Road Bike Shifter Issue

I’m having an issue with the right hand (rear) shifter on my 2002 Trek road bike. It’s a Tiagra dual brake/shifter. The release shifter (towards smaller cogs/higher gears) works OK. The shifter that pulls cable (towards bigger cogs/lower gears) seems like it doesn’t work for about 20 shifts, then works for 3 or 4 shifts, and then doesn’t work for another 20 shifts.

I tried replacing the cable (check ur cables), but that didn’t solve the issue. I’ve been planning to replace the shifter. This weekend, I thought I would try something - pull the brake lever just slightly and try shifting. It seems to work - shifts every time.

Here’s my question - can I adjust the reach on these shifters to pull the brake lever closer to the bar to see if that will make it shift consistently? I find the reach to the brake lever a bit long for my hands anyway. What does the screw on the front of the shifter do?

Sometimes those shifters will just get gummed up and the ratchet mechanisms won’t engage reliably. A good cleaning and re-lubricating makes a huge difference. If you even just have an aerosol lubricant, you can spray into the shifter without your cable installed and shift it through the full range a bunch of times, it should help clean things out so they can move freely again.


That’s worth a try. I had figured that whatever gears are inside were broken or worn down - it surprised me that the shifting actually works when the brakes are squeezed a little, which makes me rethink that theory. After doing a little research, I’m suspecting the reach for these shifters was adjusted by adding plastic shims. Not sure if there are shims still available for shifters of this vintage.

Did you replace inners and outers when you did the cables? Maybe the cable tension changes when the brakes are on.

Been so long since I owned brifters I can’t get my head around how they work…

That’s a good question. I don’t remember now. I think I did replace both the cable and housing.

I did try adjusting cable tension with the brakes in resting position, and it didn’t help. I can see cable tension changing when the brakes are on, but I don’t know that for sure - I don’t know much about road brakes/shifters.

Clean with a aerosol degreser like speedclean brake cleaner, click it like 50times. Clean with a rag and let dry for an hour. Then drench it in a lite thin oil like PL100…clean and click a ton more. If that doesn’t work it’s warn out and done.


Also sometimes the metal wires in the shifter housing pulls through the end cap and pulls into the shifter. If you’re comfortable with it disconnect your cable and check your end cap…but this typically effect both shifters.