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Gear ratio’s?


_Daemon_

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What's everyone's gear ratio's, thinking of buying a new crankset(actually new campy groupset) and trying to figure out if I should go for a compact crank.

 

How would a 50/34 with a 11-23 casette work? Would I have the same top end speed of a normal double but with a 12-25 casette in the back and better climbing gears?

 

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Road: 52 / 42 with 12-23

 

MTB:   Dont have a clue but I have a sop bord for a granny smiley36.gif

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Try this link from FSA for an explaination: http://www.fullspeedahead.com/downloads/compact.pdf

Interactive spreadsheet for comparisons: http://www.fullspeedahead.com/downloads/copy_Rollout%20chart .xls

I must admit I havent read through it myself, but have looked at the comarisions and comments from other people and understand that the 50/11 gear is a bit faster than a 53/12 gear on the flats (for the same cadence), and the 34/23 is a bit easier than a 39/25 gear on the climbs.

The advantages are a slighly lighter drivetrain (smaller chainrings, smaller cassette and a shorter chain) and closer gear ratios. Some people say that a compact (more curved) front mech is required while others say that a properly adjusted from mech is sufficient. Shimano doesnt do anything special, but FSA and Campy have compact front mechs.

Good luck with your desicion and enjoy your new groupset!

splat38933.3538657407
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Splat has it spot on.  50-11 is as near as dammit to 53-12 as you would care to be, and 34-23 is about 39-26.  So you lose nothing but have a wider spread of gear options.  It is true about compacts dropping the chain more often as the jump from 50-34 is much bigger than 53-39.  Despite that I don't see myself ever riding a 53-39 again.

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I've got a 50/34 - 11/23 and the 34/23 was used quite a bit at the top of boulders smileys/smiley9.gif, however I think that for 95% of races, with racing up and down rolling hills  a 50/36 would be better as there is a huge gap between the big and small chainring. If you are a LA wannabee and go up hills spinning like a MTBer in the granny gear then get the 34!

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Can I make the assumption that for me to convert my current crankset (53/39) to a compact will only entail changing the crankset itself, nothing else?

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Ratio = 50 * 27 / 11

 

 39533650
1195.72727130.090988.36364122.7273
1287.75119.2581112.5
1381110.076974.76923103.8462
1475.21429102.214369.4285796.42857
1570.295.464.890
1665.812589.437560.7584.375
1761.9411884.1764757.1764779.41176
1858.579.55475
1955.4210575.3157951.1578971.05263
2052.6571.5548.667.5
2150.1428668.1428646.2857164.28571
2247.8636465.0454544.1818261.36364
2345.7826162.2173942.2608758.69565
2443.87559.62540.556.25
2542.1257.2438.8854
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Assuming the the crankset you choose uses the same bottom bracket, you should be A for AWAY! (I dont think that there are any Q factor issues).

You would have to drop your front mech slightly and possibly shorten your chain a bit.

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Splat, I got a FSA Gossamer crankset with external bearings and a 31.8mm clamp on front der.  Would I only have to buy the crankset?

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Take one link out the chain, drop the front derailleur about 5mm and you are done. No need for a compact derailleur, a friend has one and I don't, neither of us drops the chain very often (not more than I did before anyway).

I use a 25-12 for training and a 21-11 for racing with a 50/34 up front, its the best thing since sliced bread.

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I have one of those "can't drop your chain from the small ring" type thingys on my bike!  Thanks Sir Fred, now to get a LBS that stock them and pricing in cold JHB!

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ewep: if the compact crank you buy uses the same BB as your current one, you are ready to go. Your LBS should be able to sort you out.

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Does anyone in Jhb know of a LBS that stocks FSA?  I've phone Cyclelab and Westdene cycles and no one has a crankset available.

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Try Slipstream Cycles, I thought I saw a FSA in the cabinet there the other day - 011 463 7226

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