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Changing chainring and gear ratios.

  • 05-07-2011 10:16PM
    #1
    CianRyan
    Registered Users, Registered Users 2 Posts: 14,730 ✭✭✭✭


    Hi all, yet another thread to fill my head with info.

    Today my chain was popping off at the front a lot so down I went to see what was wrong, seems one of the teeth is about half the length it should be and the chain is slipping right off every now and again in the highest gear (53/12) so obviously it's time for a change, which is quite annoying seeing as I've just bought the bike...

    Anyway, I'd like to try another ratio. I've found that 53/12 isn't always hard enough while I'm descending. I'm not exactly spinning in that gear but I'd like to feel like I could put more power into it then I can with this set up.
    I'd be happy to sacrifice climbing easily for more power in the highest gears. Right now I'm running 53-39(double) and 26-12 on the rear.

    So this is wear the questions start:
    • Given the ratio, what size to do reckon my RD(105) is?
    • What can I put on it to give me more power?
    • Can I go compact double?
    • Would that give me the power I'm looking for?
    • Since I'm changing the front chainrings, would it be worth changing the cassette?
    • My chain doesn't show sings of stretch but I was thinking I should probably change it while I'm doing everything else, would this be correct?

    A lot of questions but I am new to this after all.
    Both the FD and RD both seem to be fine so I won't be changing those right now.

    Thanks everyone,
    Cian.
    Tagged:


Comments

  • #2
    cdaly_
    Registered Users, Registered Users 2 Posts: 6,440 ✭✭✭cdaly_


    I'd say you should be looking at re-adjusting your FD. Chainrings are designed with a few short teeth to assist in gear changes.

    Regarding ratios, I reckon you're not pedalling fast enough. 53/12 @ 100rpm is 55.8kph and @ 120rpm it's 66.9kph. If you want a longer gear than that, change the cassette to an 11-25 or similar. A 53t chainring is pretty much the biggest standard ring to be had. A compact (50/34) will give you shorter gears, not longer.


  • #3
    CianRyan
    Registered Users, Registered Users 2 Posts: 14,730 ✭✭✭✭CianRyan


    I know that chainrings(CR) are designs with short teeth but this one seems like it's had quite a lot of wear. I bought the bike second hand, it's an 07 model and it's got the stock CR on it, I know time isn't an indication of how much wear something will have but 4 years is a long time and the bike is well used. The cassette has been changed since how ever, so I'd say they neglected the CR.

    Anyway... Would it be ok to swap straight to 11-25 and which size chain should I be buying?
    The cassette on the bike now is a 9 speed SRAM, would it be alright to switch straight to a 10 speed?
    I was looking at this 105 one.
    I'm getting a bit lost when it comes to the CR though. If I do end up changing the front, should I change both the 53 and 39?

    As regards to going faster, I guess I need to train more. :rolleyes::)

    Again, sorry for all the questions. I just want to be well educated before I make a purchase. :)


  • #4
    Vizzy
    Registered Users, Registered Users 2 Posts: 2,591 ✭✭✭Vizzy


    Cian,

    The RD is probably the standard length( i.e neither long or short) and you will get away with a 52/28 with that.
    If you are fitting an 11 or 12 to 27 you will probably get away with that with the 53 on the front.
    You might have to adjust the screws on the back of the RD( not the barrel adjuster,the screws that determine the travel of the RD,you will know which ones when you have a look) so that it will clear the cogs on the larger sprockets.
    Fit the cassette,put it in the lowest gear and you will nearly know by the look of the RD if the chain is too short
    With regard to moving from 9 speed to 10 you will also need to change shifters/brakes as well and possibly the FD as well( not 100% on this).
    If you just want to replace the large chainring you would probably be better to change the small one as well cos when you think about it the small one will probably have gotten more use than the large.
    Perhaps just one of the teeth is worn or broken ? In that case just replace the large ring.


  • #5
    CianRyan
    Registered Users, Registered Users 2 Posts: 14,730 ✭✭✭✭CianRyan


    Thanks!
    Well given I'd need to change the levers, I guess I'll stick with 9 speed. Any recommendations for a 9 speed cassette with that extra length?
    As said, I don't mind suffering a bit more in the hills, it's good for the legs anyway. :)

    I've never tried adjustments before, generally get the LBS to do it for me but I wouldn't be completely useless at this sort of thing. Is it worth having a go of this or should I get the LBS to fit them in case I cock it up?

    The big ring shows more signs of damage then the small one but I guess it's piece of mind to change it and upgrade while I'm at it.
    Still a bit lost with parts so any advice/links in that department would be hugely appreciated. :)


  • #6
    Vizzy
    Registered Users, Registered Users 2 Posts: 2,591 ✭✭✭Vizzy


    Did a quick look around of the major sites a few minutes ago(Wiggle,CRC etc) and they all seem to only do 12/26 or 11/25 in 9 speed cassettes
    If you are looking for more top speed then the 11/25 is the one to go for but you will suffer a bit on the climbs.
    You will need a cassette removal tool to take the old one off and tighten the new one up.
    Same with the chainset,you will need a special tool to "pull" the crank.
    If you are near a good bikeshop I would go in,explain what you want (i.e a higher top gear and a new chainset) and see what they have.If you have the tools it is a 1/2 hour job,if not you will do harm.
    Oh and bring the wallet for all the extra stuff you buy when you go in to the LBS:)


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  • #7
    cdaly_
    Registered Users, Registered Users 2 Posts: 6,440 ✭✭✭cdaly_


    If you're replacing both chainset and cassette, an new chain is probably needed also. A worn chain will accelerate wear on the cassette.


  • #8
    CianRyan
    Registered Users, Registered Users 2 Posts: 14,730 ✭✭✭✭CianRyan


    Thanks, lads. I'll have a wander over to the LBS and see what have and try and figure out the cost.
    This'll be after the holidays at this stage though... So broke atm.


  • #9
    doozerie
    Registered Users, Registered Users 2 Posts: 4,830 ✭✭✭doozerie


    I presume what you mean is that your chain is slipping on the big front ring? If so then the cause is most likely to be a worn chain and/or worn rear cassette - a single worn tooth on a chainring won't cause the chain to slip as the chain spans multiple teeth simultaneously. Chainrings typically last many years/miles (thousands) whereas the chain and cassette will wear out a lot sooner.

    So changing the chain and cassette may be all that is needed to solve the problem and of course you can change to a higher gear (an 11 tooth on the cassette) in the process should you wish. Personally I wouldn't change to a 53-11 gear unless I had the legs to comfortably spin a 53-12 on the flat (I don't) but it depends on personal taste and your riding style. From the point of view of general health of your joints it is preferable to spin a gear quickly (maybe in the region of 80 to 100rpm) rather than turn over a higher gear slowly as that stresses your joints more.


  • #10
    CianRyan
    Registered Users, Registered Users 2 Posts: 14,730 ✭✭✭✭CianRyan


    doozerie wrote: »
    I presume what you mean is that your chain is slipping on the big front ring? If so then the cause is most likely to be a worn chain and/or worn rear cassette - a single worn tooth on a chainring won't cause the chain to slip as the chain spans multiple teeth simultaneously. Chainrings typically last many years/miles (thousands) whereas the chain and cassette will wear out a lot sooner.

    So changing the chain and cassette may be all that is needed to solve the problem and of course you can change to a higher gear (an 11 tooth on the cassette) in the process should you wish. Personally I wouldn't change to a 53-11 gear unless I had the legs to comfortably spin a 53-12 on the flat (I don't) but it depends on personal taste and your riding style. From the point of view of general health of your joints it is preferable to spin a gear quickly (maybe in the region of 80 to 100rpm) rather than turn over a higher gear slowly as that stresses your joints more.


    I was thinking this too but I had a close look and it was very easy to identify the dodgy tooth as there is quite an audible "click" and I can see the chain popping off. If I continue to turn the cranks at this stage, the chain falls off the big ring, away from the small ring(towards the pedals).

    When I get up to speed I can spin 53/12 quite comfortably on the flat. I've never felt like I've need a bigger gear on the flat but the power is there* so I'd say the step up to 53/11 would suit me well.

    *I've been skateboarding, doing parkour and playing rugby for years but decided to switch to cycling recently enough, so even though I'm quite new to the sport my legs have always been quite strong.


  • #11
    Home:Ballyhoura
    Registered Users, Registered Users 2 Posts: 1,702 ✭✭✭Home:Ballyhoura


    CianRyan wrote: »
    When I get up to speed I can spin 53/12 quite comfortably on the flat

    Not long before we see you in the Tour de France so :)


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  • #12
    CianRyan
    Registered Users, Registered Users 2 Posts: 14,730 ✭✭✭✭CianRyan


    Home:Ballyhoura wrote: »
    Not long before we see you in the Tour de France so :)

    Me hole... I have the endurance of a 30 stone man.:P

    Spinning is a huge overstatement but I am quite comfortable in that gear.


  • #13
    doozerie
    Registered Users, Registered Users 2 Posts: 4,830 ✭✭✭doozerie


    CianRyan wrote: »
    I was thinking this too but I had a close look and it was very easy to identify the dodgy tooth as there is quite an audible "click" and I can see the chain popping off. If I continue to turn the cranks at this stage, the chain falls off the big ring, away from the small ring(towards the pedals).

    It certainly sounds like one of the chain or chainrings is worn out, maybe even both. It can be tricky to narrow down between the two though. You can measure the chain itself easily enough (some tips here) but gauging the level of wear of the chainring is trickier - if you have a new chain you can drape it round the ring and check it by eye (this describes it for cassettes but the principal for chainrings is the same). The ultimate test of the existing chainring is whether a new chain slips on it but it's a pain in the neck to have put on a new chain (and perhaps a new cassette too) only to find out at this stage that your chainring definitely needs replacing too.
    CianRyan wrote:
    When I get up to speed I can spin 53/12 quite comfortably on the flat. I've never felt like I've need a bigger gear on the flat but the power is there* so I'd say the step up to 53/11 would suit me well.

    *I've been skateboarding, doing parkour and playing rugby for years but decided to switch to cycling recently enough, so even though I'm quite new to the sport my legs have always been quite strong.

    It can be an easy trap to fall into to play to your own strengths by pushing a high gear at a low cadence when you have strong legs, and it can feel "right", but there is a danger that you are putting more strain on your joints than is healthy for them. I may well be teaching you to suck eggs here and apologies if so, but I'd suggest trying to gauge your cadence (a cadence sensor is the ideal option if you are happy to pay the money for one, otherwise just count your pedal revolutions for 30 seconds or 1 minute). There are various suggestions for the ideal cadence and they don't all agree but the ones I've seen are consistent in suggesting a figure in or around the 90rpm mark. If you are turning your legs more slowly then that then you are stressing your joints and while your legs may be happy to bear that strain it could cause you joint injuries in the long run.


  • #14
    CianRyan
    Registered Users, Registered Users 2 Posts: 14,730 ✭✭✭✭CianRyan


    doozerie wrote: »
    It certainly sounds like one of the chain or chainrings is worn out, maybe even both. It can be tricky to narrow down between the two though. You can measure the chain itself easily enough (some tips here) but gauging the level of wear of the chainring is trickier - if you have a new chain you can drape it round the ring and check it by eye (this describes it for cassettes but the principal for chainrings is the same). The ultimate test of the existing chainring is whether a new chain slips on it but it's a pain in the neck to have put on a new chain (and perhaps a new cassette too) only to find out at this stage that your chainring definitely needs replacing too.
    When I bought the bike, I was told that the chain was in a fine condition, this is after I asked if I should swap it so I wouldn't say the shop was having me for my money but I guess given I'm new to STI shifters and have a FD I could have sped up the aging process.
    Really, I'm I'm changing the cassette I'm definitely changing the chain and while I'm at it, it would probably be worth my while to get some new chainrings while I'm at it.

    As said before, the bikes about four years old and judging by the condition it was in when I bought it, I think neglect was a big part of it's life.
    Seemed to be a commuter, a hard ridden one.

    doozerie wrote: »
    It can be an easy trap to fall into to play to your own strengths by pushing a high gear at a low cadence when you have strong legs, and it can feel "right", but there is a danger that you are putting more strain on your joints than is healthy for them. I may well be teaching you to suck eggs here and apologies if so, but I'd suggest trying to gauge your cadence (a cadence sensor is the ideal option if you are happy to pay the money for one, otherwise just count your pedal revolutions for 30 seconds or 1 minute). There are various suggestions for the ideal cadence and they don't all agree but the ones I've seen are consistent in suggesting a figure in or around the 90rpm mark. If you are turning your legs more slowly then that then you are stressing your joints and while your legs may be happy to bear that strain it could cause you joint injuries in the long run.

    I love getting advice from someone more experienced then myself, no need for an apology!
    At the moment, a cadence sensor is out of the question(21st is coming up in a few months, turbo trainer and edge 500+goodies are on the list!! :D) so I'll try to see what kind of cadence I generally have.
    I do think I'm more inclined to push a bigger gear as I find I loose the legs a lot quicker if I'm spinning. I also find it hard not to over spin and loose rhythm, this will all be sorted in time though I guess.

    There's a history of knee issues in my family, my dad had to give up senior county football and hurling because of it, so I should definitely be taking care of my joints.
    Seeing a sports physio is something that's on my list but I don't know who to be going to or how much it will cost so it's been on the long finger for a while now.


  • #15
    kumate_champ07
    Closed Accounts Posts: 7,150 ✭✭✭kumate_champ07


    I was the same, liked to push a large gear because Ive very strong legs but you'll slowly wear out your knee joints, might not feel it now but it will come. I ride 48:19 fixed gear, when I need speed I go up to 180rpm on long flats or declines which is around 58km/h. I do track racing and for my race gear I use 49:16 which is a bit low compared to other racers but I enjoy spinning now. Going to 48:15 next to give me more speed for sprints but Id never dream of using 52:12


  • #16
    CianRyan
    Registered Users, Registered Users 2 Posts: 14,730 ✭✭✭✭CianRyan


    There's another thing I've been thinking about, I'd love to build a track bike sometime, probably after my holidays and probably after I g a job again.
    I was thinking of this the other day and realised, I'd have no idea what ratio to use!
    There's a lot I've to learn, that's for sure...

    I know people are saying that pushing a big gear is bad for the knees but I'd still like to have the 11tooth cog on my cassette, even if it is just for rare use on a decent, I'd love to have that option. Sure, there'll be 8 other gears for me to choose from on the cassette so I'll get used to spinning in those.


  • #17
    cdaly_
    Registered Users, Registered Users 2 Posts: 6,440 ✭✭✭cdaly_


    I used to think that way too. Then I learned to spin...

    I feel uncomfortable below about 80rpm and my best power seems to be between 90 and 100rpm. Top gear for me is 52x13 and I only use that on descents. On the flat I'll be using 42x16 or 42x15 at around 30-35kph.


  • #18
    blorg
    Registered Users, Registered Users 2 Posts: 15,995 ✭✭✭✭blorg


    As others have said, you need to learn to pedal faster. H:B's comment is spot on; pro riders in the Tour will often have 53-12 as their biggest gear. You do not need 53-11, there is no question. Descending you will be limited by your aero tuck and cornering skills, not your lack of an 11T.

    Getting an 11T is going to do nothing other than reinforce and worsen your existing bad technique; if anything you should be looking at getting an easier top gear to force you into spinning. Ideally you should be comfortable maintaining 90-100RPM indefinitely (for several hours over a spin) and be able to go up to say 120RPM without bouncing all over the saddle.

    I have been there myself, by the way, about ten years ago I thought I needed higher gearing also.


  • #19
    CianRyan
    Registered Users, Registered Users 2 Posts: 14,730 ✭✭✭✭CianRyan


    Right, having read everything I've decided not to change my cassette and upon bringing my bike to the shop, one of the teeth on the big ring was bent outwards. For now, we've just bent it back into shape but I will be changing it as soon as I can afford to do so.

    I've been working on my technique and really, I think next on my last (after overly stylish shades) is definitely going to be some proper shoes and the move to clipless.
    Spinning is very warning on the legs, I need to train a LOT more. :D

    Would beginner spins with clubs ever go over technique or is this something you're supposed to have down at that stage?

    And last question, any off bike exercises I can do to help with spinning?

    Learning, learning, learning! :)


  • #20
    blorg
    Registered Users, Registered Users 2 Posts: 15,995 ✭✭✭✭blorg


    Yes, bike clubs will be helpful on beginner spins and don't expect you to know these things.

    The key thing with spinning is to practice doing it. Get something that displays your cadence and just try to spin faster, and keep it up for a period. Keep the same speed as you would mashing by going into an easier gear. It is actually LESS taxing on your leg muscles and you will be less likely to suffer from tired/sore legs.

    Personally I massively improved my spinning by riding a fixie with a relatively easy gear ratio (46/17.) This gives you no option but to spin, particularly when going downhill.


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