Comment by jakecodes
4 years ago
Hi Jacques! A little late here. It's cool to see someone else spot welding! For the DC area, it's totally faster to commute and I took my daughter everywhere! Now we're in Philly and I use it for long ranges. I've built a bunch of these in various forms, my favorite is a big wheel scooter. It's my main commuter. Look up rivet nuts for securing to the frame! Was a big life saver.
One thing: After years of riding various bikes I've built, please for the love of everything, be careful at high speeds because I've discovered the weakest point of the bike is the C shaped thing at the end of the fork for the wheels. At super high speeds the bumps are rougher on the bike and will eventually pull it apart, even with mid motor power. It may not even come apart all the way, but spread open slightly. Maybe millimeters.
I've tried several bikes, offroad and everything. It won't happen now, but like at odometer 6000 or something. Every single time it fails there. I've had 3 bikes, various scooters, all fail that way. It means your wheel may eventually, suddenly come off at a high speed. I think the answer is a custom fork, but haven't gone there yet.
I'm jakecodes on twitter if you want to trade knowledge.
Hi Jake, I love this kind of response, all the armchair lawyering and other bs is just a huge distraction, there are exactly four comments in this whole thread including yours that are constructive. You mean the metal part joining the two sides of the fork? That's a great warning, I never thought of monitoring that bit in particular but now that you mention it that makes perfect sense, there is quite a bit of force on that joint.
I'll go and have a look at my bike right away and I'll keep a sharp eye on this as well.
And you've got one more follower in Twitter :)
Do you have any pictures of those failures? I'd love to see what they look like to get an idea of where an early warning might manifest itself.
I looked up the names for the parts of the fork: It's the part of the fork called the dropout that fails. Here's a picture of a dropout itself: https://i.stack.imgur.com/VZ8bO.jpg, not mine.
When it fails it may look exactly the same (you won't see anything wrong), if you take calipers to it, you'll notice the gap has widened. So measure it now and remeasure every once in a while. If it's changing you've got a problem.
OR you may be able to see it is visibly slightly wider, like more bowl shaped. It doesn't take much for the wheel to come off, it's very tight tolerances. I've never had one snap yet, but I've heard of other's whose dropouts have snapped.
You will notice it is starting to fail when you brake and the wheel feels like it is shifting ever so slightly. It might make a tiny little clink sound. Sometimes it will make the wheel clink around in the dropout when you go over bumps, since the tolerances are SO tight in that area.
It's not just stretching the C towards a straight line that happens, but also twisting at that area or flattening from side to side movement.
Ever since they failed on me a few times I've been riding less because it's a problem I have not solved yet. I reinforced them with 1/4 inch steel. Still it moved independently.
One other solution I've heard about to get bigger tires, they are often called "fat tires". That dampens the stress on the bike a lot. It also makes for a much smoother ride. But I've not done that yet since fat tires need space in the fork. I think a stronger fork and fat tires may totally solve the problem. Fat tires would be nice because it'll turn your bike into a nice smooth ride, and you know how rough the ride can be at that speed for that long.
I've got 2 1/4" on there right now, and those drop-out pads are massively overengineered on the Riese & Mueller bikes but I'll keep an eye on that anyway.
You could get a thru axle fork and wheel. It's supposed to be much stronger and rigid-er.
While I've never seen/heard of this happening, I suppose it's possible. I'd chalk it up to 2 issues: 1) possibly not tightening the quick release skewers quite enough 2) cheaper aluminum dropouts on the suspension lowers. One solid option is to purchase a thru-axle fork and wheel. They're becoming pretty much the standard across the cycling/mtb industry and you can even find rigid steel options (https://surlybikes.com/parts/karate_monkey_fork). If you're replacing your fork, that'll also open up options to buy a larger rim & higher volume tire to absorb more impact. Generally speaking, thru axle forks are designed to take a lot of abuse, so you'd be hard pressed to overstress one in a commuting setting, even over a long period of time.
You can also try a bolt on hub/fork where you're actually tightening a hex nut to secure the dropouts on the axle—most older 10 speeds are in this vein. They're also typically steel which is always nice for reliability.
I electrified a Kona Unit last year as a car replacement and have put it through the ringer. If you like tinkering, I highly recommend poking around the forums on lunacycle.com.
Good stuff, I've always been very kind to my bikes, avoid impact on the rims if I can (no kerb hopping, always aiming for the least impact if there is an obstacle on the road). Even so, with these bikes and the mileage they make (my brother wears out a frame every couple of years) it's probably a good idea to up the monitoring rate on the frame, especially at all the weld and high stress points. I've never had a frame fail - yet - in spite of many km on all kinds of bikes but that has also turned this into something of a blind spot so that warning is definitely a good one.
Look for thru-axle, they're standard on gravel-oriented bikes and mountain bikes, and are getting onto more and more of the road oriented bikes.