He's a major contributor, but mostly Paul has to design stuff, project manage stuff, give talks at events like Mission Workshop (keep reading, vids below), fix the dune buggy, and rip bathrooms out of the wall to make space for new machines.
But today, we do have an article from Paul - a piece of info straight from from the horse's mouth - to answer a question we get a lot. It's called:
Why You Can’t Use the Motolite Brake to Adapt a 700c Wheel to Your 27” Frame
And here it is:
We get a lot of questions about people having a bike they want to put a smaller wheel on. Sometimes it’s so they can fit a bigger tire, or sometimes it’s because they have a nice frame with an obsolete wheel size and want new wheels. This is the case for bike frames designed around 27” wheels. Many nice frames were built like this back in the day, so the need to keep them going is real.
Problem is, there’s very limited availability for good tires and rims in that size. Many of those frames were designed during the touring craze of the same era and thus have cantilever brakes. In the case of going from 27” to 700c, here are some words describing why it just doesn’t work, even though you really want it to. (You can cut the studs off your frame and use our Racer brake, but that is a different article.)
We make a brake called the Motolite, and it has a huge range of height adjustment for the pads. For example, you can put a 700c wheel on a frame designed for 26” wheels. That’s a difference of 32mm - handy! But here is the problem: 700c wheels are SMALLER than 27” wheels. The pad height adjustment range on the Motolites is typically about 5mm down and 35mm up. Ninety nine percent of the time the down range is not enough to work with the smaller 700c wheel.
But wait, you say. The difference in rim diameters is only 8mm. That means the radius difference is only 4mm! You said above the Motolite typically has 5mm downward range!
Well yes, the diameter of the 27”rim is 630mm, and the diameter of the 700c rim is 622mm. So 8mm or 4mm per side. The thing is, it all comes down to cantilever post location. Back in the old days, cantilever brake pads had rods that clamped them in position as opposed to the modern type with nuts. These brakes had a much larger range of cantilever boss locations they could be used with. (The modern nutted kind have a much more specific cantilever stud location.) Typically the studs (or canti “posts”) would be welded on much closer to the rim both vertically and horizontally. It didn’t matter all that much, the brakes themselves would work more than likely.
Back to that 4mm difference. You’ve got a really nice touring frame built in the 70’s and the canti studs are mounted 3mm higher than what is commonly used today in reference to how far vertically the post is from the rim. This is quite common. But if our Motolite has a normal 5mm downward range and the difference in the rim size is 4mm, that leaves 1mm of wiggle room with perfectly placed studs. But your canti studs are 3mm higher (again, pretty typical) than what’s normal now, so the pad needs to come down an additional 3mm. There is only 1mm left and boom, you’ve hitting the pivot/spring part of the brake and the pads won’t go down any farther.
And that’s why you can’t put 700c wheels on a bike designed for 27” wheels and cantilever brakes.
Have a good ride,
Paul
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