Chainring size.

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Willam

Senior Member
Need to change a few parts, cassette, chain, fD and large chainring.

Looking at the price of a large chainring, at around £20, seems to make sense to change the whole set at £51, just wondering if going to a 48/36/26 from a 44/32/22 would work without to many issues as I find myself on the large chainring/small cog quite a lot.

I ride a GT avalanche for commuting to work.

Thanks
 

Sharky

Guru
Location
Kent
Can you replace the cassette with one that has smaller sprockets? The proposed chainwheel, will just shift the range up by up by approx one tooth difference on the cassette.
 

Ajax Bay

Guru
Location
East Devon
Rather than replacing the 3 chainwheels, depending what quality of crankset you have at present (XCT302?), you might find it economic to replace the whole crankset with a 48-36-26 combo. If you have an 11-32 cassette already there's no scope there for increased top gearing.
 

Gravity Aided

Legendary Member
Location
Land of Lincoln
You may also have to raise your front derailleur just a wee bit, and take up the slack in your cabling to get the same performance from the FD as before, and avoid striking the large chainring. Shouldn't be any real issues beside an extra link, as @Smokin Joe has already said, and the larger crankset sounds like it may suit your riding better anyway, as you are already mostly at the top end of that smaller crankset.
 
OP
OP
Willam

Willam

Senior Member
Rather than replacing the 3 chainwheels, depending what quality of crankset you have at present (XCT302?), you might find it economic to replace the whole crankset with a 48-36-26 combo. If you have an 11-32 cassette already there's no scope there for increased top gearing.

yeah sorry that is what I meant, the crankset is £51, where as the chainrings are around £20/£10 each, and yes it's a 11-32 cassette

this is the crankset http://www.wiggle.co.uk/shimano-fc-m590-deore-9-speed-483626t-triple-chainset/
 

Sharky

Guru
Location
Kent
Hi @Willam i get bewildered sometimes by the combinations that you can now get. But have you studied the gear tables to see the ratios you are getting with each chain ring?
With your original sizes, you have ranges -
22:18" to 52"
32: 26" to 76"
44: 36" to 105"

As you can see on pure "maths", the middle ring is completely redundant. If you establish which ratios you really need, you might find a double gives you better options, or if you never need the really small gears, then a more compact cassette might put the usable ratios on the rings that you want.
 
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What is the small cog, 11 or 12. A 44x11 at 90rpm is 27mph and 44x12 is 24mph. If you're approaching those speeds then change it, otherwise pedal faster (26inch wheels assumed, otherwise it's faster)
 
OP
OP
Willam

Willam

Senior Member
Hi @Willam i get bewildered sometimes by the combinations that you can now get. But have you studied the gear tables to see the ratios you are getting with each chain ring?
With your original sizes, you have ranges -
22:18" to 52"
32: 26" to 76"
44: 36" to 105"

As you can see on pure "maths", the middle ring is completely redundant. If you establish which ratios you really need, you might find a double gives you better options, or if you never need the really small gears, then a more compact cassette might put the usable ratios on the rings that you want.

yeah I find I never use the middle chainring.

To be honest, ratios go right over my head, I did consider going to 1 chainring but was unable to find a single crankset at a reasonable price, I know I can remove chainrings but I guess I'm thinking if it's already on the crank why remove it...I do hate the idea of having stuff on the bike I don't use.

If anyone has a recommendation of a single crankset I would like to take a look.
 
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OP
OP
Willam

Willam

Senior Member
What is the small cog, 11 or 12. A 44x11 at 90rpm is 27mph and 44x12 is 24mph. If you're approaching those speeds then change it, otherwise pedal faster (26inch wheels assumed, otherwise it's faster)

it's 11, those speeds sound quite high? I can't be reaching those speeds can I? or I would be happy? I do find I get pasted all the time by others even when I'm in top gear I guess I need to buy a cycle computer, as I have no idea of my rpm.

I do find though I prefer lower rpm and using more muscle power.
 

Sharky

Guru
Location
Kent
yeah I find I never use the middle chainring.

If anyone has a recommendation of a single crankset I would like to take a look.

If thinking about a single chainring with gears, have a look at the narrow-wide chainrings (e.g. Raceface). But the variation in chain length from the 11 to 32 is quite a lot to be absorbed by the rear mech, but you can prove this with your current set up before you make the changes. The advantages of the narrow-wide are that it helps to keep the chain from coming off. Be aware of the BCD if buying new rings.
 
it's 11, those speeds sound quite high? I can't be reaching those speeds can I? or I would be happy? I do find I get pasted all the time by others even when I'm in top gear I guess I need to buy a cycle computer, as I have no idea of my rpm.

I do find though I prefer lower rpm and using more muscle power.
Well we all have our own natural cadence, there's no right or wrong but you don't want to pedal too slow it's not as efficient and is a bit harder on the knees. You can simply count how many times one knee comes up in 15 secs and multiply by 4 for your cadence. As very much a rough guide, below 70rpm on the flat is low. I personally would be using gears that give me 80 or 90rpm on the flat.
 

Ajax Bay

Guru
Location
East Devon
OP Question: "just wondering if going to a 48/36/26 from a 44/32/22 would work without to many issues"
Fact: OP wants longer top gear so he can go faster when road, decline and wind allows.
Fact: He already has an 11-32 cassette and an RD which is handling the 32t and the 21+22 capacity requirement.
Fact: His current large chainwheel is a 44t
Fact: He has a BB and an FD for a triple.
Assumptions: Don't want to have to change the BB (so advice to try a double compact or a single is perfectly reasonable but suggest redundant). Not worth replacing the 3 chainwheels separately (see discussion above) as opposed to full replacement of crankset.
Recommended action: Go ahead and replace the crankset with the Deore the OP linked to http://www.wiggle.co.uk/shimano-fc-m590-deore-9-speed-483626t-triple-chainset/. first checking its compatibility with the existing BB (which I haven't done) or another 48-36-26 crankset that does (fit the BB). FD will probably be OK but may (will) need raising slightly. New chain length will need calculation (one inch = 2 links more probably).
OP - hope that helps.
 
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