Can I change from triple to double chainset?

LazyD

Hi,

I have this bike:

https://www.tredz.co.uk/.Scott-Speedste ... _73288.htm

The only real difference in the drivetrain is that I have a 10 speed Ultegra cassette instead of the 10 speed Tiagra it came with. I've always been really annoyed by the triple chainset, never been down to the small one ever, only go to the middle one very rarely, 97.3% of my time is spent on the big ring.

Can I change this 'Shimano FC - R563 Black Hyperdrive 50 × 39 × 30 T' out for something like a Tiagra or Ultegra double chainset, something like 50 / 34 ?? I would hope to be able to keep the bottom bracket (which is still smooth, no discernible bumps or grinds).

I understand that I would probably have to do something about the front derailleur, which is fine as it's not working properly anyway. If I have to swap that out for another and adjust the lever that would be fine.

The thing I would like the most is to be able to be on the big ring and not cross the chain when I go to any of the sprockets on the cassette, and then be able to go down to the smaller chainring and not be crossed as much as possible until I get down to the lowest gears.

I don't know much about all this, just wondering how the spacing would/could work to get the big front chainring roughly in-line with the middle of the cassette to achieve what I want. Can I get an off the shelf double that will just work and line up nicely, or would I need to get some sort of spacers / adapters involved?

Cheers!

veronese68

You can fit a double without changing anything else. Set the limit screws as necessary for the new chainset. Use the big and middle positions on the shifter, that way if you shift down too far you are just leaving unnecessary slack in the cable and not stressing anything. Not sure how your chainline will end up as I've not done it. Still best not to cross chain too much, avoid big/big and little/little.

trivial_poursuivant

Veronese68 wrote:

avoid big/big and little/little.

Even this is a non issue and many brands especially Sram see nothing wrong with it.

part time waster

I assume your bottom bracket width will be wider for a triple , I did this years ago and ended up buying a narrow bottom bracket for campag chorus double. your legs may still be wide apart with the triple B.B

slowbike

No problem with the BB - it's a standard HollowTech II .... so yes - you can just swap out the triple crankset for a double, set the mech limits appropriately and away you go ...

Or ...

I have a bike with a triple crankset - bought it for wet commuting - it came with a 32-11 cassette (9 speed) and I found I was never out of the big ring at the front, except for one climb where I dropped to the middle ring, but couldn't really find a comfortable gear for all the commuting route as 32-11 is quite wide spread - missing out a lot of ratios ... I changed it for a 23-11 - resulting in a much better use of the 3 chainrings and (more importantly) being able to find a suitable ratio for pretty much all the route.

Matthewfalle

Veronese68 wrote:

You can fit a double without changing anything else. Set the limit screws as necessary for the new chainset. Use the big and middle positions on the shifter, that way if you shift down too far you are just leaving unnecessary slack in the cable and not stressing anything. Not sure how your chainline will end up as I've not done it. Still best not to cross chain too much, avoid big/big and little/little.

This exactly

Matthewfalle

Trivial poursuivant wrote:

Veronese68 wrote:

avoid big/big and little/little.

Even this is a non issue and many brands especially Sram see nothing wrong with it.

And exactly as Trivial said.

keef66

part time waster wrote:

I assume your bottom bracket width will be wider for a triple , I did this years ago and ended up buying a narrow bottom bracket for campag chorus double. your legs may still be wide apart with the triple B.B

The triple chainset is wider because it uses spacers on the spindle on both sides; the Hollowtech BB is the same so leave it alone.

No spacers with a road double chainset, and as above, just set up the front mech again so it uses the shifter positions for big and middle ring. The chainline in the big ring will be better than it was with the triple.

The alternative is a new double front mech and corresponding left hand shifter, which is an expensive way of achieving what you want.

However, since you claim never to use the smallest chainring, why don't you just sort out the front mech / shifting so it works properly, and carry on using just the 50 and 39t chainrings? That's what I have on my best bike, and I'm occasionally glad of the 30t chainring at the end of a long day or if I encounter an unusually sharp hill or mental headwind.