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hi all,

wondering if anybody had experience with combining compact gearing (50/34) with 650 wheels?

my felt - a tiny 43cm 650c machine - came with regular gearing due to the smaller wheel size. i am contemplating switching the gearing out from 53/39 to 50/34, but the jury is out on whether this is a good idea or not (Felt say it isn't, due to chances of spinning out)...

thoughts? experiences?

thanks!!
 

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Spinning out? Huh? My son has a 44cm with a triple (with 650c wheels). The small front ring is a 30. I don't see how the small ring on a double being a 34 is going to cause more trouble. The bike is fine. He doesn't have any problems "spinning out". We just did a big hill this morning. No issues at all (other than pain :cryin: :D ). When would anyone spin out anyway? Gravel under the back wheel? Leaning too far forward on too steep of an incline? These are issues with any bike. If you climb hills and you're not superman, compact is the way to go.
 

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My wife had a compact on her 650 bike and didn't really like the gearing. Nice on climbs but she did complain about spinning out on downhills. She's gone to a 700c bike and is much happier with the compact.
 

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simple...

A 650c bike is basically geared 1-cog lower that a 700c bike with the same crank and cassette. If both have a 53/39, then a 650c bike would need an 11-23 to work about the same as a 700c bike with a 12-25. If you switch to a compact, you can't get nearly as much top gear.

If the tire circumference is 1952 instead of 2110, the you have a reduction in gearing of 7.5%, which is slightly less than the average 1-cog shift.

A 50/11 top gear is in between a 53/12 and 53/13 on at 700c bike. If that 50/11 was on a 700c bike if would be a bit more top gear than a 53/12.
 

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wils70 said:
oh, and by spinning out i mean running out of bigger gears.
Okay. :blush2: I get it.

Then isn't the question just reversed? How many fast, steep downhill runs do you do? I guess it's kind of ironic that compact gearing that makes it easier to go up also makes it easier to "spin out' on the way down. So, which is most important to you? Fast ascent, or fast decent? Yes, I have a bike with 700 wheels, but I've never had any problems going scary fast downhill. Even with the loss of some gearing with the 650, I bet you can still manage white-knuckle fast. Also, of course, we all think about gearing and where we live. Where I live in Utah has tons of hills/mountains. I need/want fast ascents, decents, even when spinning out, aren't a speed problem.
 

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It's personal

wils70 said:
wondering if anybody had experience with combining compact gearing (50/34) with 650 wheels?

my felt - a tiny 43cm 650c machine - came with regular gearing due to the smaller wheel size. i am contemplating switching the gearing out from 53/39 to 50/34, but the jury is out on whether this is a good idea or not (Felt say it isn't, due to chances of spinning out)...

thoughts? experiences?
It really doesn't matter what any of us think, becase none of us can know how strong you are and whether you need the low gears this would provide or whether you really will spin out a 50/11. You need to relate back to your own experience about what high and low gears you need, and then do the extremely simple math to compare that gearing to what you would get with the 650/compact combination.
 

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650c wheels are about 7.5% smaller than 700C, assuming similar tire sizes. So basically, they turn 53-39 cranks into the equivalent of 49-36 cranks.

In other words, you kinda have a compact already.


/ I assume both wheels are 650C? 'Cuz if only the front one is, then your gearing isn't affected, obviously.
.
 

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Not to put too fine a point on it, but if the 34 seems necessary, it's unlikely that the 50 will be a problem.
 

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Try it yourself
http://sheldonbrown.com/gears/
The only 650s I've ridden were on my Cervelo P2 (tt bike), and it was plenty short for me. There's no physical reason why you can't do it, but change the cassette first - it's a lot cheaper than a new crank. If you have an 11-23 or 11-25, change it to an 12-27 and see if that gives you the extra oomph you need.
 
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