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Discussion Starter · #1 ·
Obviously finding a kids bike with an XD hub is hard...but these e13 cassettes are precisely why it's a good idea for OEMs to move on to XD some day. The idea that you could get this much range without a big pie plate (which doesn't work with short cage RD's), on a little kids 20/24in wheel is pretty dang awesome!

I'm not sure how they shift (is that 9cog shift any good?) but I certainly like the idea. 9 - 42 sounds pretty dang sweet. Thats a 466% range vs a 11-42 which has 381%. Couple that with a 28t or even 26t chainring and that'd be pretty decent I'm guessing. They have a 9-39 too.
 

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The small 9 tooth cogs don't wrap around as nicely. That said they'd hardly use the 9t, especially given their strength and the degree of decline. Also, e13 cassettes have their problems...
 

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Why is it important for a 9 tooth cog on the kids' bike?

Not judging, just asking why they would need that low of a gear. And the wide range of 9/42. I get the 42 for sure though.

Is the front ring pretty small too? Or is the overall gearing pretty low just because of the smaller tire size making a 9 tooth more likely to be used.

Thanks for sharing your thoughts.
 

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Discussion Starter · #4 ·
It's just the range. No different than adults wanting to go with Eagle or XTR. The idea that 9 is better for kids is that most kids bike wheel tires are small and can't use a longer cage RD so they get less gearing range than an adult yet have weaker muscles/stamina. I'm under the impression that it's be nice to have that range, especially for 20in wheels (9x 34) and just run a small ring up front. My kid def spins out on his 20in with 30t ring on some jump lines but often it's not used a ton. Slap head is prob spot on for most.
 

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I looked into the e13 cassettes for myself recently. The number of reports of fast wear and bent cogs made me decide against it. That may not be a problem on a kids bike, but a SRAM 10-42 is definitely the safe play.
 

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Discussion Starter · #7 ·
I looked into the e13 cassettes for myself recently. The number of reports of fast wear and bent cogs made me decide against it. That may not be a problem on a kids bike, but a SRAM 10-42 is definitely the safe play.
Roger that. I'm just going to do what you are doing Dan lol. Have you decided on a 24" yet? I'm guessing you will have a sweet option or two!
 

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Why is it important for a 9 tooth cog on the kids' bike?

Not judging, just asking why they would need that low of a gear. And the wide range of 9/42. I get the 42 for sure though.

Is the front ring pretty small too? Or is the overall gearing pretty low just because of the smaller tire size making a 9 tooth more likely to be used.

Thanks for sharing your thoughts.
the 9t isn’t a low gear, it’s the highest gear.

Going 10% (vs a 10t Xd cassette) or 20%(vs a standard cassette with 11t small cog) smaller for the smallest cog, lets you go 10% (or 20%)smaller for the chainring and biggest cog as well, while keeping the exact same gearing.

This is important for kids bikes because the small wheels put the derailleur closer to the ground. So running a 46t cog, let alone a 50t cog on a 20 or 24” wheel is not good.
For this reason, on my daughters 24x2.6 bike, I chose to run an 11-40 cassette, instead of 11-46 or even 11-50, because the derailleur would have been to close to the ground.
To a lesser extent, the same holds true for the front. A well designed kids bike has a low bottom bracket. This is no problem for them for pedaling because they should be on short cranks anyway. However, If you start putting big chainrings on there, you increase the risk of bashing the chainring.

The other thing is that the smaller cassette and chainrings will be lighter. Always a benefit for kids bikes.
 

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the 9t isn’t a low gear, it’s the highest gear.

Going 10% (vs a 10t Xd cassette) or 20%(vs a standard cassette with 11t small cog) smaller for the smallest cog, lets you go 10% (or 20%)smaller for the chainring and biggest cog as well, while keeping the exact same gearing.

This is important for kids bikes because the small wheels put the derailleur closer to the ground. So running a 46t cog, let alone a 50t cog on a 20 or 24” wheel is not good.
For this reason, on my daughters 24x2.6 bike, I chose to run an 11-40 cassette, instead of 11-46 or even 11-50, because the derailleur would have been to close to the ground.
To a lesser extent, the same holds true for the front. A well designed kids bike has a low bottom bracket. This is no problem for them for pedaling because they should be on short cranks anyway. However, If you start putting big chainrings on there, you increase the risk of bashing the chainring.

The other thing is that the smaller cassette and chainrings will be lighter. Always a benefit for kids bikes.
Oops, yes I mispoke calling the 9t low gear.

I just typed it incorrectly. Thanks for catching that.
 
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