 12-25 to a 12-27 then a 12-29, and each extra couple of teeth made steep climbs a bit easier, meaning I could stay in the saddle and spin a bit longer before standing.

The opposite of this setup is a compact chainset, 50-34 with say an 11-30 or bigger cassette. This is much better for climbing, you can keep your cadence up (which should be more efficient) for longer. Going fast downhill will see you spin out earlier, you'll be forced to coast sooner.

Generally changing a cassette is relatively cheap, chains and cassettes where quite quickly too, so you are more likely to have to replace them sooner. The size of the rear derailleur can limit what you can change the cassette to, although Shimano are known for being cautious with what they say works. Changing the crankset is big money.

A lot of modern bikes come with a mid-crankset, 52-36, often with an 11-32 cassette. I think it's a great compromise.

spturton

joe_totale-2 said:

spturton said:

Hi thanks for the replies.

Sorry - I'm not thinking of upgrading the cassette - but buying a new bike all together, I just have no idea what the ratios mean!

Given you could be spending a lot of money on a new bike, you should learn about gear ratios to help you buy the right thing.

Have a read of something like this:

https://www.yellowjersey.co.uk/the-draft/bike-gears-explained/

Thanks for this - it's proved really useful and I think I get the gist now.

spturton

fenix said:

There's no way your bike was sold with an 11-22 cassette unless you bought it second hand ?

More likely 11-28 ? But easy enough to count to be sure. Sometimes you can even see the number of teeth stamped onto the sprocket.

And you also need to know what you have on the front.

Possibly 52-36 looking at an old spec on line ?

You'll have to change the chain if you change the cassette anyway so is this a job for the LBS ?

Might be worth thinking of a compact chainset if you haven't got one.

I located the cassette information. 12-25 and 50-34. I'm simply not fit enough or strong enough to haul myself up winnats pass on that ratio (or any ratio to be fair).

By the look of new bikes in my price range - looks like 11-32 / 52-36 is the way to go.

fenix

Winnats pass is tough for anyone.

I'd definitely be looking at a compact chainset though.

Nobody's ever complained about having too low a gear and very few of us need a 52 X 12.

moonshine

Look for a compact chainset (50/34) paired to a 11-32 cassette

Ignore the 52/36 chainset idea if you are struggling with a 50/34 and 12-25 cassette. the 52/36 gives you is more bigger gears, when you want more smaller gears!

If you are really struggling, how about a gravel orientated GRX 2x11 setup? These are even lower geared than a compact at 48/31 this paired with an 11-32 or 11-36 gives many lower gears at the expense of big gears at the top end?

spturton

Cheers. By the sounds of things, it's going to be worth asking them to switchout for a compact set.

Reckon I'll buy in July and get them to switch out the cassette before sending.

Many thanks guys!

teisetrotter

It's pretty easy to get and change cassettes and chain-rings. I do it all the time. With a Compact 11-25 for normal work. A 11-29 for the hills. With a semi-compact 11-27 and 11-32. These are Campag ratios, not sure of Shimano ones but I'd assume very similar and cheaper.

amrushton

I would go 48 36 on the front or even 46 36. You will find you spend more time in the middle and rear of the cassette and gravity takes care of the downhill. Winnats pass? Stupid narrow road. Climbing out of Castleton behind the pub gets you to the same place at a shallower pitch

spturton

Thanks for everyone's advice. I've gone ahead and ordered the 2020 Supersix Evo Ultegra and got them to swap out the crankset (52/36) for a compact 50/34 crankset. Apparently I also needed to get a new bottom bracket to make is compatible.

One last (probably dumb) question. The bike comes with a 105 cassette. Am I right in thinking that's not going to make a difference and will be fine? I wouldn't need to stick an ultegra cassette on the back? The only difference is ultegra is just slightly better and lighter?

Thanks.

joe_totale-2

The only difference between a 105 and Ultegra cassette is a small weight difference. They function exactly the same and you'll never notice the difference.

It seems strange that they're swapping the bottom bracket out, they must be changing the Cannondale crankset for a Shimano one.

joe2019

105 cassette will be fine.

ibr17xvii

You shouldn't need a new BB if they're just swapping chainrings so if you're getting charged for that I'd be asking why.

As above they must be swapping he Cannondale SI Crankset for a Shimano one which seems unnecessary to me.

spturton

I wasn't charged for the bottom bracket. They tried to charge me for the bottom bracket and labour for swapping it out, despite building the bike prior to shipping to me which I pointed out.

I also asked them to do a part-x for ultegra crankset but they refused. I'll stick that on ebay and see if I get anything back for it.

Again, thanks for the help guys.

joe_totale-2

Sorry, double post

spturton

Bike arrived last week with a swapped over chainset - it's made scooting up hills much easier (easier than getting stronger legs anyway). Thanks for the advice guys.