travelrobb

Hi all - our kids have outgrown their Woom 4s and are ready for new bikes. I like the quality of the Woom frames and essential components, but the drive train seemed under-powered from the start, the boys chug away in the smallest cog even on flat or slightly uphill terrain. To me, the front chain ring seems too small with 29 teeth, but the bigger Woom bikes have similar-sized chain rings. Woom says that the bigger wheels on the bigger bikes will resolve the problem, but I'm wondering if the kids should have bigger chain rings, too.

Woom says that the smallest sprocket on the Woom 5 is 63 gear inches and the gear inches of the smallest sprocket in the Woom 6 is 69 inches, compared to 53 inches on the Woom 4. So: does that difference seem significant enough to folks here? What is an appropriate gear inch range on a bike for 10-12 year-olds who ride frequently? (They typically ride almost 3 miles each day to and from school, and did a couple 10-mile rides over the summer.)

And if we ought to consider bikes with a bigger chain ring, which brands do people recommend for well-built, lightweight, and kid-considered bicycles?

Thanks,
Robb

autonomy

I'm not a gearing expert, but not sure there's such a thing as 'appropriate kids gear range' - sounds like Woom thinks theirs is appropriate, but your kids are just too athletic?
From Frog's website about gear ratios (front # teeth divided by rear # of teeth):
A ratio of 4 would be considered high and 2 would be low. Bikes with a ratio of 4 will be much harder to ride up steep hills than bikes with a ratio nearer to 2. Consequently, older or stronger children will be more comfortable riding a bike with a higher gear ratio.

https://en.wikipedia.org/wiki/Gear_inches gives some formulas for calculating speed based on gear ratios/gear inches, so you can do the calculations for the same cadence and different wheel speeds to compare how fast the Wooms can go.

Some other kids bikes to consider: Pello, Prevelo, Cleary, Priority, Frog, Islabikes (UK/Europe only), BYK, Woom, Spawn. Some review sites publish gain ratios, e.g. https://www.twowheelingtots.com/best...20-inch-bikes/ (CTRL+F for gain)

You could swap out the front cog to a larger one, but that may be a project beyond your interests.

chiefsilverback

I have 3 kids, 5, 7 and 9, and they are all keen riders. Right now the 9 y/o is on a 24" Pello Reyes, the 7 y/o is on a Frog 55 and the 5 y/o is on a Cannondale Quick 20. I'm in southern New Hampshire where ever ride involves a hill and I found the kids bikes want for climbing gears, so the first upgrade I made to all three bikes was to put on the widest range cassette I could find. That was an 11-40 for the Pello and Frog (9 and 8 speed respectively), and 12-32 for the Cannondale (7 speed). I subsequently upgraded the Pello with the Microshift Advent X drivetrain with an 11-48 cassette and a 32 narrow-wide chainring. I then moved the SRAM X5/7 9 speed to the Cannondale but run it as an 8 speed without the 11t because it's a 7 speed free hub. My 5 y/o would struggle with the grip shift, especially when it's hot and his hand was a bit sweaty so the trigger shift is much better for him.

Depending on budget you could look at the new Salsa Journeyman 24, or the equivalent Bombtrack, both drop bar bikes for 10 year olds. If you want to go more MTB, I've go a Nukeproof Cub Scout 26 on order for my oldest. No matter what bike you decide on, availability might be your enemy at the moment, so maybe a new chain ring is your only option.