Warning: I sound crabby in the stuff below, but really I'm just not very awake; I gotta get up in 5 hours for a 12-plus-hour day and can't actually fall asleep....
I said this in reply to your other thread, but: I pointed you to the list of threads about going 50MPH because that kind of thing really has been discussed to death, and people that want to do it need to read all those threads and not start another one about it--then they can decide if they still want to do it, and follow whatever advice they choose from those threads, and the many others with info like that that havent' yet been added to the list but should be relatively easy to find, by looking up members with fast bikes and reading their build threads and such.
I know--nobody wants to hear that their idea or need has already been discussed in detail so many times that everyone is tired of talking about it, and be told to search or given a list of suggested (or required) reading, but it happens to all of us at some point (happens to me a lot, which is why I poke around the forums and the web so much, cuz there's almost always at least one page somewhere that tells me why it's a bad idea :lol: )
In this case, it's a potentially really dangerous thing you're asking about, if not done right, and it upsets some of us more than others to see it asked about yet again. In my case it is because I think that if anyone is considering something dangerous, they ought to research it in depth first--either that or if they don't care they should just dive in and do it, and if they survive they should report back what they did and how well it worked (or didn't).
And if the person asking doesnt' even consider the idea to be dangerous enough to merit such reasearch, then it is unlikely they're going to listen to anything those of us concerned about them might say, anyway.
So, if you want discussion in this thread about it, keeping in mind that I've never ridden at that speed (around 40MPH downhill on a straight road (7th Street northbound at North Mountain, IIRC) of smooth pavement, keeping up with traffic, is about the fastest I've gone, on Crazybike2's original frame design before any motors were added). So my opinion is just that--opinion. If you want experience-based knowledge about it you'd have to read some of those other threads and posts.
Summary:
"What's the point of going fast enough to keep up with traffic to stay safe from traffic, if the vehicle itself is so potentially dangerous or failure prone at those speeds as to pose an even greater risk?"
Secondary Summary:
"Sure, you could do it safely, but to build it with bicycle components taht would do it, it'd probably cost as much or more as buying a motorcycle. Or you could build motorcycle components onto your bicycle, but then it gets so big and heavy that you might as well ahve started with one anyway."
I do understand about conditions there; here there are a number of places where it is simply unsafe to ride a bike, even though there is actually a bike lane on the road--and other places there's no way thru an area except on such an unsafe road, no shoulders, no sidewalk, no lane, and some parts of it only a single lane for 45MPH speed limit traffic that actually goes at least 60MPH.
I ride on some of those, only when I must, not by choice, but because there's no other path to get me where I have to go...but I have to do it at 20MPH and hope they don't mow me down, because if they kill me I don't have to worry about anything anymore--but if I get stopped for going faster than 20MPH it's probably more than $1000 in tickets.
For me, that's more than a month's pay. I live so close to the edge as it is that I'd be out on the street unless the landlord was really nice and let me just skip a couple month's rent, or basically always be behind by a couple of months, and not charge me late fees.
So I avoid such areas when I can. Sometimes it's not possible.
BUT: If I wanted to go fast enough to be safe, I wouldn't be doing it with cheap bike parts like I do now--they arent' sufficient.
Bicycle tires arent' going to last at those speeds, plus if you think a flat is bad at 20MPH, try a blowout at 50 on a bicycle tire. At least if you use DOT rated motorcycle tires the sidewalls are thick enough to not just stick your rim on the asphalt and skid you into traffic or a house. Maybe there's bicycle tires that cna do that, too...but I doubt they're reasonably priced.
Wheels, unless you get higher-end ones, probably quite expensive, aren't going to last under those conditons either. I can't imagine a department-store bike has wheels that could handle even a minor pothole at those speeds without turning into a pretzel, leaving you as strawberry jam under someone's wheels. I've had what seemed like pretty good wheels until at 15-20MPH I hit a bad pothole and it broke a bunch of spokes, pulled them out of the rim, or just dented the rim enough to be unrideably flat. None of them were high-end wheels, so you might get wheels you that would survive if you ahve the money...but you could buy used motorcycle wheels for cheaper. Even moped wheels would be better, most likely.
Brakes for department store bicycles generally aren't going to be designed for that kind of use, so stopping more than a few times (if any) with them is probably gonna be tough. And even if they are good enough to lockup the wheel, well, you still only have a (cheap) bicycle tire's tiny contact patch to get friction from on the road surface.... Maybe they'll modulate well enough to allow you to slow down without locking up, but I wouldnt' have any faith in that, based on my experiences with heavy bikes at lower speeds (20MPH or so), which is probably not even enough kinetic energy to match a lighter bike slowing from 50MPH.
The frame might be ok, since they often make them really heavy out of softer steel thicker tubing, should even give a little "suspension", but really I'd call it "frame flex" which makes it harder to control at higher speeds on bad roads.
Tehn there's suspension....the faster you hit a bump or a pothole, the more energy there is in the impact--and the better your suspension has to be to maintain control of the vehicle under that impact, especially on a lighter two-wheeled vehicle that is more easily deflected from it's path by the impact than a heavier one. Starts to get pretty expensive quick for bicycle suspensions that can deal with this...
If I was going to go that fast, I'd build a motorcycle, or what amounts to one, solely for the safety points.
I've only touched on the legal ramifications, based on some AZ police reactions to various assisted bicycles going even ONE MPH over the <20MPH limit imposed on them here. It doesnt' even begin to talk about what happens when a collision occurs because of something that fails at those high speeds, and someone gets killed (rider or passenger, or someone in anohter vehicle (unlikely unless it's another bike), or a pedestrian hit because the tire blew out or wheel collapsed on a pothole, and bike and rider were flung onto the sidewalk.... If that goes public and all the details start workign their way up the chain, how long before public outcry or political stupidity causes ebikes to be either banned or more likely limited into uselessness? Would force those of us that require more than such limits into becoming outlaws ourselves....
Anyway, there's an hour's worth of half-asleep rambling on the subject, with no objective facts (well, maybe one or two somewhere).
I also added this to the wiki itself, for those unwilling to read the linked stuff that's been discussed gone before, in far more detail than I went into, with pros and cons of each thing, opinions and facts from a lot of various members with varying experiences. Mostly because I didnt' want to have spent the hour or so I spent typing it up with only one person's thread "benefitting" from it. No one will have to search for it--they can read it whenever someone links them to the wiki about it.
