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Calculating gear ratios: http://sheldonbrown.com/gears/

 

Select gear units to inches and put in your chainrings (put in 52, 42 and 39) and cassette. When you calculate it will show you how far in inches you go per gear combination. Make an exel sheet and compare against each other. One interesting thing is how much overlap there is between the large and small chain ring.

 

For example, 39 x 13 = 81.0 inches while 42 x 14 = 81.0 inches as well.

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When you calculate it will show you how far in inches you go per gear combination.

 

Does that mean you go forward eg: 40 inches (1016 mm) in distance for a certain combination? When doing the comparison the 39/27t combination gives a variable of 39.0 while the 42/28t gives a figure of 40.5. Doesn't seem like a massive difference but I'm wondering how much harder it will be to push that on the 42t????

Edited by Bianchisti
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How big is the step up from a 39t to a 42t? The cost difference is about R1000 cheaper for the 42t. Is it worth trying to save the money or am I going to feel the going to tough on the hills for a mid pack Argus finisher? Is it an idea to go up to a 28t on the cassette to compensate??

 

Hi,

 

I currently use the old setup which is 52-42 and I can tell you this, it all depends on your fitness,strength and riding style. At the end of the day, the 39 tooth will help you keep a good cadence which will help you on the climb basically preserving power for when you hit the big blade.

 

You could use the 42 blade but then change the rear cassette to a 28 tooth like you say. In fact, I would say use a 12-26 cassette.

 

What time are you aiming for?

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First, the reason cassettes have gone from 7 to 8,9,10 and now 11 - is so that the spacing between gears is smaller. example gears go from 11,12,13,14,15,17,19,21,23,25 - So adding another 28 tooth gear means a new ratio. Probably 12,13,14,15,16,17,19,21,23,25,28 - depending on what your lbs has.

 

If you don't need your 11 (or12) whatever you have, and you can maintain a tight ratio on your cassette - 13,14,15,16,17 etc then ok to add the 28 but the 23,25,28 gaps are big.

Much better in MHO to go 39 on the front and keep the back jumps between gears as small as possible.

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Hi,

 

I currently use the old setup which is 52-42 and I can tell you this, it all depends on your fitness,strength and riding style. At the end of the day, the 39 tooth will help you keep a good cadence which will help you on the climb basically preserving power for when you hit the big blade.

 

You could use the 42 blade but then change the rear cassette to a 28 tooth like you say. In fact, I would say use a 12-26 cassette.

 

What time are you aiming for?

 

Yeah the strength and fitness (or lack there-of) is exactly why I’m asking. I’m almost always on flat roads and usually ride at an average cadence of 90-100 so I think the 42t will actually give me a bit more choice and benefit. It’s only when I’m gonna be doing the Argus that I will really need the 39t and the granny gear. As far as riding style is concerned i generally padel at quite a high cadence.

 

Why would you recommend the 12-26? I’m trying to lightened the workload not increase it???

 

The 42/28t gives a ratio of 40.5. I might have to go climb some hills on the 39/24 (ratio 43.9) I have on at the moment to get an idea of what it might feel like.

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Simple. With your last Argus or any ride did you use your biggest rear sprocket. Changing to a 42 in front will limit your range in the back in terns of lighter gears. If you are in your small blade in front and shifting down to your small sprockets you can just as well switch to your big blade and use bigger rear sprockets. Stick with the 39.

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