Transmission problems

[levad]

OK, bear with me as this is the most technical diy on the bike for me to date.

My gears won't change properly, I tried the cable tension and indexing business and it got a bit better but I cannot get into 50/12 and am finding that I am running out of gears.

I have a Tiagra transmission system (although the derailer says 105). The chainrings are 34-F and 50-F and the cassette on the back says HG 50-9 and the smallest gear is 12T. I looked on master Sheldons site and used the ruler method to check chain wear, the pivot for the 12th link is about 1/8th of an inch out, Sheldon says that the chain is worn and that I may need to change the gears as well.

I have two main questions and one open ended question:

1) What options do I have for the chain, do I need the Tiagra HG-53 chain or is there something more durable or better quality.

2) Can I go to a 52 or 53 chainring? I have just read another post about this but thought I would as anway!

3) How difficult is it to upgrade to 10 speed (e.g. full 105 but keep the Tiagra levers)?

Thanks all-knowing folk.

 

[grimpeur]

I am surprised you have checked your cable tension and chain wear first when the most likely reason you cannot change into top gear is something else.
your rear derailleur high limit screw would be the first thing to look at as adjustment of this screw determines how far the deraiileur moves towards your smallest sprocket. Loosening this screw(anticlockwise) will allow the derailleur cage to move further in the direction you want it to.

 

[levad]

The thing is, it did used to change into top gear. When I have the bike on blocks (makeshift bike stand) then I can change up and down, it is only under load that it is working. I put a new chain on yesterday, re-indexed the gears and can now get that top gear. I just found that I can also move the cranks from side to side, spoken to some bike guys here at work and they all seem to agree that I need a new bottom bracket

I am now looking at getting the Park tool a new BB and trying to do it myself