Just returned from a 170km mass-start event which was on a very hot day (25DegC+ temps). I had done all my prep work ahead of time, including getting the bike transmission adjusted well. Cables stretched, mech's lubed, chain cleaned and dry lube'd, a lot of grease applied over the plastic cable guide under the bottom bracket shell, etc.. Everything was working well. After about 4 hours in, the shifting started to get sluggish with no down shift at the start of some climbs. All very frustrating.
The bike is about 5 months old and everything is in pretty much as-new condition. I have found that after about one month of ownership the initially fault free operation of the transmission would start to get sluggish. I put this down to the new cables starting to stretch so took care of that.
This is my first 10-speed setup. Its 105 STI shifters, Tiagra front (50-34) and 105 rear (11-28). Honestly, I am finding it to very temperamental in general with fault-free shifting only lasting for about two or three training rides. Basically, I need to look for a fix for the next event. Short of just buying new equipment, what should I be looking at in terms of setup and maintenance? The way things stand, I don't have confidence with this for anything beyond 4 hours or so. Could there be something that needs to be looked at with the STI shifters? They never seems to be mentioned when there is talk about gear change issues? I say this since in addition to the rear issues, I found that the front downshift to the 34 ring would need an almighty push as a light click would do nothing later-on on the ride.
By the way, I don't want to use the C word, but I am a fan of a certain Italian component manufacturer