wjclint

Since college I have always had a mountain/leisure bike but ride very little. I have never taken a bike into a shop for maintenance and have always done tune ups, wheel truing, etc., myself. My wife got into "spinnning" so we decided to try the jump to road biking. I got a mag-trainer for home and put the mountain bike on it (with a road tire to quiet it down a bit) and will eventually get a road bike. The mountain bike works fine on the trainer - all the gears change just like I am on the road or trail with it.

We bought an entry level road bike for my wife (Fuji CCR2). The Shifters/Brakes are Shimano 105, Front Derailleur is 105, Back Derailleur is Ultegra, Front Crankset is FSA Gossamer - Compact. The back gears shift smooth, quiet, and accurate on the trainer and seems to do the same on the road (it's cold so it hasn't been ridden much on the road - just around the block).

On the front, shifting from the big sprocket to the small sprocket works fine.

The problem comes when shifting from the small sprocket to the large one on the front. Half the time you have to make two attempts - the derailleur just rubs up against the chain and doesn't push it up. Half the time when it does shift it throws the chain off the outside. We have taken it back to the LBS twice to adjust the front derailleur. Things like adjusting how fast you are pedaling seem to help; the squence of shift, let up on the pedals just a little, then pedal harder as the chain comes up, seems to make it more likely to have a successful shift. I have already tried adjusting the front derailleur screw and it seems like the most minor turn of the screw, quarter turn or less, makes a big difference, but doesn't make it work consistently.

With my $100 mountain bike it doesn't matter what gear, what speed, or how hard I am pedaling, it just shifts up and down.

Is this normal? Would an FSA Compact FD be better to go with the FSA crankset (they are on ebay for $15 and weigh close to the same as the 105)? Will it operate better on the road than on the trainer? Am I just expecting to much for it to shift with 100% accuracy and ease?

clutchy

i started getting that a little with my compact crank when i switched... i'm pretty sure i just haven't taken the time to adjust it properly.

I have noticed that it really depends which gear you're in in the back when you shift in the front.

the lower down the easier, but if you're really far down it sometimes tosses it over the other side...


I'm not sure i can help you other than that. Check out your stops on both sides and adjust from there.

Zeriman

I had the same problem with my compact FSA Gassamer crank. It was like the pins on the chain rings where not picking up the chain. After suffering with it for two years I swapped it out for a Campy crank and everything works fine now. Maybe you would have better success with a different crank.

Mekrob

Maybe not even a different crank.. a new big chainring would likely fix it just fine. Much cheaper, too.

That said I had exactly the same problem when I built my road bike (DA 7800 Grouppo w/ FSA omega crank).. Either it was rubbing the inside of the big ring or it would overshift and drop the chain to the outside. Hopefully the LBS did this for you, but I had to start from scratch and go through shimano's install instructions from step 1. Took me a couple tries getting the FD dialed in juuuuust perfect. FD's are very finicky when it comes to height and angular adjustments, I've found.

wjclint

Thanks to everyone for responding so quick. Can you mix and match chainrings and cranksets? As long as it has the 5 bolt pattern can I put a Shimano chainring on the front of the FSA crankset? If so that does sound like the cheapest "try to fix it" option.

Mekrob

As long as the BCD and number of bolts match up, you'll be fine. Compact cranks are 110mm bolt circle diameter, "standard" cranks are 130mm. I've got two FSA cranks and they work fine, but I've heard the Shimano rings are the bee's knees

Best of luck

wjclint

Thanks. I'll give this a try to see if it fixes the issue.

wjclint

Just wanted to close this thread out with a solution instead of leaving it hanging.

Following the recommendations above I replaced the FSA 50t, 110mm chain ring with a lightly used SRAM Powerglide 50t, 110 chain ring that my LBS had. Shifting up to the bigger chain ring is now reliable and consistent.

Problem fixed! Thanks for the advice!

BarracksSi

Just to dig into the opening post --

This bit could be the front shifter's trim function. What happens is, the shifter clicks twice -- one light click, then one heavier click. The heavy click moves the FD far enough to shift to the big ring. The light click, however, moves the FD just enough to avoid chain rub in the small ring-small cog combination.

Check to make sure this still works.

If you knew this already, don't mind me..

JTGraphics

My first thought was also trim, with the 105 shifters a short throw of the lever clicks and FD moves only a little for trim another short click and it will change gears. If you want to shift in one movement it is one long movement, as far as it will go test it out before you start messing with settings first.

wjclint

Before changing the chainring I had tried shifting only after trimming many, many times and it didn't make a difference - the chain still wouldn't go up to the bigger ring most the time. If I adjusted the derailleur out a little bit then the chain would go up and then get thrown off the outside many times. Trimming, or not, didn't seem to make any difference.

I put the bike with the new chainring on the trainer last night and shfited up and down many, many, many times and the new chainring makes all the difference in the world. Looking at the FSA and SRAM chainrings side by side it seems the pins in the ramps (I think that is what they are called) on the SRAM chainring are just a tiny bit longer and the ramp's design is a little different.

bike_boy

Just wondering if the Shimano 105 Front Derailleur was for a standard double chainring as opposed to a compact double? When I moved from a standard Dura-Ace double (53/39) to a SRAM compact crank (50/34), it was throwing chain past large ring much like yours. I found/read that the solution was to lower my FD. (required a change in mounting plate/bracket on seat tube); the other solution would have been to purchase an FD compatable for my compact crankset.

wjclint

The FD is not for the compact crankset. You can see that the arch in the derailleur does not match up to the top chainring so at the far back of the derailleur there is a much bigger gap than at the front. That was my first thought but since I found a cheap chainring, and others on this thread suggested it, I tried the new chainring first which fixed the problem.

BarracksSi

The 105 FD isn't compact- or standard-specific. I didn't change mine when I went from standard to compact, only lowered it accordingly, and it shifts great (Shimano compact in my case).