Ryan_M

My GF bought a used roadbike to give it a try. I wasn't there for the deal but it's a full on older 105 3x8 setup (Guessing 5600 - I need to confirm), it looked like a good deal. Anyway the only non 105 part is a Truvative crank that seems to be a PITA. When she got it she said the guy seemed like he knew what he was doing, I put the bike on the stand and went through it all and it was well tuned. I didn't feel the need to adjust a single screw.

She doesn't even have 100km on it yet but the front shifting has been a bit a of a pain. Today we only did 37km and it dropped the chain twice on the low side - I checked the low limit screw and if I tighten it up anymore the chain will rub on small chainring/large cog, so I'm not sure I can do anything there. The chain also jammed in between two chain rings during the ride, that's a new one for me. Any suggestions on what I should look for?.... besides a new crank

delbiker1 

It sounds like an adjustment problem with the derailleur. 5600 is 10 speed, but I am not sure which 105 is 8. I have a Truvativ Elita crank set that has been really good for 16 years and at least 20,000 miles. You can watch videos on Youtube, Parktool.com, etc. that show front derailleur set up. There is more to it than just the cable tension. Was the chain on the small chain ring when you set the tension on the cable and then tightened the clamp? That is the correct starting position. Are the rings oriented on the crank set properly?

fishboat

I run a Truvativ Rouleur (3x9) crankset on one of my often-used bikes. Ultegra shifters and front derailleur. Thousands of miles on that bike and I haven't had any issues.

I'd confirm what derailleur you're actually working with & barring any red flags there, pull up Park Tool's video on setting up the FD and start from scratch with the setup.

edit: I should mention, my crank has to be in the 15-20ish year old category And I assume you're running a proper chain..

Kapusta

The fact that the chain dropped between the rings makes me wonder if something is up with that.

Is it possible that the chain is for a higher number of speeds then the rings are designed for? As you go from 8-9-10-11-12, the chain gets narrower, and the rings change slightly to accommodate. Being 1 speed off works fine, even two usually works fine. But at some point the chain hets too narrow and can slip between the rings.

Also, the FD shape changes slightly as the chain narrows as you increase the speeds. Again there is a bit of leeway where things still work, but only up to a point.

There should be a model number etched into the chain. Find out what it is to rule out the above possibility.

Crankycrank

Agree with the above posters. In addition to checking the chain size and starting from scratch on the derailleur setup you can check to see if any chainring spacers/washers have been installed between your chainrings which would also cause the chain to get caught between the rings. Also, if the cranks are not original it could have a poor chainline from a wrong length BB axle.

Iride01 

TruVativ is a low cost crank. That's why you see them on lower tier bikes that don't have a full Shimano, SRAM or Campagnolo group on them.

However it's very doubtful the crank is any of your issue. It's likely a DR adjusted wrong, worn out cogs or chain, too long a chain or the operator stops pedaling briefly before the shift on the front is completed or even pedals backwards before the shift is completed.

Though if a previous owner put stuff on that just isn't correct for that bike then anything is a guess.

jimc101

? it's a sub-brand of SRAM, and are mid-high end components,

icemilkcoffee 

If the chain got jammed between chain rings, then either the chain is the wrong type or the crankset is wrong.
First things first- you need to note down exactly what components are on there. Can you find a stock photo or spec sheet of the same bike? Try to change everything back to the stock configuration first.

Iride01 

Well in an effort to shorten the words used, I probably misconstrued and maligned a product you feel good about. I have no feeling one way or another for TruVativ.

However the bicycle manufacturers usually keep all of the same groupset together on higher tier bikes of the same model save for maybe wheels. As you move down the same model line to less expensive models you start seeing different brands of cranks, brakes, cassettes and sometimes other weird combinations.

While many times the substituted component is of roughly comparable quality for the tier group the bike is aimed at, the crank, TruVativ, was almost certainly obtained by the bike manufacturer at a lower cost than a Shimano crank appropriate for that tier would have been.

Though there is also the possibility that a previous owner put the crank on the bike.

Kapusta

Did Truvativ even exist when 105 was 8 speed?

Truvativ had higher level stuff back in the 2000s. At least for MTB they did. I think that changed as SRAM reordered their product lines / brands.

Bill Kapaun

I would suspect the chain is too narrow for that crank.
Are there any markings on the chain to denote width?

I wouldn't really expect a 9 speed chain to give problems on an 8 speed crank, but maybe a 10 speed chain would?
Proper spacers between chain rings? Maybe the seller bodged a crank together that seemed OK around the block, but doesn't always shift reliably long term.
Proper FDER "speeds"?

Kapusta

Until the OP response clarifying what chain, crank, and rings he has, there is not much more to do here.

i suspect that crankset may not be what came stock on the bike.