eric73

Just needing some technical advise... I read earlier posts on the same topic but could not gain any definite answer to my questions. I just purchased a Cannondale Carbon Synapse with shimano 105 group and a triple crank (came that way). I purchased a carbon SI compact crank set with oversized bottom bracket and am making the change to 50/36 tooth front and 11/23 rear (suits my gearing needs without any losses). Can I use my 2008 Shimano 105 triple components or not? Rear derailleur cage is long, front states triple in writing on the cage, and I understand Shimano shifter/brake levers work for either double or trip. Need a definite answer as I'm going to make the crankset change shortly and need to know what I will need... And if they will work what are the short falls if any? And yes, the whole grouppo will be changed out eventually from the 105 stuff, but I'm trying to spend less now while getting more...

Thanks in advance for your suggestions.

Other upgrades to date (only had it since October) - Spinergy Full Carbon Clinchers 700c (love em), negative g brakeset (love em), soon to have aero bars - it's basically going to be a triathlon bike.

Retro Grouch 

That's a conversion that I've never done myself but I'm 95% certain that all of the components you have will work together.

DieselDan

You should. I use a Shimano 105 (5603) front derailer with a touring (compact) triple 30/40/50.

Al1943

The old front derailleur will be less than ideal but should work OK.
The 105 shifters are double/triple compatible but many Shimano shifters are not.

Al

nitropowered

The only issue you are going to run into is if your Synapse has the SI bottom bracket shell. Cannondale made SI frames with the BB30 shell, and standard frames with a standard 68mm shell. I think all synapses came with BB30 shells and had an adapter in it if it came with a non-SI crank. IIRC, cannondale doesn't recommend removing the BB adapter on Synapse's. Its stated in your Synapse supplement booklet

https://www.cannondale.com/asset/iu_f...uctions_en.pdf

eric73

I'm aware of the manual's comments on removing the bottom bracket adapter for Shimano and other cranksets (don't do it). I actually spoke to my LBS about this, who then called their Cannondale rep, who in fact stated the adapter can be removed... Go figure! So, I don't know. I already have the SI crankset, but also have a Stronglight Pulsion setup on hand if needed.

Aside from this MINOR issue (not really so minor), it appears as if the 105 shifters will work. And, that perhaps I should change out the front derailleur. Any one on keeping the rear derailleur. I will eventually upgrade, but if these work, why change em. 105 shifts just fine, if you ask me... But, I guess I'm the one asking questions here!!!

Thanks for all your insights...

nitropowered

Your triple derailleurs will work, just not optimally. I would first get a double rear derailleur (since you do most of the shifting back there) then get a double front.

eric73

Here's another place of confusion for me. There are long cage, medium, and short cage derailleurs. The assumption I would make is that short and medium cages are for double (depending on front gearing) and that long cage is for triple (due to the larger variation in front gears)? Am I correct here? The second assumption is that I would then typically need a medium cage rear derailleur for a compact setup? And now FSA makes a compact specific front derailleur, anyone have this and does it make any real difference? Again I am going to a 50/36 so only a 14 tooth jump...

Eric

nitropowered

Short cage rear is what you need. Most people use a standard double front derailleur for compact.