jpearl

The Good News:
I finally bought a workstand, and I'm starting to hark back to the days of 15 years ago when I was a high schooler working at bike shops to pay for my addiction. All of the tools were supplied and replacement parts came at cost. Now that I've got my own workstand, I can hoist my bike off the ground, and start saving some bucks over the long run and have fun relearning how to service my own bikes.

The Bad New:
When I hoisted my bike off the ground, I was better able to see what is wrong with my bike. Basically, I have a Cannondale Cyclocross 05 (no discs), and I ride it like a CX bike, so it takes a beating. The derailleurs are 105, and the shifters are Tiagra. The gears shift fine over the smaller 5 cassette cogs on the rear, but then the chain doesn't want to find its way onto the biggest four cassettes after that.

So What's Wrong:
Is there an adjustment I'm missing on the rear derailleur, or is it just these crappy Tiagra shifters that I'll need to toss and pony up like $300+ for new 105 shifters?

cs1

If the Tiagra brifters are shifting fine through the first 5 gears, they aren't bad. You said you ride the bike hard. Did you clean the chain and cassette? Did you check the chain for stretch? I would disassemble and thoroughly clean the bike first. Then, adjust everything. Make sure your cables and chain are lubed. Good luck

Tim

TallRider

It is possible that you've got some gunk built up in the brifter rachet mechanism that could inhibit shifting into one range of gears. I'd rule out other things first (as cs1 says you should do) and while you've got the derailler cable disconnected, see if the brifter clicks through all 8 or 9 gears. If it does, then you're fine. If it doesn't, then maybe the problem is with the brifter. You can flush it out with WD-40 or something. Or alternately, you can take the rubber hoods off and soak in solvent if it's really gummed up in side. Rinse it out, let it dry, lube the inside rachet mechanism, put the rubber hoods back on and get back to riding.

barba

When was the last time you changed your cables and housings? I agree with timcupery; shift through the range with the cable disconnected. That should let you know if the shifter is working.

tellyho

When in doubt, hose out the brifters with WD40. I hear it works well, but haven't had to do it yet to mine.

NoRacer

Grab the cable where it runs along the downtube and pull it, by hand, putting pressure on the shifter. Downshift all of the way until you can see the cable end or know that you've reached the shifters limit. If it's already at it's limit, go to the next step.


Now, grab the cable where it runs along the downtube and pull it a little at a time, as you spin the crank, to see if the RD will shift into the largest cogs. If it does, then you've probably already noticed that you have too much slack in the cable. Spin the barrel cable adjust to reclaim cable length there, then tighten up the cable at the RD clamping bolt. Tune the RD using the barrel adjust.

If you grabbed the cable and spun the crank, but the RD will not shift into the biggest cogs, then you have a "L" (Low) limit screw set too tight. You need to adjust it so that it places the RD's guide pulley in line with the biggest cog when the most tension is on the cable.

If all else fails, go here:

https://www.parktool.com/repair/