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-   -   Compact Double - Grip Shift Triple Comparison (https://www.bikeforums.net/road-cycling/410635-compact-double-grip-shift-triple-comparison.html)

samersereau 04-23-08 10:24 AM

Compact Double - Grip Shift Triple Comparison
 
I have decided to purchase a Specialized Roubaix Elite, but I need to figure out if I need compact double or triple...

The only comparison I have is what I currently ride. A 2002 Trek 7500 Hybrid with Grip Shifts and a triple.

I live in an area of rolling hills, you can view the elevations of some of my rides at the following site...

http://www.mapmyride.com/search?lstR...tchung&x=0&y=0

On the most difficult hill I an encounter I find myself using 1-4 (Grift Shift Terminology). What would be the comparable gear for a compact double?? Is there a simple explanation as to this gear=that gear?

I am still a noob so I don't quite understand the numbers thing in regards to gears and such. All I know is that the Roubaix compact has a "11-28" as its smallest gear.

FYI I am a clyde weighing in at 260lbs if thats a major factor.

What advise do you guys have as to compact vs. triple?

Added Question. Would it be easy to convert the compact double to a triple?? The components are 10 speed 105s by the way.

Thanks in advance.

chipcom 04-23-08 11:04 AM

Get the triple.

ridethecliche 04-23-08 01:32 PM

A compact with an 11-28 should be dandy. One of your hill rides has 1400 ft of elevation gain in 44 miles. That's not that much.

Take the bike for a test ride and see what happens!

stapfam 04-23-08 01:53 PM

I know a lot here use compacts- myself included-and I do live in a hilly area- but if you are still new to riding you have some fitness to find- and some weight to lose. On top of that- you are used to a triple. For confidence- I would go triple. It is very easy not to use the low gears if you have them- But a different matter if you need them and don't have them.

Porter20 04-23-08 02:18 PM

If you are spending that amount on money on a bicycle, it tells me that you are planning on taking this new endeavor pretty seriously. Since you are taking this seriously, I would suggest getting the compact. It will be a little different but you will get use to it quickly. I looked at some of the hills you have to ride & I don't think you HAVE to get a triple & with any kind of getting small training; you will have no problem with those hills with a compact.

BarracksSi 04-23-08 04:51 PM

As of post #5, the vote count is exactly even. Hmm... ;)

I'd add one thing to check -- poke around the gear range calculator at the late Sheldon Brown's site:

http://sheldonbrown.com/gears/

Put in the gearing of your hybrid, then do it again with the proposed gearing of the Roubaix.

The Roubaix's 34-28 combo (small ring in front, big cog in back) is quite short, and nearly in the "stump puller" category. With that calculator (I often use Gain Ratios), check your Trek's "1-4" gear combo and see how different its ratio is from what the 34-28 can give you.

BarracksSi 04-23-08 05:08 PM

Adding on --

Here's a page about the 7500, which includes the chainring sizes and the range of the rear cassette:
http://www.bikepedia.com/QuickBike/B...7500&Type=bike

The 1-4 that you mention is likely to be a 28-21 or 28-18 combo. The ratios for those combinations are 2.7 and 3.1, respectively.

The lowest gear on the Roubaix, the 34-28 combo, gives you a ratio of 2.5.

You'll actually have a lower gear on the Roubaix than you've been using on your Trek. It's at the bottom of its total range, but if you never need the bottom three gears on the Trek anyway, you won't miss them.


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