General Discussion Triathlon Talk » 20 speed vs 18... any difference? Rss Feed  
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2009-07-28 1:39 PM

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Subject: 20 speed vs 18... any difference?
I'm riding on an 18 speed tri bike and there were times that I had wished I had two extra gears to get over some tough climbs. Would there have been a difference is the question.

The bike I use is a 2005 Felt S32 mix of Shimano 105 front and rear derailleur, FSA Gossamer cranks, Shimano Dura-Ace 9 speed bar end shifters.

Should I go with a full Dura-Ace setup or would that be financially unwise?

Or... should I get a new bike?

My hill training sessions are fun and hard but it just seems the struggles could be less if I had two extra gears. Am I right? Wrong? Confused? Or do I just live with it?


2009-07-28 1:47 PM
in reply to: #2313123

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Subject: RE: 20 speed vs 18... any difference?
You don't need to go to ten speed you need to get the correct gearing for your courses/ability level.

The S32 came stock with a 12-23 cassette (and 53/39 chainrings) so if you find yourself running out of gearing on a climb, you could go with a 12-25 or 12-27.

Shane
2009-07-28 1:48 PM
in reply to: #2313123

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Subject: RE: 20 speed vs 18... any difference?
that really depends. are willing to drop a load of cash for full DA when you could put that toward other things? and it also depends on the range of your cassette in the rear. you could have a really closely spaced 9 speed cassette, like an 11-23. changing cassttes would make more of a difference than an extra chainring in the cassette. i would say that you find out what the spacing is on the cassette you have now, and look into buying a cassette with more range before you spend a ton on a new bike or full 10 speed DA.
2009-07-28 4:50 PM
in reply to: #2313123

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Subject: RE: 20 speed vs 18... any difference?
As others said you need to know what you have today.

That said I went from a 12-23 10spd to a 13-25 10sdp cassette.  I kept the same range but moved it all up one.  With the 53 ring and 13 cog I can pedal to 34 mph at 105 rpms then tuck and still accelerate coasting on the big hills!  I'm not a monster rider so all this works for me.

If you keep the same lower (say 12) and move the big cog to a 25 or 27 from a 23 you will be increasing the spacing between the big cog gearing, depending on what cogs you use the most of, you will in effect be "losing" a gear.  Today the Tiagra line is the 9spd group and the website doesn't provide the cassette range options.

Perhaps a new bike would be wise   Personally if I were to get a new bike today, I'd look into a compact crank and use a 12-25 10spd cassette.

So in short you have 3 options (other than just changing the cassette range), New bike, 10sdp group (today's 105 to DA line), or get a 105 compact crank up front.


Edited by Donto 2009-07-28 4:53 PM
2009-07-28 5:03 PM
in reply to: #2313123

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Subject: RE: 20 speed vs 18... any difference?
As the others said...It does not matter how many gears you have. I have an old 5 speed set up that has the same gearing as my current 9speed tri bike. Just not as many choices in between!

9 speed is cheaper, still does a great job, and many people say stronger. The chains are a tad wider so some people say that they last longer.

Take it for what it is worth, just stuff that I have read on the internet.
2009-07-28 5:15 PM
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Subject: RE: 20 speed vs 18... any difference?
Another repeat....

Going from a 18 to 20 will add two more gears within the range, but not increase the range or give you "two more" low end gears.

You need to check the rear cassette and go with a bigger range 9 speed.  Like a 12-27.  I have one of those for my hilly climbs and serves me well.

The next option would be a compact crank (if you are running a double) which reduces the small chain ring from 39 to 34 tooth.  That will move your whole "range" of gears down basically a gear.  That means you have one less fast gear, but one more slower gear for climbing.

After THAT, you could go to a triple chain ring which has 30 teeth for a small ring, and that will get you one MORE low end gear.

I have recentlly been doing a lot of study into gearing, and came to the conclusion that a compact crank with an appropriate rear cassette is the best way ride for 99% of riders, IMO.

Edited by Aikidoman 2009-07-28 5:15 PM


2009-07-28 5:24 PM
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Subject: RE: 20 speed vs 18... any difference?
Aikidoman - 2009-07-28 5:15 PM
a compact crank with an appropriate rear cassette is the best way ride for 99% of riders, IMO.


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2009-07-28 5:32 PM
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Subject: RE: 20 speed vs 18... any difference?
As others have said...

1. I'd suggest going to a different cassette with an easier gears than you have as it is the least expensive option. Find out what you have, and go bigger. I think a 12-27 is nice for folks, but it really depends on your strengths as a cyclist and how hilly it is where you are riding.

2. Next option is to switch to compact crank but that will be probably double or more than the cost of the cassette. But again you will see a big difference.

3. Upgrading bike to 10 sp to me is waste of money. New group is expensive and about half the cost of many new bikes and if that is what you want, I'd get a new bike, which is way more cool than option 1 or 2 but probably 30-40x or more the cost of a new cassette.

I have probably 5 different cassettes I use depending the course and terrain I'm riding. Flat I use 11-23, standard around where I live is 12-27 or 11-28. I even have a 11-34 I use on long hilly courses....need a MTB derailuer so not super easy to swap out like a cassette.
2009-07-28 5:37 PM
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Subject: RE: 20 speed vs 18... any difference?
Donto - 2009-07-28 2:50 PM
Today the Tiagra line is the 9spd group and the website doesn't provide the cassette range options.


There are plenty of other options that aren't brand new or Shimano yet still quality 9 speed cassettes.  SRAM, NOS Ultegra/105, Miche, IRD, etc.
2009-07-28 5:52 PM
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Subject: RE: 20 speed vs 18... any difference?
1. ride more

2. change your cassette...and/or get a compact front, if you really need to.

Nothing wrong with the bike you have. DA won't get you anything over 105 10 speed aside from an empty wallet. And If you're using your gearing right, you most likely don't need 10 over 9, anyway. Plus switching out your drivetrain is a PITA, and WAY expensive.

And hills aren't supposed to be easy. ;-)

Edited by mmrocker13 2009-07-28 5:53 PM
2009-07-28 5:55 PM
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Subject: RE: 20 speed vs 18... any difference?
scorpio516 - 2009-07-28 6:37 PM
Donto - 2009-07-28 2:50 PM
Today the Tiagra line is the 9spd group and the website doesn't provide the cassette range options.


There are plenty of other options that aren't brand new or Shimano yet still quality 9 speed cassettes.  SRAM, NOS Ultegra/105, Miche, IRD, etc.

Yes there are, good point, I didn't research any of them. 

Ultegra/105 haven't been 9 spd for awhile now, I guess one may still be able to find a barely used one somewhere.  BTW, my brand new Ultegra 13-25 was almost 50% off via Nashbar on one of there big sales.  I never pay full retail!


2009-07-28 6:00 PM
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Subject: RE: 20 speed vs 18... any difference?
You can find new shimano 9 speed, as well. Pretty much anywhere you buy parts.
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General Discussion Triathlon Talk » 20 speed vs 18... any difference? Rss Feed