I figure a bunch of you toy around with builds and mix and match componentry so you might be able to help me out. Thanks in advance.

Background:
I worked my ass off to get together the money for a build I just finished. It's an 84 trek 760 and it has a mixed drivetrain. The front der is the original suntour superbe, the rd is a veloce, the shifters and cranks are campy centaur (compact crank), and the chain and cassette are shimano 105. I know it's a real crazy mix of components, but I put it all together about 2 weeks ago and it all worked really well. The LBS was amazed that the shimano spacing could be made to work and I was just thrilled that it all worked well enough to ride.

I raced the bike this past weekend and it didn't mis shift and let me down at all. It was a blast to ride and I was glad to be able to leave my cannondale at home since the weather was going to be nasty and I didn't want to end up crashing the bike (it was my first race).

I went out for a 25 mile ride on the bike yesterday and everything was working fine.

The Problem:
The problems started today, I set the bike up on the trainer and was spinning pretty easily. I was in the middle of the cassette and I decided to shift down to the smaller chainring. All of a sudden, there's no tension in the chain anymore. The chain is just gliding on top of the small chainring and it refuses to go onto the small chainring. If I shift up and down a few times from the big ring to the small ring, it'll eventually fall into place, but it was NEVER like this before. It just 'glides' or 'skates' over the small chainring and refuses to drop onto the small chainring...

While trying to do this, the chain not only dropped onto the bb off the small chainring, it also fell off the big ring and scratched the crap outta the finish of my cranks... I understand that I can drop my chain if I'm really badly crosschained and I shift in the front, but I have no idea how to fix this problem.

I'm really distraught about this and I honestly can't figure out what's going on.

Please help me out?

Thanks in advance.

It looks like the chain gets stuck between chainrings if I shift when on the middle cogs of the cassette, I guess this might make sense because of the angle of the chain, but the chain is a 10 speed 105 chain and the cranks are 10 speed also, as campy has been 10 speed forever...

Is a 10 speed campy chain much wider than a shimano one?

For now I guess I'm just going to have to mind my shifting habits and shift in the back before shifting in the front to avoid this happening.

Would it be possible to use a triple FD and lock out the limit screws so I don't throw the chain onto the frame? If I need a new fd, that might be the cheapest way to go about finding a working solution. An older shimano or campy clamp on FD?

Any ideas?

Before you think about more parts, I'd go back through the cable and derailleur settings and make sure the front derailleur travel is limited the right way. Usually overshifting off the chainring is due to the cage moving too far. This problem can be present on the front and rear derailleurs, and on both the inner and outer limits.

Hi there,

Is your chain too long? That's the first thing I thought of.

https://www.parktool.com/repair/readhowto.asp?id=26

That would explain going over the big ring, but not the inability to shift onto the small ring. The limit for the small ring is set to go as much as possible and it still doesn't shift into the small ring all the time. The limit screw is set so the FD can move as much as possible when it's shifting down to the small ring.

I used their method to set up the chain. Big ring, big cog, 1 extra link. Done.

I don't think it's the chain length that's the problem.

Could I lock out the limit screws and possibly use a triple fd to get the little bit of extra movement I might need? The superbe FD might not have the range of motion to shift a 50/34 100% of the time.

Thanks for the input!

Just a thought - did you get your allen keys out to make sure all your chainring bolts are tightened to spec? I'm just wondering if yesterday's ride might have loosened a chainring bolt or two, causing your setup to become slightly off-parallel and incurring shifting problems.

Is your derailleur hanger (on the frame) bent? If you eye your RD from the rear, is the pulley cage lining up more or less parallel with the cassette? Is it skewed toward either the driveside or the non-driveside?

On the FD, you may just have to tweak it a bit, toe in or toe out...

I think this is likely. I had to monkey around with the toe-in and limits to get my 760 to shift properly onto the small ring. I think the modern spindles may be a little longer than what was used in 1984, which could cause what we've both seen.

I suspect the Superbe FD is too wide. Its cage is spaced for a 7 speed chain and chainrings.
There's probably a big enough gap to allow the chain to drop off the rings.
You can try to pinch the cage narrower, and replace the spacer between the plates with something a few millimeters shorter. A nylon lift-off for motherboards come to mind. Or a series of small flat washers.

As for chain length, it can still be too long...as you mentioned it seemed to not have enough tension to force the chain to engage the small chainring.
I'd check to see if the pulley cage has enough pull on the chain while you're in the small cog/small chainring combo. You are running a compact crank.

Well my limit for the FD for the small chainring is as far as it'll go. I'll mess with the toe in, though I tried that and it got to the point where it wouldn't shift up to the bigger chainring, though I could adjust the limit screw here to get that to work.

I'm so bummed about the finish on the crank, it's all marred up now though I guess it could be a lot worse...

I'll get my RD hanger looked at. I think I might have cross threaded the RD when I was putting it in and this could have caused the problems on the back as far as the chain shifting onto the dropouts which are now marred as well...
If I adjust the RD limit screws, it doesn't shift onto the small cog. I'll take it to the lbs to have them look at the RD hanger alignment and chase the threads on the RD, though they'd told me not to worry about it if it was shifting, which it is. I'll look into doing that in a bit though, when I have a little more money to spend on bike stuff.

Thanks for the help everyone. I'll toe in the FD and adjust the limits to see if that helps. I'll do it in the afternoon possibly since I want the time to be able to run to the LBS if I just want to give up haha. I'll let you guys know how it goes.

As an additional question: Would a triple FD work? Could I adjust the limits enough for it not to throw a chain on a double? I could just use that if this doesn't work.

Also, if the RD shifting works, should I still get the threads chased and the RD aligned?

Thanks again.

If the chain gets stuck in the space between the big and small chainring, is that still a tension problem in your opinion?

Thanks.

fyi - when adjusting the toe - a mm can make all the difference - as can the height. On the height, the FD should be able to clear the large ring by no more than 1/4" when you shift to the big ring.

I used a penny to determine the clearance of the fd on the big ring.

I'll play with the toe in today. I'm really hoping that's all it needs...

Is this a 10 spd Centaur crank? I find it odd that the 10-spd chain would fit in between the chainrings.
Maybe a 9 spd spacing?
This is a different matter from the chain skating on top of the chainring. Not enough tension can still cause this as there should be enough tug to cause the teeth to wrap the chain onto the ring.

I don't think the triple FD will solve anything. if your chain can easily fit between the big and little chainring this is a problem. are your shifters and crank set up for the same spacing?

edit: I just saw your signature, put that superbe stuff back on!

I hope this doesn't confuse the issue too much, but my Campy 50/34 setup has a compact-specific front dérailleur, and shifts much better than another bike that has a compact crank but a dérailleur intended for a 53-39 8 speed system.

The superbe was some pretty race specific componentry and as such was limited in what it
could handle. I wonder if the FD just won't handle the drop from 50 to 34, remember the
usual setup back in the day was 42 52 nothing like a 16 tooth difference.
I'd start looking at a Centaur Compact FD.
and yah, I agree with g-Funk put the superbe back on it.
marty

edit looked up superbe capacity and it is either 16T or 18T, so I stand corrected. It should
handle the difference. That said I stand by my statement of either put a centaur compact
or all the superbe back on.

marty

I'd love to put the superbe stuff back on, but I can't do hill rides on a 52/42. That's why I started swapping things in the first place.

I bought the crankset from performance and its a 10 speed setup. I think the chainring bolts might have worked themselves loose. I'll tighten them up and see what that changes.

With all due respect to every one of you awesome C&V'ers, I loved the bike the way it was built, but it doesn't fit my needs for a training/backup race bike with the superbe stuff on it. The 52/42 is a little extreme gearing for hill rides and the spacing doesn't work out well with a 13-28 cassette or the like. I have to admit that I'd love to put the superbe brakes on there because, face it, they'd look a lot better AND be lighter than the centaur brakes. However, they don't work as well as dual pivots and having better brakes is more important to me than having lighter brakes.

How I wish that the campy brakes looked that sweet though

I love the parts and I love the frame, but the superbe parts just weren't what I needed on this build. I can't have downtube shifters and a 52/42 on this bike because I can't handle that gearing. It works fine.

If you like the stuff, buy it, it's for sale

I posted this question here because a bunch of the regulars on this forum do put the newer campy parts on some nice older frames and I thought that the mix and match componentry, old and new, would have some people interested in either seeing what was going on and or helping out, which has been the case.

Thanks for all your help.

Like I said, I'm going to try tightening the chainring bolts and see how that works out. It could decrease the spacing difference if the bolts worked themselves loose. I hope it works!

just giving you a hard time about the superbe stuff, but where do you live where you can't hang with a 42-28? Maybe when you build up your strength with all your racing you can push bigger gears and then go back to the superbe components. I'm an italian bike nut and think that the suntour components were the best, simplest components made. I think your best bet would be to buy a campy 10speed front d and play with that, if the chainring bolts don't work. There's a reason that bikes don't typically come set-up with mismatched parts.

Not directed at you personally (because I think you live somwhere here in the Bay Area), but I really get tired of hearing this. Not everyone lives in Florida or Kansas where freeway overpasses count for climbs - some of us have to deal with protracted, respectable climbs every time we go out. Coupled with the fact that some of us (me, for example ) are about as strong a rider as we're ever gonna be. I'm not going to "get stronger" by mashing a ridiculous gear combo for my environment, but I might well ruin my aging knees. No, thanks.

RTC - you once asked me if the vintage Suntour Superbe stuff would work with the modern Campy 10 speed stuff, and the best I could offer you was "try it and see". Looks like you did, and it doesn't. Mix 'n match doesn't work great with the newer stuff, and you're not getting the full potential of the performance it has to offer when you try it. Go to eBay, get the proper Veloce/Centaur FD for ~$25, and be happy.

If the chain is falling between the rings then the chain is too narrow, the chainring gap is too large, or the FD is too wide for the chain and is allowing sloppy shifts - with poor and unpredictable results.

I live in Santa Rosa. This was a tongue in cheek comment and wasn't meant for everyone it was meant for our compatriot RTC who is actively racing his bike and going on training rides, these training rides are designed to make you a stronger cyclist. Stronger cyclists push bigger gears. I, like you BBM, go on bike rides, not training rides


Go to eBay, get the proper Veloce/Centaur FD for ~$25, and be happy.


well said.

Seems really odd that the chain is dropping between rings (is the inner ring installed backwards?). But I will add my voice to the chorus and say get a compact FD. I had a regular centaur 10 speed double on my bike with the correct FD and when I switched to compact I didn't even mess around I went down to the LBS and bought the century grey compact FD to match. Even still it doesn't shift great. I should actually try tweaking it before the next ride.