Chainrings on a CX bike.



uffstuffson

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Aug 1, 2013
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I am extremely new to cycling. I currently just bought my first bike since I was around 13 (I'm 27 now.) I purchased a Cannondale CAADX 105 from my LBS beginning of the week and will be picking it up Saturday. I've been reading recently about different crank sets and was curious what everyone has to say. The CAADX 105 currently has a 46/36 crank set and a 12-28. A friend of mine has a synapse which has the same rear but a 50/34 crank set. We are both at about the same fitness level. Am I going to have problems keeping up? If so would it be possible to put some sort of 50 or 53/46/34 crankset on the CAADX or Is that just a newbie question? I read a post about a 50x11 being 123 gear inches (not sure what that is in MPH?) would changing the rear cassette to something with an 11 tooth chain ring be more beneficial? Possibly a 50 or 53 big ring in front with an 11 in back? I'm more curious how much more speed I would be getting or is it just splitting hairs? How much faster could the same person get going with a 53x11 vs the 46x12. I suppose my real question is how much will I be held back by the lower gearing. If it's a significant amount what can I do to fix that mechanically on the bike. I am also curious about how big of a difference there is with the gear ratios of say 46x12, 50x12 and 53x12 and how much an 11 tooth chain ring would help. Tons of questions and I may have just puked them out all at once. Lol thanks to anyone that decides to tackle this tangled web of questions! Brent
 
Widely accepted wisdom states that most people do well at a cadence(=rate-of-turns at the cranks) between 80-100 RPM(turns-per-minute)
This will get an average MTB into a top speed of +25 MPH.
A CX bike with about your gearing, having higher gearing and bigger wheels than an average MTB will get you well past 30+MPH - assuming you're fit enough to turn the cranks.

So, as long as you're below 30 MPH, any troubles keeping up is due to the motor - you - and not the bike.

As long as you're below 30 MPH, worry about stamina and pedalling technique, not bike technology.

If you do a lot of riding past 30 MPH, you should be on a road bike, and in a team, riding for money.

If you want to tinker around, here's a link to my favourite site:http://www.sheldonbrown.com/gears/

Input your bike specifics, then to show MPH@100RPM and hit calculate.

Keep in mind that many people find it easier to work on strength than stamina and pedalling technique, so asking about how to up the gearing ratio is a common thing.
But riding is far more about stamina than strength, so performance-wise, it's pretty much a dead end.
Just have a look at the road riding pros, chunky thighs isn't exactly the first thing that comes to mind.
Pretty much the only ones with any muscle mass to them are the sprinters.
And pushing hard-and-slow is a lot worse for the knees than pushing light-and-fast, so you're not making yourself any favors that way either. Rather, you're putting yourself at risk of injury pedalling hard-and-slow.
 
Originally Posted by dabac
So, as long as you're below 30 MPH, any troubles keeping up is due to the motor - you - and not the bike.

As long as you're below 30 MPH, worry about stamina and pedalling technique, not bike technology.

If you do a lot of riding past 30 MPH, you should be on a road bike, and in a team, riding for money.
Thank you! I am definitely ignorant on the pace I will be moving at. Sounds like I will probably be significantly <30mph as a beginner and shouldn't have to worry about over riding the hardware that comes with the bike. Wish I had the experience and was good enough to ride on a team for money! lol
 

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