Results 1 to 11 of 11
  1. #1
    mtbr member
    Reputation: MudKatt's Avatar
    Join Date
    Apr 2012
    Posts
    17

    Chainring upgrade.. how much larger should I get

    I have an old white ind crankset ( made in japan ) with sugino css iii rings on it.
    20-32-42

    I am running out of gear so I am thinking of going to a 46 or 48T large ring up front.

    I called white ind up and they said I needed a 94mm BCD compact drive.

    How much more gear should I get? Loads of room for a bigger gear.. I can move the derailleur up and plenty of clearance to the chainstay.

  2. #2
    mtbr member
    Reputation:
    Join Date
    May 2006
    Posts
    11,141
    I know a 46 tooth works well...not sure about a 48 tooth on a MTB FD. Also not sure about the RD being big enough for that amount of chain growth

  3. #3
    mtbr member
    Reputation:
    Join Date
    Oct 2009
    Posts
    225
    42x11cadence 90 = 27,... mph. Too slow?

  4. #4
    mtbr member
    Reputation: MudKatt's Avatar
    Join Date
    Apr 2012
    Posts
    17
    Yes it's too slow best I have gotten out of it is 24 with a tail wind on level ground. Downhill about 32

  5. #5
    Nouveau Retrogrouch SuperModerator
    Reputation: shiggy's Avatar
    Join Date
    Dec 1998
    Posts
    47,824
    Quote Originally Posted by MudKatt View Post
    Yes it's too slow best I have gotten out of it is 24 with a tail wind on level ground. Downhill about 32
    No matter what you put on, you still need to be able to turn it over to go faster. If you top out at 24mph on the flats with the 42T, you are not likely to go any faster with a bigger gear.
    mtbtires.com
    The trouble with common sense is it is no longer common

  6. #6
    mtbr member
    Reputation:
    Join Date
    Oct 2009
    Posts
    225
    Quote Originally Posted by MudKatt View Post
    Yes it's too slow best I have gotten out of it is 24 with a tail wind on level ground. Downhill about 32
    Power makes you faster not gears. You do not run out of gears you just pedal too slow.

  7. #7
    mtbr member
    Reputation: MudKatt's Avatar
    Join Date
    Apr 2012
    Posts
    17
    I ride everyday and my top speed is 29 according to my bike comp which could be off a mph. I have alot of uphills and downhills and max out on gear on downhills. Some very long long streches of downhill that I would like to go faster on.This area has very few flat sections. It's either up or down unless you are inbetween hills ... maybe an 1/8 mile

  8. #8
    mtbr member
    Reputation:
    Join Date
    Nov 2011
    Posts
    2,059
    Front derailleur probably has a capacity of 22 teeth so you won't be keeping the 20 tooth granny.
    42X11 @90 rpm=27 mph
    46X11 @90 rpm=29.5 mph
    48X11 @90 rpm=30.7 mph

    gear/speed calculator
    Bicycle Bike Gear Ratio Speed and Cadence Calculator

  9. #9
    mtbr member
    Reputation: MudKatt's Avatar
    Join Date
    Apr 2012
    Posts
    17
    According to Mike Sherman gear chart with my 26 inch x 2.1 tires and 42 to 11 gears, I would have to crank out 100 rpm for 30mph

    I would be looking to have a 26 capacity derailleur with a 46T ring. I wouldn't mind changing out the derailleur as it is old and beat. I was thinking of doing that anyway soon.

    46T might be the best way to go to get a couple MPH more.

  10. #10
    Nouveau Retrogrouch SuperModerator
    Reputation: shiggy's Avatar
    Join Date
    Dec 1998
    Posts
    47,824
    Quote Originally Posted by MudKatt View Post
    According to Mike Sherman gear chart with my 26 inch x 2.1 tires and 42 to 11 gears, I would have to crank out 100 rpm for 30mph

    I would be looking to have a 26 capacity derailleur with a 46T ring. I wouldn't mind changing out the derailleur as it is old and beat. I was thinking of doing that anyway soon.

    46T might be the best way to go to get a couple MPH more.
    Work on your spin. An additional 10rpm is also worth a couple of miles per hour. 100rpm is not an unusually high cadence. I can hold it for 3-4 hours at a time.

    I use a 36x11 top gear on my 26" wheel bikes. Pedaling past 35mph on the downhills is common (~140rpm).
    Last edited by shiggy; 09-17-2012 at 07:44 PM.
    mtbtires.com
    The trouble with common sense is it is no longer common

  11. #11
    mtbr member
    Reputation:
    Join Date
    May 2006
    Posts
    11,141
    Quote Originally Posted by MudKatt View Post
    According to Mike Sherman gear chart with my 26 inch x 2.1 tires and 42 to 11 gears, I would have to crank out 100 rpm for 30mph

    I would be looking to have a 26 capacity derailleur with a 46T ring. I wouldn't mind changing out the derailleur as it is old and beat. I was thinking of doing that anyway soon.

    46T might be the best way to go to get a couple MPH more.
    Yup go for the bigger chain ring.....that way you can go really fast downhill and with the wind....

    Plus 60 km is easily maintainable for many km around here...

    If you want to spin or learn how to spin faster.....guess what you can always down shift...

    I want at least two gears above where I spin out on flat pavement, or power out...

    Right now I can sprint about 52 kph for only 1 km.

Posting Permissions

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