intern Posted November 1, 2015 Posted November 1, 2015 Hi guys, a question for the fundies here. My wife's Cannondale has an SI compact BB30 carbon crankset with Cannondale branded chainrings. It's running Campag Record 10sp FD and Record chain.The chain frequently goes 'over the top' off the big ring - I cannot for the life of me figure out why. I've tried using a different FD (Ultegra 'triple' and a spare Record one) but exactly the same problem.Does anyone have any suggestions on what I can do? Is the Cannondale branded 50T ring (probably made by FSA) perhaps incompatible with the Campag chain?I'm at the point where I'm going to take those beautifully made carbon cranks and bin them - if it's annoying for me, imagine how irritating it must be for the wife, every time she upshifts she has to do so gingerly so as not to lose the chain!Input appreciated, thanks.
Rocket-Boy Posted November 1, 2015 Posted November 1, 2015 Surely its just a case of setting the limit screws on the FD?There shouldnt be much chance of it coming off if the limits are set correctly.
The_black_stig Posted November 1, 2015 Posted November 1, 2015 The chain frequently goes 'over the top' off the big ring - I cannot for the life of me figure out why. I've tried using a different FD (Ultegra 'triple' and a spare Record one) but exactly the same problem. clearly your front-derailleur is not being setup correctly....1: check the spacing between the outer chain-ring in relations to the FD2: check the outer (or High) limit screw as described by Rocket-boy.3: if step 2 fails, go to youtube and search for "front derailleur setup" videos... edit: "tripple" FD will go against your issues, rather stick with your original 2 speed FD on your problem.
Pah Bear Posted November 1, 2015 Posted November 1, 2015 Can the answer really be that simple? Would have thought the OP would wonder, check out what those screws on top of the FD is for and then made the required adjustments, but then thought 'don't take nothing for granted' just like you guys did.The videos are ultra helpful and should provide the solution. There is very little else it can be ... or is there?
intern Posted November 1, 2015 Author Posted November 1, 2015 Thanks for the comments - but - absolutely most definitely not an issue with limiter screws (I mech my own bikes and have done so for over 20 years; there is very little on a bike I cannot fix, service or set correctly).I tried alternate deraillers to see if the problem was with the FD, but it clearly is not because the same problem persists across all 3 of the FDs I tried. Also whacked a new chain on and checked that the blade is not bent (it isn't...) and the chain bails at random points on the blade, not consistently at one location...
Butterbean Posted November 1, 2015 Posted November 1, 2015 Sorry but I really don't see how a FD that is set properly will overshift te chain. I know some FDs are designed to slightly overshift, then move back to ensure smooth and crisp front shifts, but I can't see it happening. What else could be to blame? Shifting under load? Chain direction incorrect? Chainring on spider correct orientation? If all is correct you should have issues. If you still have issues, it's a setup problem and maybe Yoh should just swallow your pride and take it to your local bike shop and let them advise you/fix the problem. It's probably a lot quicker cheaper than replacing anything again.
Butterbean Posted November 1, 2015 Posted November 1, 2015 oh also check the gap between the derailer and chainrings. Should be as close as possible without contact between the top of the teeth and the bottom edge of the cage plate. Normally a gap of 2mm is max. I would assume this may be off if you've gone from standard to compact chainrings and failed to correct derailer height.
intern Posted November 2, 2015 Author Posted November 2, 2015 Thanks Drago, but as mentioned, I do know how to set up an FD, have done hundreds of them in the past (particularly when I used to work in a bike shop in Maritzburg a long time ago). The chainring is oriented correctly, with the catcher positioned under the crank. The chain gets thrown over the top under load or even when pedaling the bike on the stand. The bike was built with a compact group from the day it was made, so there hasn't been a conversion from standard to compact. The problem is an unusual one, which is why I am asking for any insights outside of the usual solutions to such a problem.The BB, too, is in good nick and properly fitted (a slightly loose BB can cause a chain to bail off the top side).
shaper Posted November 2, 2015 Posted November 2, 2015 Check the facing of the frame bb? If not square the whole bb, crank etc will be skew causing the crank to rotate offline and the chain to go over as the chainring rotates out to in.
BarHugger Posted November 2, 2015 Posted November 2, 2015 Maybe a long shot.....check orientation of RD and if it is straight. Had a similar problem on MTB.......saw that there was rotarional torque on the chain that contributed to it climbing of the big blade (2x10) at the front. Problem was due to bent hanger.....replaced hanger......running smooth again. Does not make sense, but the gremlin seems to have fanished......
David Marshall Posted November 2, 2015 Posted November 2, 2015 I have a similar problem. Not only can I occasionally throw it off the right side but if on the large -large gears I get the chain trying to fall back onto the small ring, not under pressure but when you back off pedalling. Set up is 100%. I have concluded that it is most probably the chain ring. If my ring was new I would try a different brand of chain before changing the ring.
Pulse Posted November 2, 2015 Posted November 2, 2015 Also a long shot... Perhaps the chain has a slight lateral bend in it?
Shebeen Posted November 2, 2015 Posted November 2, 2015 Did it work in south Africa? I've seen things shift for no practical reason at all in new Zealand, like the offside line for instance.
Rocket-Boy Posted November 2, 2015 Posted November 2, 2015 Thanks for the comments - but - absolutely most definitely not an issue with limiter screws (I mech my own bikes and have done so for over 20 years; there is very little on a bike I cannot fix, service or set correctly).I tried alternate deraillers to see if the problem was with the FD, but it clearly is not because the same problem persists across all 3 of the FDs I tried. Also whacked a new chain on and checked that the blade is not bent (it isn't...) and the chain bails at random points on the blade, not consistently at one location...It needed to be asked anyway Ok so if the limit screws are correct then it is very strange. Do you have another crank you cant test with it?Going to be an interesting one to follow.
Pah Bear Posted November 2, 2015 Posted November 2, 2015 When I had my frame built, I asked my LBS to install the press fit shim. They offered to include installation of the bb if I provide it (same price) so I agreed. Next question - should they torque it up or do I first wanna check alignment and talk up myself.Long story but ... could front to rear alignment be a problem? Hope you sort this out and share info. Always felt the FD is the easiest of all to get right and manage. Now I know different. Following.
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