Advertise on Bikeforums.net



User Tag List

Results 1 to 12 of 12

Thread: Gear Ratio

  1. #1
    Junior Member
    Join Date
    Nov 2013
    Posts
    10
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Gear Ratio

    I am rebuilding an old road bike (new to me) and am about to put on a new chain. I was doing the calculation to see the length of chain needed and got to thinking maybe the current gear ratio is not right for me and I should address that before cutting down the chain. The chain rings are 52/42T and the 6-speed freewheel is 13-24T.

    This is my first bike since I was a kid and got the bike to ride for recreation at a pretty leisurely pace. I'd like to use the bike in somewhat hilly (and scenic!) areas, am in my mid-twenties, and would consider myself to be in average shape. Is a 42:24 gear ratio low enough for any climb I'll ever face or should I opt for a different freewheel? Again, I'm not looking to power my way up any hills -- just want to make sure I'll be able to climb hills period.

  2. #2
    Catching Smallmouth BradH's Avatar
    Join Date
    Oct 2013
    Location
    In a boat
    My Bikes
    1994 Trek 930 Singletrack, 1990 Specialized Sirrus Triple, 1985 Trek 460, 2005 Lemond Tourmalet, 1984 Schwinn LeTour 'Luxe, 1988 Trek 400T, 1985 Trek 4??, 1997 Lemond Zurich, 1993 Diamond Back Apex
    Posts
    128
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    I have a 52/42 on my '85 trek 460. I have ridden it with a 14-23 and a 12-28 7 speed cassette out back (newer wheels & hubs). The 12-28 is much better.
    Internet Forums. Making simple tasks complicated since 1995.

  3. #3
    Junior Member
    Join Date
    Nov 2013
    Posts
    10
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by BradH View Post
    I have a 52/42 on my '85 trek 460. I have ridden it with a 14-23 and a 12-28 7 speed cassette out back (newer wheels & hubs). The 12-28 is much better.
    Did you have any trouble with the 12-28T freewheel and the rear derailleur or was there adequate clearance? What group set did you replace the freewheel on? Thanks!

  4. #4
    Have bike, will travel Barrettscv's Avatar
    Join Date
    Feb 2006
    Location
    Windy City
    My Bikes
    A road bike for every purpose
    Posts
    9,056
    Mentioned
    3 Post(s)
    Tagged
    0 Thread(s)
    You might consider this http://store.velo-orange.com/index.p...et-34x48t.html

    The smaller 34t inner chainring will provide a much greater improvement in climbing range (about 20%) than changing from a 24 to a 28 large cog on the freewheel (a 14% change). You existing derailleurs will work fine with this crankset.
    Last edited by Barrettscv; 01-21-14 at 02:17 PM.
    2014 Trek DS.1: "Viaggiatore" A do-it-all bike that is waiting in Italy
    2012 Pedal Force CG2: "Secolo Bicicletta" the modern carbon fiber road bike
    2012 Pedal Force CX2: "Carbone CX" the carbon fiber CX bike
    2010 Origin 8 CX 700: "Servizio Grave" Monstercross/29er bike
    1997 Simoncini Special Cyclocross: "Little Simon" lugged Columbus steel CX bike
    1987 Serotta Nova Special X: "Azzurri" The retro Columbus SPX steel road bike

  5. #5
    Have bike, will travel Barrettscv's Avatar
    Join Date
    Feb 2006
    Location
    Windy City
    My Bikes
    A road bike for every purpose
    Posts
    9,056
    Mentioned
    3 Post(s)
    Tagged
    0 Thread(s)
    I'm going to move this to the Mechanics Forum where it will find a larger pool of mechanical experts.
    2014 Trek DS.1: "Viaggiatore" A do-it-all bike that is waiting in Italy
    2012 Pedal Force CG2: "Secolo Bicicletta" the modern carbon fiber road bike
    2012 Pedal Force CX2: "Carbone CX" the carbon fiber CX bike
    2010 Origin 8 CX 700: "Servizio Grave" Monstercross/29er bike
    1997 Simoncini Special Cyclocross: "Little Simon" lugged Columbus steel CX bike
    1987 Serotta Nova Special X: "Azzurri" The retro Columbus SPX steel road bike

  6. #6
    Senior Member Bill Kapaun's Avatar
    Join Date
    Feb 2007
    Location
    Mid Willamette Valley, Orygun
    My Bikes
    86 RockHopper,2008 Specialized Globe. Both upgraded to 9 speeds.
    Posts
    7,050
    Mentioned
    3 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Barrettscv View Post
    You might consider this http://store.velo-orange.com/index.p...et-34x48t.html

    The smaller 34t inner chainring will provide a much greater improvement in climbing range (about 20%) than changing from a 24 to a 28 large cog on the freewheel (a 14% change). You existing derailleurs will work fine with this crankset.
    Much better to spend $100 for a crank set (and maybe more for a new BB) than $15 for a freewheel!
    http://www.amazon.com/Shimano-MF-TZ2.../dp/B003EQ71QI

    Sarcasm off.

  7. #7
    Senior Member
    Join Date
    Apr 2009
    Location
    New Rochelle, NY
    My Bikes
    too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter
    Posts
    21,215
    Mentioned
    50 Post(s)
    Tagged
    1 Thread(s)
    42/24 isn't going to cut it in hills for any but seriously strong riders. Buy yourself a wider range freewheel for starters, but even that may not be enough.

    BTW- there's never a problem with a chain cut to Maximum length. Loop the 42/24 combination through the derailleur and take up slack until the idler cage moves off the dead stop. That's the longest chain length that will work in all gears, and will leave room for a larger freewheel later.
    FB
    Chain-L site

    An ounce of diagnosis is worth a pound of cure.

    “Never argue with an idiot. He will only bring you down to his level and beat you with experience.”, George Carlin

    “One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN

    WARNING, I'm from New York. Thin skinned people should maintain safe distance.

  8. #8
    Senior Member
    Join Date
    Feb 2005
    Location
    Oklahoma
    My Bikes
    Trek 5500, Colnago C-50
    Posts
    9,123
    Mentioned
    2 Post(s)
    Tagged
    0 Thread(s)
    You can probably replace the 42 inner chainring with a 39 or 39 (assuming a 130 BCD), and also replace the freewheel with a 12-28 or similar. See sheldonbrown.com for how to measure BCD.

  9. #9
    Have bike, will travel Barrettscv's Avatar
    Join Date
    Feb 2006
    Location
    Windy City
    My Bikes
    A road bike for every purpose
    Posts
    9,056
    Mentioned
    3 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Bill Kapaun View Post
    Much better to spend $100 for a crank set (and maybe more for a new BB) than $15 for a freewheel!
    http://www.amazon.com/Shimano-MF-TZ2.../dp/B003EQ71QI

    Sarcasm off.
    Price is not the only issue, it may not be a primary issue. The larger cog size will also create bigger jumps between cogs and some rear derailleurs can't fit a 28t cog.

    The owner needs to know his options.
    Last edited by Barrettscv; 01-21-14 at 02:55 PM.
    2014 Trek DS.1: "Viaggiatore" A do-it-all bike that is waiting in Italy
    2012 Pedal Force CG2: "Secolo Bicicletta" the modern carbon fiber road bike
    2012 Pedal Force CX2: "Carbone CX" the carbon fiber CX bike
    2010 Origin 8 CX 700: "Servizio Grave" Monstercross/29er bike
    1997 Simoncini Special Cyclocross: "Little Simon" lugged Columbus steel CX bike
    1987 Serotta Nova Special X: "Azzurri" The retro Columbus SPX steel road bike

  10. #10
    Mechanic/Tourist
    Join Date
    Apr 2007
    Location
    Syracuse, NY
    My Bikes
    2008 Novara Randonee - love it. Would have more bikes if I had time to ride them all. Previous bikes: 1968 Motobecane Mirage, 1972 Moto Grand Jubilee (my fav), Jackson Rake 16, 1983 C'dale ST500.
    Posts
    5,040
    Mentioned
    5 Post(s)
    Tagged
    0 Thread(s)
    The 28 tooth low is the minimum I would suggest you consider. There's no way to tell if that's sufficient, as "average shape" means little when it comes to cycling. The problem is that we don't know if your derailleur will handle the 28 tooth cog. It's not "clearance" but rather "capacity" that is the issue. You need to find out what model of derailleur you have, or at least take a picture (from the side, at the level of the derailleur). If the bike is friction shift then changing both derailleur and freewheel is still not that expensive, and you can go larger than 28 teeth. But even a 42/34 may not be low enough for "any hill" you may encounter.

    I would not recommend any chainwheel upgrades without knowing more about the bike, as you may end up putting in much more money than is advisable.
    Last edited by cny-bikeman; 01-21-14 at 03:28 PM.
    There's no such thing as a routine repair.

    Don't tell me what "should" be - either it is, it isn't, or do something about it.

    If you think I'm being blunt take it as a compliment - if I thought you were too weak to handle the truth or a strong opinion I would not bother.

    Please take the time to post clearly so we can answer quickly. All lowercase and multiple typos makes for a hard read. Thanks!

  11. #11
    Catching Smallmouth BradH's Avatar
    Join Date
    Oct 2013
    Location
    In a boat
    My Bikes
    1994 Trek 930 Singletrack, 1990 Specialized Sirrus Triple, 1985 Trek 460, 2005 Lemond Tourmalet, 1984 Schwinn LeTour 'Luxe, 1988 Trek 400T, 1985 Trek 4??, 1997 Lemond Zurich, 1993 Diamond Back Apex
    Posts
    128
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by laserspeed View Post
    Did you have any trouble with the 12-28T freewheel and the rear derailleur or was there adequate clearance? What group set did you replace the freewheel on? Thanks!
    Suntour Cyclone II derailleurs. No issues. It will be better than what you have and a 14-28 costs about $15. A good place to start.
    Internet Forums. Making simple tasks complicated since 1995.

  12. #12
    Junior Member
    Join Date
    Nov 2013
    Posts
    10
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by FBinNY View Post
    42/24 isn't going to cut it in hills for any but seriously strong riders. Buy yourself a wider range freewheel for starters, but even that may not be enough.

    BTW- there's never a problem with a chain cut to Maximum length. Loop the 42/24 combination through the derailleur and take up slack until the idler cage moves off the dead stop. That's the longest chain length that will work in all gears, and will leave room for a larger freewheel later.
    I sort of got the sense that this would be the case after perusing some bike recommendation threads (that a 42/24 gear ratio would be way too aggressive for me) but didn't have any point of reference since I haven't owned a bike in years. I like the flexibility permitted with this idea!


    Quote Originally Posted by cny-bikeman View Post
    The 28 tooth low is the minimum I would suggest you consider. There's no way to tell if that's sufficient, as "average shape" means little when it comes to cycling. The problem is that we don't know if your derailleur will handle the 28 tooth cog. It's not "clearance" but rather "capacity" that is the issue. You need to find out what model of derailleur you have, or at least take a picture (from the side, at the level of the derailleur). If the bike is friction shift then changing both derailleur and freewheel is still not that expensive, and you can go larger than 28 teeth. But even a 42/34 may not be low enough for "any hill" you may encounter.

    I would not recommend any chainwheel upgrades without knowing more about the bike, as you may end up putting in much more money than is advisable.
    This is the rear derailleur. According to this website, the max cog size permissible is one with 28T -- that answers the freewheel question. The bike has friction shifters but can switch to indexing by turning a little pin and uses this (1050) group set.


    Quote Originally Posted by Barrettscv View Post
    You might consider this http://store.velo-orange.com/index.p...et-34x48t.html

    The smaller 34t inner chainring will provide a much greater improvement in climbing range (about 20%) than changing from a 24 to a 28 large cog on the freewheel (a 14% change). You existing derailleurs will work fine with this crankset.
    Quote Originally Posted by Bill Kapaun View Post
    Much better to spend $100 for a crank set (and maybe more for a new BB) than $15 for a freewheel!
    http://www.amazon.com/Shimano-MF-TZ2.../dp/B003EQ71QI

    Sarcasm off.
    Quote Originally Posted by Al1943 View Post
    You can probably replace the 42 inner chainring with a 39 or 39 (assuming a 130 BCD), and also replace the freewheel with a 12-28 or similar. See sheldonbrown.com for how to measure BCD.
    I measured the BCD to be 130 mm (77mm between two bolts c-c on a 5 bolt system). After hearing that a 42/28 ratio still might not cut it I am definitely interested in replacing the smaller chain ring but as Bill alluded to, price is definitely a factor. I do want a bike that is efficient but at the end of the day it is just for recreational rides so really it'll do its job just fine with any configuration really. If I can make it a bit easier on the cheap then I'll go for it. Thanks for all of the suggestions I've got some homework to do!

    EDIT: I forgot to add that I have "Biopace" chain rings that are not perfectly circular. Would it be okay to keep the 52T Biopace chain ring and use a perfectly circular 39T (or other) chain ring?
    Last edited by laserspeed; 01-21-14 at 05:00 PM.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •