105 5703 or Tiagra 4703 chainset

cygnusx04
cygnusx04 Posts: 6
in Workshop
I've an old bike from 2007. The bike is running an old 10 speed 105 groupset (shifters + derailleurs + cassette) but with a Triple FSA Gossamer chainset which needs replacing (rings and crank). I've just purchased a Tiagra 4703 chainset (175 cranks) which comes out at 1139 grams in weight. The BB is an RS500 which is compatiable.

My current FSA chainset is 979grams. (~160grams lighter than the Tiagra).

I've just discovered I can get a 105 5703 triple chainset for £30 more and its weight appears to be under 800grams!

The bike is for sportives and commuting. I'm torn between the newer heavier Tiagra vs older 2011 105 lighter chainset.

For the hassle of sending back and reordering should i really be worrying here or just fit the Tiagra and get riding :smile: And no - I am not upgrading to 11 speed.

Comments

  • whyamihere
    whyamihere Posts: 7,702
    I would go for the 105. Saving 300+ grams would normally cost a lot more than £30.
  • cygnusx04
    cygnusx04 Posts: 6
    thinking about it.........if I needed to replace any of the chainrings. Guessing they'd be alot easier to get hold of for the Tiagra?
  • whyamihere
    whyamihere Posts: 7,702
    cygnusx04 said:

    thinking about it.........if I needed to replace any of the chainrings. Guessing they'd be alot easier to get hold of for the Tiagra?

    I'd actually guess there wouldn't be a lot of difference. Tiagra uses a 4 bolt setup, which Shimano switched to a few years ago, and is only used by Shimano. If you would only be buying official Shimano rings, that's fine, but a new set of Shimano rings can cost about the same as buying a whole chainset. However, the 105 used a 5 bolt 130mm bcd (I think) setup which was shared by basically every crank manufacturer, meaning that you have a huge number of aftermarket chainrings to choose from.
  • cygnusx04
    cygnusx04 Posts: 6
    thanks you are right.

    105 5703 uses 5 bolt 130 bcd
    Tiagra uses 4 arm 110 mm bcd
  • cygnusx04
    cygnusx04 Posts: 6
    From what i can tell the 105 has hollow cranks which may be a little stiffer and lighter.
    I ride around 4000 miles a year, but metal is metal so would assume durability of rings should be the same?
  • whyamihere
    whyamihere Posts: 7,702
    I'd expect similar durability from the rings, yes.

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