Standard double to Compact or semi compact

[philtalksbx]

So in a mad phase, I swapped the 34 for a 40

I went to a 1x9 with a 40th from a vintage double and a 12-27th 9 sp casette. Also went flat bar with a Tiagra shifter. For west London general purpose runaround / winter commuter it works so well. Few real hills here so I don't often pine for more range. On the looks and dirty trousers front I swapped the big ring for a Stronglight chainguard, well worth it.

http://www.spacycles.co.uk/products.php?plid=m2b0s149p2381

 

[Nigelnaturist]

I went to a 1x9 with a 40th from a vintage double and a 12-27th 9 sp casette. Also went flat bar with a Tiagra shifter. For west London general purpose runaround / winter commuter it works so well. Few real hills here so I don't often pine for more range. On the looks and dirty trousers front I swapped the big ring for a Stronglight chainguard, well worth it.

http://www.spacycles.co.uk/products.php?plid=m2b0s149p2381

40x27 is lower than 38x23 and like I said it gets me up 10% without to much trouble if not to long, I would find the 40x12 about right as I don't spin much quicker than 25mph on the flat, in fact I had a 40x12-27 set up and really liked the range, but hated the gaps from 17-19 and 21-24-27 but on a single front it would be great.

 

[Citius]

Depends if you can spin the 27 quick enough for it to be quicker, the point I am trying to make is that compacts leave you wanting in gear ratios between having a low enough gear to get up the most difficult hill you have to do and a high enough gear to maintain a good speed, my average non zero cad is about 86rpm and my average gear at that is 61" (said I wasn't fast) but having a close grouped cassette coupled with three front rings is far better for many than a compact 34-50, I know as @cyberknight said I would be toward either end of the cassette, as it is these days I am tending toward the higher gears on the cassette on 38th front, simple because I changed from the 12-27 to 12-23 and whilst on the 12-27 I would climb mainly on the 38x24, I have had to up it a little on the 12-23 which as you say has made me fitter, not by fitting ever bigger cassettes but by fit a smaller one.

The other advantage is you will always have the right gear, sometimes you find one gear is to high one is too low, especially when its windy.

Compacts, per se, don't necessarily leave you wanting an 'extra gear', any more than a standard 52/42 or 53/39, as it depends entirely on personal preference. I've been using 12-25 and 50/38 for years - for racing, training and general riding. I've never felt like I needed a gear in between any of the ratios I currently have.

 

[Nigelnaturist]

Compacts, per se, don't necessarily leave you wanting an 'extra gear', any more than a standard 52/42 or 53/39, as it depends entirely on personal preference. I've been using 12-25 and 50/38 for years - for racing, training and general riding. I've never felt like I needed a gear in between any of the ratios I currently have.

Depending on how many rear gears you have a 12-25 can have pretty tight ratios, take the 11sp 12-25 (12-13-14-15-16-17-18-19-21-25) or a 10sp without the 18th so they won't be large gaps, its that 18th that I wanted for the way I ride, my front is much the same as yours being a 50-38-28, bear in mind my bike is not the lightest at 12.5kg+ I weigh 12 1/2st or so at 6ft, I have come to the gear ratios I have by trial and error not because someone told me what is right or wrong and that is what everyone should do.
I often read of people starting in cycling getting a compact because its the thing to ride having a low front 34th ring, however many a time I then read these people looking to put bigger cassettes on the back because they can not get up the hills, well a 34 front can only go down to a 1:1 ratios with a 34 rear, even on an 11sp thats leaving some pretty big gaps in the ratios, where as a setup like I have has the best of both being a pretty normal double ok not a 52 (but it could take one 28-40-52 I know would work) but for me that 40th front and 23 back is probably a little long for my general riding, you come to these conclusion over time, and by not being afraid to experiment, I have run both 8 and 9sp with a 13th high gear so I could set up a 13-14-15-17-19-21-23-25 or the 9sp with a 16th in there, all ratios made up from different cassettes 9 and 8sp cogs are interchangeable providing you use the right sp spacer, shifting is not always 100% but it is acceptable if not racing ect...