Originally Posted by
FBinNY
...If math isn't your forte, use a gear chart like
this one, to see the big picture of your gearing and choices.
Originally Posted by
fietsbob
44:11 and 48:12 is the same gear as 52:13, just arrived at by a different combintion, it's still 4:1
Thanks for the link very informative and great to see how I can accomplish similar output with different gear combos.
Originally Posted by
BCRider
So all in all if you find that you're not using the smaller rear sprockets then there really is no shame in switching to smaller rings on the front in order to both improve the chainline and to gain a wider range of USEABLE gearing options.
I love your advice because it lacks the macho side of things that we often see in cycling. This is exactly what I'm trying to achieve, more useable gears and a better chainline.
Originally Posted by
scruggle
I am surprised you get chain rubbing in 34x15 since '6th gear position' is only one off from the middle cog. I doubt this has to do with the size of your large chainring but a better description of the setup is the first step.
To be honest I'm not sure if it was 34x15 or 34x14 but it was there. I looked at the crankset manual it even says that there may be chain rub on the small chainring and 7th, 8th, and 9th cog. I took it too the LBS and he confirmed it was setup correctly and working perfect, it's just the way it functions.
Originally Posted by
fietsbob
46/34 is a reasonable 12 tooth difference , Spinners benefit from a bit easier gear
wider range cassette , Mtb derailleur 12-34
something close to the 34:15 [2.26] is 20~21 on the 46
I'll keep this in mind for the future. I'm 139lbs soaking wet thus I'm not a powerhouse and rely on a higher rate of spinning.
Originally Posted by
bobonker
Sounds like you might be happy with a 46/38 cyclocross crank. It's something I've been toying with. With the 50/34, there is a lot of rear D movement each time you move to the front D (to maintain or come close to maintaining the current speed).
Bob
I actually seriously considered this but with the hills here I need the lower gearing. As it is, the 34 is pushing it with some of the hills I commute on. I go down a hill at 40-45 mph and have to come back up that beast on the way home!
Originally Posted by
Sixty Fiver
You should not be having issues with chain rub if your bike is set up properly although it is always more efficient to maintain the straightest chain line possible for a specific gear.
By swapping to a 48 your top gear will still be 115 gear inches which is something the average rider is not going to push anywhere except down a hill for any distance... humans have a narrow power band and fairly fit humans can use gearings between 50-100 gear inches quite efficiently while lower gearing is good for hills and taller gears are best used in a paceline or on descents.
When you watch a guy like Contador doing a time trial he does not have his bike maxed out at 53:11 as that is 126 gear inches and you will see that he is most often running down a few steps in his range and probably living in that 90-100 gear inch range and spinning at a higher rpm which is far more efficient than trying to hammer a big gear.
46:11 is still 110 gear inches... if you can spin that gearing out you will have to be in great shape but it will be a nice gear for coming down those hills you have in Portland... which I have ridden up and down to excess.
Like I said up above in this post it does rub just like the manual says. I chalk it up to the design of the crankset...
and good points on gear inches. I hadn't considered this before. I'll have to keep this in mind as I continue to experiment with my gearing.