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8 Posts
Discussion Starter · #1 ·
Hello all,

I ride a Trek 5500 full dura-ace 10sp and a Trek Fuel 100 full suspension MTB

I have a commuter bike for the city a Trek T30.

This is the navigator equiped bike, triple crankset and 7 speed cassette with grip shifters,
The rear derailer is a shimano acera and has Tektro v-brakes

This is an european model so I guess it is not avaliable in America.

here you have the specs

However it is a very nice city bike, with aluminum frame and well equiped, I absolutely hate how this bike switches speeds. The rear derailer, changes cogs when I am climbing or even when pedalling hard and I am on the handlebars.

It is maybe normal for a bike on that price level, but it is really annoying and I keep comparing it with my racing or MTB bikes that shifts speeds smoothly and never fails me on climbs or sprints.

So I decided to upgrade it.

I have 2 choices.

  1. Upgrade the shifters, cassette, rear derailer and chain to Deore LX
  2. Change the whole drivetrain for a Shimano 105 groupset

So my questions are.

for option 1:

The front crankset is a 7 speed, would it work with a 9 speed drivetrain ? Or I have also to change the shimano TX71 48s/38s/28s crankset for another ?

for option 2

I could change the whole drivetrain to a Shimano 105 group I can get at good price. I would also then change the flat handlebars to a road handlebars and install the shimano STIs.

Actually this option is what I would like most, I love the racing handlebars and generally dislike the flat handlebars.

But, would the STIs work with the V-Brakes ?
If not, Can I install the 105 brakes with the 700x35c wheels and tires?

Thanks for your answers

114 Posts
There is no excuse for a bike ot auto-shift (unless its deisgned to). Lower end drivetrains will have lower quality shifts, especially when under load but should remain in gear when not shifting.

It sounds to me like either a derailleur adjustment is in order or you threw a new chain on a well-used cassette. If your not a profecient mechanic a trip to the LBS would be a good start.
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