Upgrading a mini road bike
So I found this cool little road bike at a garage sale, and I've built it up for my son to ride. It's a little Pinnacle FS 5-speed, with a little lugged steel frame. I have a feeling its standard 70s hi-ten tubing. It came with 20-inch steel 451s, and the rear rim had a flat spot. I grabbed some craigslist BMX 406s (sealed bearings!) and put 20x1.5 Contis from the LBS recumbent specialists. I dug in the used bin for BMX brakes to reach, and luckily found some. Pretty much overhauled it completely with new cables and pads. Yanked the pie plate and tossed on a BMX bash guard to keep him from hooking up his jeans. I'd like to eventually get rid of the cottered cranks by swapping out the BB. Not sure how ambitious I am about that yet. My son is in heaven zipping around on that thing, and yes, he likes the drop bars (now taped and capped) with suicide levers. He gets a lot of attention in this bike-centric town (Portland OR) Here's a pic.
Now I haven't messed much with bikes since my childhood, when I took apart every bike I owned. While riding casually over the years, I've learned the basics. Since this is still a kids bike, I don't want to throw too much money at it. There's the younger brother in line too who will give it good use. Now however, I'm going to attempt for the first time to lace up some used Sun ICI BMX race 451s to slowly upgrade a bit at a time.
So finally to my question. . . can anyone suggest an inexpensive 36-hole hubset to lace to these rims? I was hoping for a used set of older Shimanos from the used bike shops bins, but I'm not that familiar with models--Aceras? Deores? The original spread was around 120mm with a threaded cassette. I'll probably have a pro dish and true the rear.
Any tips or advice greatly appreciated. Sorry for the long-winded question
, and thanks in advance.