Originally Posted by
Witterings
I've read through all the replies and a lot of it's gone straight over my head, I started cycling a lot more seriously about 1 1/2 yrs ago and have learnt an awful lot overall including bike maintenance etc. but as it was all on the one bike where the gearing happened to suit the riding we were doing so it's not an aspect I've needed to learn about until now.
I know the obvious is to shift to the smaller ring on the front which then also has the subsequent required shift on the rear as just changing the front on it's own is too much of a drop in gearing and you're just spinning out. The changes as mentioned are often for relatively short patches and you very quickly want to drop to higher gears / smaller cogs on the cassette and given that you can't use the 3 smallest cogs when on the small chainring on a 105 set you'd just be constantly changing the front ring with the associated changes on rear which I'm sure most would agree isn't ideal.
Interesting point I picked up on from GrainBrain's post .... generally for the same resistance through the peddles will smaller chainring and smaller cassette reduce your cadence for the same "feel" ... something else I've really noticed since having this bike is my cadence which used to be similar to the people I ride with is now considerably higher ... the others I ride with noticed and mentioned it even before I'd said anything.
Overall though and from Htupolev's comment .... unless I want to change the crankset to go much smaller on the front I'm probably not going to see a significant enough change to make anything else worth while which is a shame.
Gearing though is something I could obviously do with learning more about and what effect changes on the front will make vs changes on the rear etc. ..... does anybody know if there's a Dummies Guide to gearing anywhere as I' probably benefit from doing a bit of reading up on it.
Cheers for everyone's help so far!!!
Calculating gearing doesn't involve a lot of math but it can seem daunting. Alternatively, you can follow the Dunham rule...as in someone has probably already dun 'um for you.
This website has all the answers to your gearing questions and presents them in an easy to see formate. For example, going from a 48/32 chainring with an 11-34 cassette to a 46/30 chainring setup are
compared here. You are going from a 120 inch gear (or 120" wheel with the cranks connected to the axle) to a 115 inch gear. It's not much of a drop. A 115" gear is still pretty high for dirt riding. It's a good gear for pavement.
If you were to go to a
44/30 tooth in the front, you'd drop the high gear to 110" which is more reasonable. The smaller gap between the chainwheels also gives you a slightly smaller gap between the two ranges...although it is still rather large in my opinion.
I suggest you play with this application and see what is possible. It's easier than doing some arithmetic
