Saturday, February 7, 2015

Surly Straggler kids' bike

Ever since Surly announced that the Straggler would be available for 650B wheels down to 38 cm frames, I've been scheming to build a bike or two for my kids. Well, my scheme finally came to fruition yesterday.
With disc brakes, there's no mechanical reason not to use other wheel sizes, so I chose to use 26" wheels instead of 650B. This improves stand-over clearance by about one inch. Standover at mid-top-tube is approximately 68 cm or 27 inches.

One concern with using smaller-than-spec wheels is pedal strike. If the bike is lowered too much by using smaller wheels, the pedals can strike the ground in corners, which can cause a crash. Since my 9-year-old daughter is only about 4'2" (125 cm) tall, I decided that typical "short" adult cranks (typically 165 mm) would be far too long for the biomechanics of her kid-sized legs. After consultation with my friend Mark at Bikesmith Design, I decided to follow his rule-of-thumb that crank length should be approximately 10% of the rider's height (or 23% of inseam). Ten percent of 125 cm is 125 mm. Bikesmith has a thriving business shortening cranks, and within 24 hours, he delivered a set of shortened SRAM S600 cranks with 125 mm arms.
By the way, lots of people can benefit from crank lengths that are shorter than the industry standard 165 mm length. If you have short legs, or suffer from knee or hip pain or other range of motion issues, or ride in an unconventional position (aero position), I strongly urge you to discuss the benefits of short cranks with Bikesmith Design.

Even with the tiny 38 cm frame size, smaller wheels, and short cranks, the bike is still marginally too large for my daughter, who is shorter than average for her age. Standover clearance is tolerable, but the reach to the bars seems pretty long. I found a short stem (60 mm) and a riser bar with a bit of sweep.
I think kids (and adults) who are new to multi-speed bikes benefit from a simple drivetrain and some kind of display that indicates the gear number. Cheap SRAM twist shifters and a 1x7/8/9/10 drivetrain accomplish this. And, by the way this bike has Shimano M396 hydraulic brakes. These are great brakes for a relatively small amount of money. I selected these because they are actually substantially less expensive than decent mechanical disc brakes and levers. The added benefit is that hydraulic brakes can be actuated with a light grip, perfect for a small kid with small hands.

She took it for a ride around the block and didn't even slip on the ice. The bike fits great (better than I expected), and she looked pretty fast and confident on it. Happy kid!

Total MSRP for a bike similar to this is in the neighborhood of $1400 plus tax (less for me, because I have insider hook-ups and lots of spare parts). Seems like a lot of money for a kid's bike, but I believe she will get my money's worth. With minor adjustments, she will likely ride this for many years (possibly through high school or longer), and if/when she outgrows it, one of my younger kids can ride it. Or I can sell it, because it's a brand that has good name recognition and resale value. But the best justification is that she will have a high-quality cycling experience that will (I hope) forge a lifelong love of bikes and cycling.

6 comments:

Mart Stonich said...

I wanted to clarify that 10% of height or 23% of inseam would produce a length too long for adults. It is only appropriate for growing children and will be good for 2-3 years.

Anonymous said...

At 9 years old I believe a bicycle with 24" wheels would be more fitting.

Mark Stonich said...

Many of my short crank customers have built bikes for their kids using 24" wheels on bikes designed for 26". Including a couple of fat bikes. However finding appropriate wheels is a major problem.

A bigger issue is top tube length. But the right bar/stem combo can usually compensate.

Too bad there aren't more good quality bikes designed around 24" wheels for kids & small adults.

Anonymous said...

You could always use a bar like the Nitto Dove to get the bars back further. She will probably grow into that bike in no time!

Anonymous said...

I AM A CHEESEBURGER!!!!!!!

Bikes For Kids said...

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