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Chain ring and Cog advice

Skippy2309Skippy2309 Posts: 426
edited January 2010 in The workshop
So i took my bike out yesterday (rides like a dream) problem is I am quite a bit a stronger then expected and was spinning out (maybe over 140rpm it was uncomfortable) on the flats and hills have been taken seated and spinning at around 90rpm... it felt like I was running a tiny gear.

bare in mind I am either running SS or Fixed..... I am thinking of upping the gears a bit.

Currently running a 48/16 (fixed and freewheel), I am thinking of either upping the front chainring (50/52) or reducing the back (12/14) what is easier and what will give the better increase in performance.

How do I measure the bolt pattern size? what tools will I need to change these over?

Update
found on Sheldon brown that a 48/13 gives me 34.6mph where as a 52/16 gives me 30.5mph although a 52/13 gets it upto 37.5mph - so a smaller ring on the back is better.
FCN: 5/6 Fixed Gear (quite rapid) in normal clothes and clips :D

Cannondale CAAD9 / Mongoose Maurice (heavily modified)

Posts

  • redveeredvee Posts: 11,920
    Skippy2309 wrote:

    How do I measure the bolt pattern size? what tools will I need to change these over?

    There are two ways of measuring the BCD of a chainring. With 4 hole chainrings it is litterally straight across the ring from the centre of one hole to the centre of opposing hole, I find it easier to measure from the edge of one hole to the same edge of the opposing hole. There is another method of measuring from one hole to the next which I've seen on sheldon's pages somewhere.
    The tools needed are 5mm allen key and chainring spanner. Some chainring bolts are now coming through with Torx fittings.
    I've added a signature to prove it is still possible.
  • mmacavitymmacavity Posts: 781
    Skippy2309 wrote:
    upto 37.5mph - so a smaller ring on the back is better.


    All the best for your World Hour Record attempt:

    http://vimeo.com/8417074
    http://www.bikecult.com/bikecultbook/sp ... sHour.html
  • lol no chance of doing the hour,

    just want a decent gear so that i do not spin out on the flats. I was riding 48/14 on my mountain bike and it was comfortable, so going to go for a 48/13 on my fixed gear.


    What can I say I got a need for speed :D
    FCN: 5/6 Fixed Gear (quite rapid) in normal clothes and clips :D

    Cannondale CAAD9 / Mongoose Maurice (heavily modified)
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