Compact vs. Triple Crank?

[Phil Daigneau]

I just traded up my 2008 Trek 1.5 Triple for a 2009 Trek 2.1 Compact.  What does other use / prefer and why?  Should I pushed to have a triple?

Need some advice....

[Judy Frankel]

both might give you the same gear inches for climbing.  You need to have them figure this out for you.  There is a formula they can use to do it.

You also might compare the overall weight of both.

I have used a mountain bike derailleur and a larger big cog in the back to give me more climbing gears.   Compact cranks are a newer way to do the same thing as this or a triple.   I'll be getting a compact on my new bike.

I'd rather have the lighter compact than any of the other alternatives.

[Phil Daigneau]

Judy,

Thanks for the reply, i'm still trying to figure this message board out because it seems that not to many people respond.  Being new I'm hoping to utilize this board to learn from others and hope other will get more involved.

[JohnH]

 As an old grump myself, my best advice is to forget all of the hype and hoopla. Buy a single speed bike and enjoy the ride. You'll love it!!

[raleigh]

It really is a matter of personal preference and needs.  Lots of loaded climbing?  Probably a triple.  If you are an average to strong rider you should be fine with a compact.  Why not try the compact since you already have it on the bike and then decide from there?  I went from a triple to a compact double and wouldn't go back, I like the simplicity of  2 chainrings.  The triple will probably give you a bit lower low gears and a bit higher high gears but the compact is a good compromise between a triple and a standard double.  Here is an excellent online gear calculator to figure out gear ratio etc...  http://www.sheldonbrown.com/gears/

[Phil Daigneau]

Raleigh,
That was the advice that Andy at the Trek store said.  He rides with a compact and prefers it over the triple.  I originally had purchased the Alpha 1.5 but didn't like the shifting on it, they allowed me to trade it up for the 2.1 and Andy did an outstanding job of getting me set up on the new bike.  Can't say enough for the Trek store they earn my trust and business.  Once I get my miles up to feel confident that I can keep up with you group I'll be out.

Thanks for the response.

[karlos]

Besides the weight savings, for basic road riding  the 34/50 compact with the standard 10 speed 11-23 (11-17, 19, 21, 23) gives a remarkably evenly spaced set of non-overlapping gear ratios (click on Raleigh's link for the calculation), so you really get close to 20 unique usable gears, although you should avoid the cross-over extremes. I really like the smooth shifting, However, in my wimpy, lazy, old age, I keep the 12-27 cassette on there for senior moments in Fallbrook. Also, you might be surprised to find that the 50/11 is actually a 3% higher gear than the big 53/12 (do the math), so you really shouldn't spin out - my philosophy is: if you're going over 35, it must be downhill anyway so stop pedaling and enjoy 

[Wayno Caldwell]

This is a subject close to my heart, or actually my bike, which by the way isn't getting much use right now cause I'm scheduled for my third back surgery and hopefully will be able to ride again early next year.

But, I just wanted to say that after riding and racing from 1994 to 1999, I never had an issue with the traditional 39/53 and 8 gears in the back. After my encounter of the wrong kind with a truck in March of 1999, I was off the bike until August of 2002. And in coming back after three and half years off the bike, I built a Merlin Ti with Dura Ace Standard 39/53 9 speed, and after a couple of Double Centurys, I decided to upgrade to the Dura Ace Triple crankset. Wow, I loved it. Then I sold the Merlin and purchased the Specialized Roubaix Pro in 2005, which came with the compact crankset. But after riding 8 doubles with the Triple on the Merlin, I found the compact to be just enough different, that I switched back to a D/A Triple 10 speed. It was  just like I remember it and it's funny, but all I can say is that you can get by with anything you want to, or try different things and see for yourself.

And as a side note, the new D/A Triple 10 speed only comes with a 52 . . . But the 30 sure comes in handy :-)

[Lisa Ruby]

Hi,

I've been thinking about this issue for a while too. I want to do something to add more climbing gears to my bike. My situation is that I have 650C wheels, so I have been skeptical that a Compact Double would be a good choice for me.

It's been so long since I built up my current bike that I have forgotten what my gearing is, but I think I currently have 53/42 chainrings and a 9-speed 12-25 cassette. This gearing mostly works for me, but on steeper climbs I'd like a few more gears. I recently bought new wheels and I don't think they'll take a 10-speed cassette so I'll probably want to stick with 9-speed.

Anyone have thoughts on putting a Compact Double vs. a Triple on this bike with its 650C wheels?

Lisa

[Judy Frankel]

Lisa.. it doesn't matter whether it is a double or a triple.  You need to calculate the gear inches for each one.  They can be the same depending on what gearing you have.

Another option is to put a XTR mountain bike deraillur on the back with a 31 cog.  I have this on my bike with 650 wheels.  and it will  be less expensive to upgrade your current 9 speed doing this instead of getting either a compact crank or a triple.  It will have the same outcome.

On my new bike, I am getting a compact crank with a 28 cog in the back.  I still probably won't have as much gearing on this bike with 700C wheels as I would have if I had 650's on my new bike and the same gearing.

Have someone do the calculations for you or teach you how to do it.

Judy

[Lou]

Lisa,
The 9 and 10 speed casettes will work on your new wheels. You'll have to upgrade your shifters though.
On the calculations for your gearing, it's called "Gear inches". Divide the number of teeth on the rear cog into the number of teeth on the front cog and multipy by the wheel circumference. You end up with a 2X9 or 2X10 table. As Karl said, you can see the overlap in gearing. So for every complete crank revolution, the rear wheel turns a certain number of times. And one rear wheel revolution is equal to so many inches of wheel travel.
In my "race days" I had created a spreadsheet that calculated a series of gear combinations for a gear inch comparison. I thought it would help me select my gears for race day based on the terrain of the course. I can probably update it and send to you if you like. Just let me know what your choices are....
I found it!! Here is an updated example of a 52X39 front crank and a 12 X27 10 speed rear cassette. You can see the overlap Karl mentioned. Also, wheel circumference is a relative issue. I think I used a general 700X23C wheel for those calcs. Gear inches will be smaller with a 650 wheel. The the comparison is the same.

52X39 12-27 cassette                     
52 X 27   160.33      39 X 27   120.25
52 X 24   180.38      39 X 24   135.28
52 X 21   206.14      39 X 21   154.61
52 X 19   227.84      39 X 19   170.88
52 X 17   254.65      39 X 17   190.99
52 X 16   270.56      39 X 16   202.92
52 X 15   288.60       39 X 15   216.45
52 X 14   309.21       39 X 14   231.91
52 X 13   333.00       39 X 13   249.75
52 X 12   360.75       39 X 12   270.56

But just to keep things simple, I would suggest a compact double (50X34) for your application. You'll have a more enjoyable time climbing and sacrifice a small amount on the high speed end. Adjustment is a bit easier too.

Lou...
                     

[Judy Frankel]

You can also calculate the gear inches with a 31 cog on the back of your bike.

This is what you'd get by adding an xtr derailleur.  It is the cheapest option because all you'd need to change out is the back deraillur and cog set and you'd get everything you need.

Check out the comparison in gear inches on your three options and the price to switch your bike to each.  I think adding the XTR will be your least espensive option.


Judy

[Lisa Ruby]

Thanks Lou and Judy. The information is very helpful and much appreciated. Lou, I'd be very much interested in a copy of your spreadsheet. I  have to sit down and take the time to do all of the calculations and compare the various options. With the 650C wheels I think I'd probably not be happy with a 50 large tooth chain ring as I think I'd miss my top gear, but I need to do the calculations to see what would actually happen. Right now my big chain ring is a 53. I do use my top gear. That's one of the reasons I've seriously considered a triple over the compact double. When I had bikes with 700C wheels I ran a 52/39 in the front and had to go to the 53/42 on the 650C setup to get the same gearing.

Lisa

[Lou]

Lisa. You have mail.
Lou...

[Judy Frankel]

Lisa.. you would not miss the "top" gear in the front.. which is for descending anyway.. because you would have gearing in the back to make up for it.

But, to accomplish what you want to accomplish. which is too have easier gearing on climbs.  you may just need a Bigger COG in the back. 

People have added a bigger cog onto the back than a 25 even with the existing set up you have.. Although, most bike techs will say that you can't have a 27 cog or a 28 on your existing set up people do it without a problem.   The bigger the cog in the back the better for climbing. The smaller the crank in the front the better for climbing.  The more gears.. the smaller the jump is between each gear change. I think you can even add a 31 cog without a problem although probably techs will tell you you can't.


If you want a really big cog in the back without having to change out your whole bike you can just change out the deraillur to one that will accomodate the bigger cog.  The Shimano XTR will do that so add this option to your calculations when you are deciding. There are 3 things that you can do.  Add a bigger cog to the back which might require a new XTR derailur, a compact, or a triple.   A triple will probably cost the most.

Judy

Judy