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Discussion Starter · #1 ·
Need some advice. I have a Trek Madone 5.9 and it came with the Shimano 10 speed group. I need a little more help for the hilly area in which I live and am going to go to a Shimano Compact 50-34 crankset.

I have the compact crankset in hand but need to know what else I need to make the swap. Different front deraileur? Bracket channel to lower Deraileur? BB bearing or other related parts? Other things I don't know about?

I have gotten different comments from the two LBS's I asked so I thought I'd get the straight scoop here. Many thanks.
 

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Discussion Starter · #3 ·
Downward Adjustment

I have the 700. Are you saying there is enough room on the deraileur bracket to move it low enough for the smaller chainrings? This is where the LBS guys went different directions.

Glad to know the current deraileur and bearings, etc are what I need.
 

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I recently replaced a 53/39 Ultegra crank with the R 700 compact on a 58cm Madone 5.2. I didn't touch the Ultegra front derailleur at all, which left the outside cage plate a whopping 8.0 mm above the large compact chainwheel. To my surprise, it shifted the chain across the compact without a problem.

Moving the front derailleur as far down as it would go put it about 3.0 mm above the chainwheel and gave me slightly quicker shifting. IMO, the R 700 compact is designed to work well with front derailleurs much higher than the standard 1.0 mm gap recommendation.

I did have to take two links out of the chain. And I haven't thought this through yet, but I keep thinking that frame size could have a bearing on how well the nominally too-high front derailleur shifts the chain across the compact. It's possible that my experience with the 58 cm Madone may not carry across to other frame sizes.
 

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Forgot to say

that I removed 2 links because I didn't change the cassette on that bike, and that the chain was a bit long to begin with. Point is: look at the chain after the compact installation. You might not have to do anything.
 

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I run a Shimano compact with regular Ultegra double 10S - works great.

If you've got the cranks in their usual packaging, the fitting instructions should be in the packaging someplace. Go to the Shimano website, download the fitting instructions for the front derailleur. Follow them to the letter, and in order - if you do that, you will do just fine.

Not sure as to how your front der will fare as to vertical adjustment - mine's the clamp around the ST sort, so it matched up to the rings easily. Would suggest that if your fr der won't drop down to the ideal position, first try it as low as it will go - if it works, there's no problem to bother with!

Shouldn't have to touch the adjustments on your rear derailleur, though you may have to take a couple of links out of your chain - I'd follow the suggestion above and do that last, if needed. The rear der. has to cope with a larger variation between large ring / large cog and small / small than with 39/53. However, it's unlikely you'll be able to use 34/smallest cog combo - the chain will likely hit the big ring.

On my rig, with very short chainstays, I effectively 'lost' the smallest two cogs on the small ring due to the chain hitting the big ring. So I could take the chain sagging on the small / small case, as its not usuable anyway.

Hope that helps

Dereck
 

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You don't specify your FD as Ultegra or Dura Ace (or 105). Wim specifically states Ultegra. Dura Ace has been known to be fussier than the others about positioning.

You can gain a mm or so of down adjust with careful application of a rat-tail file to the mounting tang...
 

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I changed my Felt F65 to a Compact. My shop had to remove three or four links from my chain. Works great, shifts great. I did have to buy a new bottom bracket, because my Felt was a 2005 with the internal bottom bracket.
 
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