jjjj

I am still having trouble with my sons Sora Triple. When I am in either the big or middle chain ring and on the largest cog in the rear the chain drops down a chain ring in the front. This does not immediately occur when shifting to the large cog, but does happen consistantly. It looks to me that the front does not line well enough with the back.

I checked the chainline and it "appears" to be aligned when in a middle middle configuration.

I have adjusted the rear derailleur.

The front derailleur is not causing the drop.

I am considering whether the chain is long enough and taking another look at chainline.

Any ideas?

Thanks
John

sydney

It's obvious you shouldn't be in the big/big/. If the middle/big is also casuing a problem,that is easy enough to avoid too. If the BB/crank is factory, it's unlikely the chainline is off.Rather than guess, pull the crank,measure the spindle and compare to what is speced.A sora square taper triple uses a 113 spindle and the new octalink version uses a 118. The chain is long enough if the big/big does not gink anything or overextend the RD cage.

jjjj

Thanks for the reply. I did some comparisons to my ultegra 9 speed triple and the measurements all match. Not sure that has much validity, but it seem like a good idea. I am going to pull the chain and check that it is the correct length and see if it has any stuck/sticky links. With it off i will also check out the RD setup. Although I am fairly confident it is at least ok. If you have any other ideas let me know thanks again.

John

sydney

You don't have to pull the chain to check for correct lenght. You can check for sticky links by getting into a chainring \ rear cog combination that gives a reasonably straight chainline, and pedaling backwards and watching the RD for 'jumps' or other anomalies.

jjjj

Thanks, I'll try both.

jjjj

Fixed, I adjusted the front derailleur, so it rubs a liittle on the large cog in the middle chain ring or big chain ring. Good remainder that it is time to shift. Chain is no longer dropping. Thanks for your input. I was on the way to big stupid changes.