Can I put a compact ring on my double?

[ELL]

Hi all hope you can help and this isnt a stupid question.

Silly as this may sound I have been riding a double the on my commute bike the last couple of years thinking it was a compact (because thats what I was sold from the lbs). Been struggling with a hill on the way home that I can do fine on the other bike. Just got the wife a new bike with a compact and noticed a big difference in the sizes. Quick look on line an yep I have an ultegra double.

So my question is can I put the small ring from a compact (£20) on my double or do I need to buy a compact (£160).

Many thanks

Elliott

 

[smokeysmoo]

So my question is can I put the small ring from a compact on

Sadly not as the BCD measurement, (distance between the chainring bolt holes), differs from one to the other. You could put a different toothed double chainring on, but I don't know if you'd benefit enough as double rings don't go as low as 34T.

 

[lejogger]

As above, not a compact ring but it's often cheaper to increase the range on the rear rather than the front... What cassette are you currently running? A wider range block (up to 28/29) could be usually managed without changing your rear mech, or if you do need a longer cage, that's often cheaper than a whole new chainset.

 

[ELL]

I thought that may be the case. I will have to check the rear later but when I looked into it I thiworthad about the biggest as it has a short cage.

May look at selling the bike and get a new one as extream as it sounds. Just have no idea what its worth

 

[smokeysmoo]

May look at selling the bike and get a new one as extreme as it sounds. Just have no idea what its worth

That does sound a tad extreme ELL.

You could put a WANTED ad in the classified section for a compact, or @biggs682 and @accountantpete regularly have stuff for sale that could help.

As lejogger says, a new cassette could be the simplest fix though.

 

[fossyant]

Buy a compact and sell the double. A mate did this and the price difference wasn't much in the end.

Smallest you can fit to a double is a 38. New cassette should help - 28T is usually the max for a shimano short cage - you may need a couple of links extra, so budget a new chain when changing the cassette.

 

[HLaB]

If you are running campag I've found out their system accomodates a 29t cassette.

 

[Hacienda71]

You would need a 110 bcd to run a 36 or 34. A shimano double tends to be a 130 bcd which as said earlier in the thread will only take a minimum 38.

Sheldon has the info. Iirc Sram is the same as Shimano.

As Fossy says swap for a compact crank and sell on the double. Also check your front mech is ok with a compact.

 

[MisterStan]

PM sent....

 

[RecordAceFromNew]

I thought that may be the case. I will have to check the rear later but when I looked into it I thiworthad about the biggest as it has a short cage.

May look at selling the bike and get a new one as extream as it sounds. Just have no idea what its worth

As smokey said, changing bike certainly sounds extreme. It is most probably unnecessary.

The easiest and cheapest way to lower the gearing, for a road bike, is usually by changes at the back. Since you have an Ultegra chainset chance is you have a Shimano system, which if true means that you can use a Shimano mtb rear derailleur that is 9 speed or below (even if your bike is 10 speed), and which don't have to be expensive, to run a cassette up to 34T (and indeed potentially 36T). 34T rear and 39T front gives you roughly 30 gear inches, which should be low enough for nearly anything. Chance is you can live with less (and get closer ratios for cadence maintenance). You will likely need a new, longer chain if you increase the size of the cassette.

That is probably the worst case, in terms of ease and cost. I run a 32T cassette on a Dura Ace rear mech that has an official max sprocket of 26T with no issue whatsoever. This is a helpful guide on how.

Further not all compact chainsets are necessarily expensive. It might not look the business alongside a DuraAce or Ultegra, but as an example Stronglight 55 can be made up as a compact for peanuts with inexpensive JIS square tapered bb to pretty much any chainline one wants, and they are superlight. Or get one based on the XD2 or Impact.

As I mentioned in another post yesterday, it is best to figure out what is the highest low gear you want/need before figuring out how to achieve it.

 

[biggs682]

That does sound a tad extreme ELL.

You could put a WANTED ad in the classified section for a compact, or @biggs682 and @accountantpete regularly have stuff for sale that could help.

As lejogger says, a new cassette could be the simplest fix though.

@ELL sorry i have nothing at the moment

 

[ELL]

Thanks for all the advice. I think I will be changing to a 105 compact. Spoke to my local bike guy and he can do a new one for £145 fitted.

New bike was just a bit of a n+1as the wife has a new one.