Saturday, May 30, 2009

Seatbelt Improvement

All-in-all, I've found the Bakfiets to be well thought out and constructed. One area has always seemed lacking to me, though: the seatbelts for the bench in front.


There's a strap for each shoulder, coming together into a single buckle in the front that passes through the child's legs. The issue we've run into is that when the straps are adjusted short enough to fit my son's shoulders (he's 21 months), there's not enough room in the "loop" for his helmet to fit through.

This has meant that he has to go into the cargo box and be buckled before his helmet goes on, and the helmet has to be removed before he can get out. We like to cruise around the neighborhood on weekend mornings, and this has made it difficult to hop out for a few minutes to wander through a yard sale or pet a friendly dog. What a hassle! And every time that helmet goes on, it's another chance for a bad pinch by its buckle on his chubby little neck if I'm not careful enough. I don't need that kind of stress.

Enough was enough, it was time for a new strap. Browsing through strapworks.com, I found what I was looking for. A split release buckle would let me separate the shoulder straps. The factory belts themselves had always seemed a little stiff, so I opted for 1" seatbelt webbing for my version. And a strap adjuster would serve just as its name implied.

Now, if you were crafty enough, it would be a piece of cake to order the pieces and sew them yourself, but sewing isn't my craft of choice. So I spoke to David in the custom department at Strapworks. After faxing in a waiver that I wouldn't hold them responsible if anything bad happened, he gave me a great quote for the entire finished set. Each shoulder strap would be stitched to a strap adjuster, and the leg strap would be sewn to the bottom of the split buckle.

Three days after my order (they're not too far away in Eugene, Oregon), the straps arrived. I had ordered them extra-long so that I could cut them to size, but if you order your own and want to match the dimensions of the existing system, the shoulder straps need 30" of webbing and the leg strap needs just 8" (total length after sewing - add maybe an inch-and-a-half to loop back and sew). You could even order just the split-release buckle and its strap, and re-use the existing shoulder straps but threaded through the new buckles.

I removed the old straps and used them as a guide to cut the new ones to length, melted the ends on an iron to keep them from fraying, then melted a hole through the webbing with a soldering iron for the bolt hole. The new straps went right on without a problem. If I hadn't been taking pictures, it would have been around 5 minutes to do the swap.

Here's a comparison of the new leg strap (on top), and the old one:
And here are the new shoulder straps on top, compared to the old ones on the bottom:
Finally, here's the new belt installed:The boy is napping right now, so we haven't even had a test fit, but I'm sure it will work great. They buckle and unbuckle easily, and the belts are so much softer. I might even add some slip-on shoulder pads from his old car seat. What luxury!

4 comments:

Shane Rhodes said...

Awesome, so glad to read this. I live in Eugene and didn't know about Strapworks. Building up my cargo bike I'm going to need them to make my own strap system soon.

http://www.missyandshane.com/AllAroundUS/Creations/Entries/2009/1/29_Long_Haul_Box.html

markstos said...

Excellent write-up. I'll have to consider this upgrade now myself. I can just point Strapworks to this page and tell them to repeat the order. :)

Rusl Bicycle said...

Hi,

Thanks for posting this. Very Helpful to write all the details. I'm currently designing the seat belts for my unnamed cargo bike. http://www.bicyclefamily.ca/welcome/2010/11/milestone-first-test-ride-of-cargo-bike/ After having used your new seatbelts what is your verdict?

The main issue I have is also the helmet issue! My experience has come from using a Bakfiets. Also, we use our Bakfiets a lot, sometimes the bolt to the lower strap comes loose and falls off.

The CAT Oregon HPM seat belt doesn't use a split buckle, but two seperate buckles instead. What this means is the 4 straps (2 each side) can be mixed together to create a 3rd seating position in the middle, if you like.

I'm also going to put a strap between the two shoulder straps across the chest - similar to the chest strap on many backpacks. This is because sometimes the shoulder straps slide out off the shoulder. Lots of buckle options but you don't have to use them every time - but you can if you need.

I've also considered a 5 point harness like many car seats have but right now I'm sticking to the 3 points. I'm also interested in cushioning and headrests do you have any experience with that? When we bought our Bakfiets we were told there was an option to buy cushions - for like $200. I've never seen them or know any one with them.

Some friend's of our have a Bullitt with a box up front and have their 1 year old unbelted on a cushioned floor. Sounds luxurious but my wife and I are too safety minded to do that with our now 3 year old son (we got it when he was 5 months).

Take care and take the lane!

rusl

Nathan said...

Hi Rusl,

I still like the belts, but you're right that they need the strap across the chest so they don't fall off the shoulders. My son does a lot of twisting and turning—to look around or to talk to me—and I'm always reaching down to pull a strap back up to his shoulder.

We don't have cushions, but sometimes we'll fold up a small blanket to put on the seat. Our passenger was in diapers last year, so that was a cushion in itself. We'll see how he likes it this summer, and maybe I'll have to sew something. If I do, I'll be sure to post it.