Update chainring from 53/42 to 53/39

Discussion in 'Cycling Equipment' started by portlester, Feb 1, 2008.

  1. portlester

    portlester New Member

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    Hi guys

    Long time lurker but first time poster.

    I have recently got on the bike after some 10 years or so off it (apart from the odd false start). Until I know I am going to keep riding I am sticking to my old bike from the early 90's a Shogun Team Issue (a Shimano Ultegra 600 7spd).

    Been spending some time of late in the saddle so fitness etc is improving, however I still find it a bit of challenge to get up some of the hills (& I was never much of a climber back in my bike rider days when I was fit & young). My goal at the moment is to do the 145km Great Ocean & Otway Classic in mid March which has quite a few hills in it.

    My question is if I updated from the current 53/42 chain ring to a 53/39, will I find a large amount of difference getting up the hills? Or would I be better off persisting with the current setup, get fitter/stronger & then absolutely fly when I eventually update to a new bike in 8 months or so :).

    Finally if I do update, do I need to get a complete chainset or am I able to just replace the current 42 with a 39?

    many thanks
    portlester
     
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  2. Fignon le Grand

    Fignon le Grand New Member

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    Changing the chainrings would certainly help a bit, you can keep a better cadence with a 39 rather than a 42 so you will be able to stay seated for longer and work on a good rythm, also dont forget you might want to just change the rear cassette depending on the current setup as this will give you a wider range of options. You certainly dont need to replace everything, if youre lucky it may be as simple as just changing the inner ring. if your 'unlucky' you might have to adjust the front derailleur. You need an allen key and a screwdriver its a very simple alteration.
     
  3. Peter@vecchios

    [email protected] New Member

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    'large'-ness is subjective. Iy will be easier to climb particularly if you are at you max when climbing in the 42 and boggest cog. It's a bolt on, plug and play procedure. buy a 39t, chainring diameter 130mm, any ring, put on and ride.
     
  4. Guaps

    Guaps New Member

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    I second the rear cassette idea. It's not very expensive. I picked one up last year for an old 7 speed for around $35. Not a nice one, but it was good enough for what I was trying to do. It gives you a lot more flexibility for how you want to gear...
     
  5. Yojimbo_

    Yojimbo_ Well-Known Member

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    I think I have a 53/39 on the front, and an 11 (or is it 12) to 25 on the back, and with that I can go up just about anything around my home.

    Of course, there are no mountains or even big hills where I live, just rollers and glacial moraines. IIf I had to climb some really big stuff, I'd put a 27 on the back or maybe even a compact to give me lots of options until I figured out what I actually needed.
     
  6. rparedes

    rparedes New Member

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    Look at what gears you currently use, what gears give the most trouble, and what you think you need, then go to a gear calculator on-line and compare the distances. You may be able just to switch the rear cassette or switch to a compact chain-ring. Compare what gears a triple would give you and look if there is standard/compact/cassette gear combination that gets close to the "easy gears" in a triple crank. I don't know if the chain/shifters/frontDR will work with a 50/39. I would ask my LBS
     
  7. alfeng

    alfeng Well-Known Member

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    A 38t 130BCD chainring is another replacement to consider regardless of the cassette/freewheel you decide to use in the rear.

    Some BMX chainrings are dual 110-130BCD, so if you can't find a 38t ROAD chainring, ask for a 38t BMX chainring.
     
  8. meb

    meb New Member

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    53-39 is the most common Ultegra double settup. It won't be any major problem. Obviously an 11 tooth change is smoother than a 14 tooth change, but that's just a minor difference.
     
  9. meb

    meb New Member

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    The chainlength will be controlled by the 53. Therefore 42 vs. 39 will be a nochange on the chain.
     
  10. portlester

    portlester New Member

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    Thanks all for your feedback.

    As well as reading your comments I've been doing lots of reading on gear ratios etc & trying not to get too confused.

    My current setup Shimano Ultegra 600 7spd with 53/42 chainring and a 13-21cassette, so it appears that my options are most likely swapping the 42 chainring with a 39 or putting on a 13-23 cassette.

    Looking at the gear calculators, and assuming I've got it right, I can see advantages in both the possibilities when comparing with my current setup. The 39 chainring maintains the 'nice' spacing in the 52 ring, but could result in more double shifting. While the 13-23 cassette could result in less double shifting, has a good lower range. Are there any other advantages/disadvantages?

    So now its decision time & it may even come down to what the LBS has in stock.

    thanks once again.
     
  11. Hillman 531

    Hillman 531 New Member

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    i had this choice some years ago, also having 42/52 but with 12/21 7 speed. I found the following to be best.

    change the 42t for 39t. leave the large ring alone as it makes no difference for bottom end.

    get a casette with a larger low gear, 23 teeth is ok but for hills try 25 or 27 teeth (i should have got a 25t but pushing 23t isn't too bad if the motor is good.) Also unless you really need it for the flats get rid of the 11 tooth cog. 53/11 is a hell of a tall gear to push.:D 12t or even 13t will do.
     
  12. dhk2

    dhk2 Active Member

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    +1 for Hillman's comments. Don't waste money going from a 21 to a 23 low gear; move to a 13-25 or even 13-27 along with the 39 ring.

    Double shifting shouldn't be a concern. In fact, the bigger jumps from the 52/39 and wider-range cassette will be handy on rolling hills, allowing you to just shift chainrings going up and down while clicking less on the cassette cogs.

    If you climb up steep grades, you'll probably get used to cadences down to 50 rpm anyway, even with your new lower gears. Yesterday I was climbing for about 3 minutes at 4-5 mph, ~ 50 rpm in my wimpy old triple, 30/25. Once the grade kicks up beyond 15%, it's hard to carry low-enough gearing for seated climbing without really compromising what you need the rest of the time for the fast pack.
     
  13. Powerful Pete

    Powerful Pete New Member

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    Yup, a 13-21 is something of a racer's setup... get something more reasonable for your fitness levels. At the very least a 25.

    Once you get a 39 up front you should be able to handle most hills with that kind of combination.

    Just have your bikeshop check if such a change may require a longer arm rear derailleur.
     
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