Downtube shifting

[Acoolusername]

So this is my first road bike and it has shifters on the down tube. It has indexing clicking on the right and the left is just smooth for two rings. I can’t seem to get it quite right but a few gears without it grinding while riding. What am I doing wrong? I have the left set to the small gear and when I switch between the clicks on the right they grind while riding. I don’t believe it’s a derailer issue because I just got the bike from a bike shop that took it apart and redid stuff before they sold it.


black lightning 1987 replies:

Does it grind going both up and down? If it shifts better in one direction than the other it's usually an adjustment. You may need more or less initial cable tension, which can usually be adjusted with the barrel adjuster on the derailleur. Are your shifter and rear derailleur both Alpha 3000? That model needs to have both parts matching. Other SunTour models used a different cable pull ratio.

 

[black lightning 1987]

See above. Updated my adblock, and able to post now.

 

[Acoolusername]

I was looking into it and also found out that if the left one is out of tension a little then that can make the noise. Unfortunately I can’t ride until tom after work but I will def play around with the left/front shifter. I thought that if it’s all the way up that it would be on the cog. Or all the way down but since it is tension I guess it could be somewhere lower or higher am I correct? So if I just have it pushed all the way up then it will grind. Also to answer your question the front and back are both suntour 3000

 

[black lightning 1987]

Right shifter and rear derailleur must both be Alpha 3000 to index correctly.

Is the noise coming from the front or the rear?

If the rear is shifting OK but you are getting noise from the front derailleur in certain gears you may have to trim the front a bit. It's also possible that the limit screws need adjusting. They need to be set so that the derailleur will shift onto both rings and can be trimmed enough to eliminate any noise caused by chain running at an angle to the rear. They also need to be set so that they don't allow the chain to be shifted off the outside of the big ring or the inside of the small one.