Forum home Road cycling forum Road beginners

cassette? 28 up to 32?

Jerry185Jerry185 Posts: 143
edited July 2016 in Road beginners
Hi

looking for a possible cassette change as I've done a few sportives (and a bike camp), the last weekend saw me going OK up a steep hill, only to be overtaken by someone obviously 'wearing' a large granny cog.

Question is, and just thinking, why do most cassettes jump from a 28 right up to 32? Surely that's a 'struggle' to a 'spin-out' if that makes sense.
Why isn't 28-30 more popular?

Thanks

Posts

  • sungodsungod Posts: 13,208
    design spacing between cogs is driven by ratio and the limitation of how many will fit on a cassette

    at the high gear end, the smallest possible difference is 1, going 12->11 is a pretty big difference in effort, many people will never use the 11 except on descents

    the spacing on the higher gears is 1 as far across the cassette as possible, otherwise the difference in effort is too great

    at the other extreme, going from 28->30, a difference of 2, is a much smaller difference in effort, it's a 'waste' of a cog that could be better used to, say, avoid going 15-17, the lowest gear is there a last resort, going 28-32 is a more logical option
    my bike - faster than god's and twice as shiny
  • whoofwhoof Posts: 756
    It's because they are ratios.

    If you have a 10 speed cassette 11-32: 11-12-13-15-17-19-21-24-28-32
    & a compact 34- 50 chain-set it looks like a huge gear jump between 24 and 28 or 28 and 32.

    Putting numbers to the post above from 34/28 (31.8") to 34/32 (27.9") is a difference in gearing of 3.9 'inches.
    from 50/11 (119.7") to 50/12 (109.7") is a difference of 10 inches so 2 &1/2 times a bigger jump as above.

    In order to keep the jumps between gear to a minimum the difference in the number of cassette cogs change by one at the small end and then this gets wider as you move up the cassette

    http://www.bikecalc.com/gear_inches

    if you want a road cassette a 30 sprocket you can get a 12-30. If you want to go faster in 50/12 learn to pedal quickly rather than churn or get a 'standard' rather than compact chain-set and you can fit this 59t chain-ring.

    http://www.wiggle.co.uk/shimano-ultegra ... -cassette/

    http://www.spacycles.co.uk/m2b0s113p968 ... ter-57-59t
  • svettysvetty Posts: 1,904
    Jerry185 wrote:
    Hi

    looking for a possible cassette change as I've done a few sportives (and a bike camp), the last weekend saw me going OK up a steep hill, only to be overtaken by someone obviously 'wearing' a large granny cog.
    Thanks

    If he overtook you he was obviously putting out more watts per kilo than you were - that's the metric that fundamentally matters, not his gear ratio :)
    FFS! Harden up and grow a pair :D
  • Jerry185Jerry185 Posts: 143
    Hi Svetty

    no it was definitely the gear ratio, his rpm was way more than mine even tho he was overtaking. Think I've got the idea that a 32 is the best cog for long graded hill climbs
  • davebradswmbdavebradswmb Posts: 234
    Jerry185 wrote:
    Hi Svetty

    no it was definitely the gear ratio, his rpm was way more than mine even tho he was overtaking. Think I've got the idea that a 32 is the best cog for long graded hill climbs
    Get one then and see what difference it makes, I think you'll find Svetty is right :)
  • imposter2.0imposter2.0 Posts: 11,027
    Jerry185 wrote:
    Hi Svetty

    no it was definitely the gear ratio, his rpm was way more than mine even tho he was overtaking. Think I've got the idea that a 32 is the best cog for long graded hill climbs

    Svetty is right. He was going faster than you - ergo he was putting out more power. It's an actual law of physics.
  • davidofdavidof Posts: 2,382
    Jerry185 wrote:
    Hi Svetty

    no it was definitely the gear ratio, his rpm was way more than mine even tho he was overtaking. Think I've got the idea that a 32 is the best cog for long graded hill climbs

    That depends how efficiently you can spin, uphill and how much strength you have. I have a x32 but wouldn't use it over a whole climb, just for very steep sections which are too long to do out of the saddle (I'm talking 1000 meter climbs here), I generally try to stick in the 34x25 or 34x28 and around 70rpm as that is where I'm most efficient for climbing the typical 7 to 10% gradients around here. I would go slower on a x32 on those grades as I can't pedal at higher rpms efficiently.
  • Jerry185Jerry185 Posts: 143
    Thanks Davidof, that's the confirmation I was looking for and for the climbs I intend to do.
    Look, not being funny guys, but someone overtaking doesn't mean they're just more powerful in the same gear; but maybe efficient in a gear I don't have - that's why gears are there (e.g. trying to go up a 10% on the big ring might mean I have the same power, but will end with me face-splatting the tarmac). To reiterate, it was obvious from his much faster rpm he was on a bigger rear cog.
    The problem I have is having a perfectly decent alu bike but deciding whether to get a 30/32 with new chain and rear cage derailleur, or upgrade to a carbon.
    D's reply is exactly my strategy on hills, just needed to hear it on a forum.

    Cheers
  • imposter2.0imposter2.0 Posts: 11,027
    Jerry185 wrote:
    Thanks Davidof, that's the confirmation I was looking for and for the climbs I intend to do.
    Look, not being funny guys, but someone overtaking doesn't mean they're just more powerful in the same gear; but maybe efficient in a gear I don't have - that's why gears are there (e.g. trying to go up a 10% on the big ring might mean I have the same power, but will end with me face-splatting the tarmac). To reiterate, it was obvious from his much faster rpm he was on a bigger rear cog.
    The problem I have is having a perfectly decent alu bike but deciding whether to get a 30/32 with new chain and rear cage derailleur, or upgrade to a carbon.
    D's reply is exactly my strategy on hills, just needed to hear it on a forum.

    Cheers

    If you were only after confirmation bias, you should have said - and just because you happen to agree with Davidof, doesn't actually make either of you correct. Power is the rate at which energy is transferred, or the rate at which work is done. Regardless of gear, if someone passes you on a hill, they are putting out more watts/kg than you.
  • markhewitt1978markhewitt1978 Posts: 7,614
    Jerry185 wrote:
    Question is, and just thinking, why do most cassettes jump from a 28 right up to 32? Surely that's a 'struggle' to a 'spin-out' if that makes sense.
    Why isn't 28-30 more popular?

    I'm confused as to what you're actually asking here. I personally run 12-30 with a 50-34 chainset. I have no clue what you mean by 28-30.
  • ravey1981ravey1981 Posts: 1,111
    Jerry185 wrote:
    Thanks Davidof, that's the confirmation I was looking for and for the climbs I intend to do.
    Look, not being funny guys, but someone overtaking doesn't mean they're just more powerful in the same gear; but maybe efficient in a gear I don't have - that's why gears are there (e.g. trying to go up a 10% on the big ring might mean I have the same power, but will end with me face-splatting the tarmac). To reiterate, it was obvious from his much faster rpm he was on a bigger rear cog.
    The problem I have is having a perfectly decent alu bike but deciding whether to get a 30/32 with new chain and rear cage derailleur, or upgrade to a carbon.
    D's reply is exactly my strategy on hills, just needed to hear it on a forum.

    Cheers

    Why didn't you just pedal faster then? If you have more power than him you could take him easily.... :lol:
  • Jerry185Jerry185 Posts: 143
    Ravey

    appreciate your humour, at least yours was funny
  • shmoostershmooster Posts: 355
    To be fair cadence has an impact on power, try doing an ftp test at say 70rpm vs 90rpm and see if your power output is the same.
  • imposter2.0imposter2.0 Posts: 11,027
    shmooster wrote:
    To be fair cadence has an impact on power, try doing an ftp test at say 70rpm vs 90rpm and see if your power output is the same.

    Sorry, but that's overly-simplistic, to the point of being irrelevant. For the same gear ratio, then it stands to reason that power output would be higher at the higher cadence, obviously. But without the aerobic capacity (ie fitness) to sustain 90rpm for any length of time, it is a meaningless comparison. If higher FTP was simply a matter of just pedalling faster in the same gear, then we'd all do it and we'd all have massive FTP numbers.
  • t4tomot4tomo Posts: 2,643
    I think the overtaking rider was more powerful AND possibly had a more suitable gear for a steep hill.

    Jerry, if you are finding some hills tough and can't do a decent cadence (rpm) in your lowest gear, then yes a xx-30 or xx-32 cassette will help. (ideally xx=12 but they seem rarer than xx=11). with a 30 your rear mech should cope, with maybe a bit of adjustment to the limit screw, with a 32 your rear mech may need changing to a medium cage. you will also need a slightly longer chain, but you should start off a new cassette with a new chain anyway.

    I used to use a 12-25 and now have a 11-28 which I find much better for the steeper hills, not that it makes me any quicker up them per se, its just less tiring to sit and spin more than stand and grind.
    Bianchi Infinito CV
    Bianchi Via Nirone 7 Ultegra
    Brompton S Type
    Carrera Vengeance Ultimate Ltd
    Gary Fisher Aquila '98
    Front half of a Viking Saratoga Tandem
  • My bike (Cervelo R3) comes with 52/36 front rings and an 11-25 cassette.

    Coming from an MTB backround, I found the 36/25 gear pretty hard going for me. I started researching swapping to an 11-28 cassette and then thought why not go whole hog and fit the 11-32, longer cage mech and longer chain (the 11-32 DOES work on the short cage mech but you can't go near 52/28 or 52/32).

    So anyway, now I have the 11-32 and it all runs sweetly. However, since I have been getting fitter and riding more I have found I haven't been using the 32. Going up Box Hill after a 40 mile ride there and knackered legs, I went up in the 36/25.

    I'm still glad I've got the 32 option there though, just in case my legs give out on a steep hill.
  • shmoostershmooster Posts: 355
    Imposter wrote:

    Sorry, but that's overly-simplistic, to the point of being irrelevant.

    Simplistic yes, irrelevant no, you get more watts from spinning than grinding, within reason. Thats why we have gears after all :D

    The earlier posts implied the OP should be able to put out the same watts at a lower cadence and thats misleading and unfair.
  • imposter2.0imposter2.0 Posts: 11,027
    shmooster wrote:
    The earlier posts implied the OP should be able to put out the same watts at a lower cadence and thats misleading and unfair.

    I don't see any post which implied that. I see a few posts which implied that the other guy was probably fitter - which is correct.
  • To save time with all the waffling just bung on a 32 cassette. Got one on my climbing wheelset and running a short cage semi compact Ultegra with no problems. :D
  • shmoostershmooster Posts: 355
    Imposter wrote:
    Jerry185 wrote:
    Hi Svetty

    no it was definitely the gear ratio, his rpm was way more than mine

    He was going faster than you - ergo he was putting out more power. It's an actual law of physics.

    Power is pedal force x cadence, thats actual physics.

    And yes, i saw Davidof called out how efficient you are at spinning, I don't think the cadence has been mentioned but assuming the OP isnt spinning out a lower gear might help.
  • Jerry185Jerry185 Posts: 143
    Thanks all, think we've busted this now. Your help and assurance has been great
  • markhewitt1978markhewitt1978 Posts: 7,614
    So anyway, now I have the 11-32 and it all runs sweetly. However, since I have been getting fitter and riding more I have found I haven't been using the 32. Going up Box Hill after a 40 mile ride there and knackered legs, I went up in the 36/25.

    It's a short and gentle hill so that sounds about right.
Sign In or Register to comment.