What is the maximum speed you would ride a fully rigid bike/moped?

[ebike4healthandfitness]

Normally I would say 30 mph. This mainly because under heavy braking (with sticky tires) I can see my front hub pulling rearward (essentially steepening the head tube angle) during which time the top tube is experiencing heavier than normal tension forces and the down tube is experiencing heavier than normal compression forces.

If that could be fixed I might be willing to go over 30 mph on a closed course. This assuming, of course, the bike is also sufficiently balanced and low center of gravity (e.g. think shorter than normal cranks to allow lower BB height while still allowing sufficient ground clearance).

Some examples of fully rigid bikes and fully rigid mobility devices going very fast would be Tour de France riders going downhill (60+ mph ) on those very narrow high pressure tires. Another example of fully rigid going fast is the Rion RE90 electric kick scooter which is 80 mph (only requiring part throttle) on very small diameter wheels.

 

[Stealth_Chopper]

Me? ~ Thirteen MPH . I've ridden motorcycles and you need suspension & 'the more the better' to go faster.
you yadayaya till "If that could be fixed I might be willing to go over 30 mph on a closed course. This assuming, of course, the bike is also sufficiently balanced and low center of gravity."
YOU hit a a Tour de America chuck hole and get old fashioned launched.

 

[ebike4healthandfitness]

Me? ~ Thirteen MPH . I've ridden motorcycles and you need suspension & 'the more the better' to go faster.
you yadayaya till "If that could be fixed I might be willing to go over 30 mph on a closed course. This assuming, of course, the bike is also sufficiently balanced and low center of gravity."
YOU hit a a Tour de America chuck hole and get old fashioned launched.

I have also ridden motorcycles. Not all of them have suspension. Google "fully rigid motorcycle".

 

[Az.]

I wouldn't ride it at all.

 

[offGridDownUnder]

What's chasing me?

 

[neptronix]

20-25mph is the most i'd be willing to tolerate. We don't have nice roads here, so..

My main problem above 25mph on a bike is hitting an irregular shaped surface with the front wheel and having it land in a place i didn't expect and have to do a quick correction. This is unsafe.

Find myself staring at the road trying to avoid imperfections too much without good suspension. Not an enjoyable ride.

Front suspension and a smooshy seat / suspension seatpost? if i lean on the front, 30mph is as fast as i want to go.

 

[ebike4healthandfitness]

Here is one source of information on rigid forks for motorcycles:

rigid forks

 

[neptronix]

Notice the mentioned forks are ultra long and at something like a 45 degree angle. This means they can act as a form of suspension in themselves. But in terms of suspension ability, a 3-5lbs entry level air shock fork on a bike would perform better. And learning forward as much as possible would make that front fork more effective ( and also help aerodynamics, because humans are far from aerodynamic! )

 

[ebike4healthandfitness]

Notice the mentioned forks are ultra long and at something like a 45 degree angle. This means they can act as a form of suspension in themselves. But in terms of suspension ability, a 3-5lbs entry level air shock fork on a bike would perform better. And learning forward as much as possible would make that front fork more effective ( and also help aerodynamics, because humans are far from aerodynamic! )

Not all rigid forks are long. Some are normal length and put the rider in a more forward position:

 

[999zip999]

46mph on E-50 rated bicycle tires.

 

[docw009]

I've never thought much about the bike collapsing on me, Where I ride, the safety issue is cars pulling out or getting doored. And of course, weak brakes.

I would expect though that my bikes can be ridden safely to the high 20's (,mph). That's probably inherent in Consumer Product Safety Commission standards. If you ride the rail-trails in Colorado, you're going to be at those speeds going downhill. Seven years ago, we came down from Copper Mountain on our department store beater diamondbacks, lightly riding the rim brakes to stay under their 25 mph speed limit. We were keeping a low profile because ebikes weren't allowed at that time. Damn signs everywhere,

I wonder what terminal velocity is on a downhill rail trail (4% grade)) with an uprught rider, Probably not much more than 30 mph?




.

 

[Papa]

Normally I would say 30 mph. This mainly because under heavy braking (with sticky tires) I can see my front hub pulling rearward (essentially steepening the head tube angle) during which time the top tube is experiencing heavier than normal tension forces and the down tube is experiencing heavier than normal compression forces.

If that could be fixed I might be willing to go over 30 mph on a closed course. This assuming, of course, the bike is also sufficiently balanced and low center of gravity (e.g. think shorter than normal cranks to allow lower BB height while still allowing sufficient ground clearance).

Some examples of fully rigid bikes and fully rigid mobility devices going very fast would be Tour de France riders going downhill (60+ mph ) on those very narrow high pressure tires. Another example of fully rigid going fast is the Rion RE90 electric kick scooter which is 80 mph (only requiring part throttle) on very small diameter wheels.

Bicycles were never originally designed to exceed speeds much higher than about 20mph. As improved tires, brakes and minor steering changes were implemented, speeds increased only slightly. Much higher than around 15-18mph, aerodynamic drag becomes the dominate factor to overcome.

Given the average speed ridden around 17-20mph (usually through trial & error), the bike's ballpark wheelbase was established. A WB much shorter than around 45", resulted in too sensitive steering response, while a longer WB produced 'subdued' or reduced sensitivity.

The point, is that nearly every aspect of the common 'bicycle' has an effect on its handling... at the intended speed.

Unless you intend to haul cargo, little can be done to improve the bare-bones bicycle's center of mass (CoM) location. After all, 75% of the bike and rider's gross weight, is the rider. Other than simply stacking the rider on top, there is no other reasonable choice. Ideally, the optimum CoM location, is at or near the bike's longitudinal roll axis. NOT too low (it's NOT a car), nor too high, in reference to the surface being ridden on.

 

[ebike4healthandfitness]

Bicycles were never originally designed to exceed speeds much higher than about 20mph. As improved tires, brakes and minor steering changes were implemented, speeds increased only slightly.

Of the things you mentioned, IMO tires are the greatest limiting factor.

Because bicycle tires are lightweight the rubber is in general not very sticky.... otherwise it would wear out too fast.

Non sticky tires mean there is only so much a person can do to improve braking and handling through components and frame design.

 

[Papa]

Non sticky tires mean there is only so much a person can do to improve braking and handling bicycle's brakes

The century old braking problem on bicycles has little to do with increasing tire grip AND chosen brake design (disc, rim, drum). One needs to look no further than the poor CoM location and short wheelbase. Just how high you fly the rear wheel is most telling - it's the visual limit - telling you, you are AT the max deceleration rate possible.

 

[kuromaku]

I personally settled on 40kph for typical gravel geometry drop bar frame sets in town, and ~60kph for long front-center geo, reverse mullet setup to increase trail. Still sketchy unless I know the roads well...

 

[ebike4healthandfitness]

The century old braking problem on bicycles has little to do with increasing tire grip AND chosen brake design (disc, rim, drum). One needs to look no further than the poor CoM location and short wheelbase. Just how high you fly the rear wheel is most telling - it's the visual limit - telling you, you are AT the max deceleration rate possible.

Yes, the rear tire lifts up when the front brake is applied.

But besides CoM what is contributing to that?

On a bike with a typical suspension fork it is the compression of the fork itself that worsens "endo" while selecting "fork lockout" reduces "brake dive" and "endo" under hard braking.

P.S. BMW solved the problem of brake dive on their motorcycles with the Telelever and Doulever suspension fork design. Because of this bikes with these suspensions are able to brake more sharply than usual without suffering from the effects of "endo" you are talking about.

 

[ScooterMan101]

I now have a long wheelbase rigid recumbent as one of my bikes , with schwalbe e-bike tires , going down mountain roads , coasting with no motor power I often hit 35-38 mph and it is quite relaxing compared to other bikes . I was surprised at how well it handles higher speed.
I am in the future
going to put a longer travel front suspension fork on my other bike to better handle speed . ( More Slack and a little more wheelbase )
Ever see the Tour de France and some of the mountain roads they go down ? , it is easy for a bike to get up to 40-50 mph going down hill .

 

[ebike4healthandfitness]

Ever see the Tour de France and some of the mountain roads they go down ? , it is easy for a bike to get up to 40-50 mph going down hill .

They actually go over 60 mph at some places.

More impressive to me is the fully rigid very small diameter tire Rion RE90. I've seen you tube videos of that one near full speed on the freeway.

 

[ScooterMan101]

I love watching the Pro's go down those Mountain Roads , I would love to see some on the bike video footage of that as well .

 

[ebike4healthandfitness]

Here is some footage of the Rion RE90:

 

[raylo32]

I have done ~55 Mph on my road bike here many times back in the day on club rides in our local mountains on 17 pound rigid road bikes with 23mm tires. But you have to know the roads for the pavement condition and where the intersections/driveways are and have a good runout. Because emergency hard braking at that speed on a rigid bike with skinny tires is a recipe for disaster.

I have one CYC X1 pro e-bike on a double suspension MTB with 2.1" tires and XT hydro brakes that is very secure braking even at 40+ mph... and potholes and other pavement issues that would have unhorsed me on the road bike are trivial on the suspension bike. Just point it and go.

 

[Jeff23spl]

Here is some footage of the Rion RE90:

Those are crazy. I just have a modded blackrat going at 30mph and i don't see how i could handle much more...I'm thinking about how i could improve it to 35-40mph but my main actual problem is tire balancing. those tiny tires are probably made for manually pushed chariot or kids rides. When i took the middle shaft of one in a vise, you can see the heavier side of the tire turn back down...I did try to add weight internally to help it but it get tricky.....The one doing 80mph probably got something better than what i have....i bought new one to see and it is the same...

 

[neptronix]

Hope that guy has good health insurance and a will written out.
No sane person goes that fast on wheels that small.

 

[99t4]

Not sure what you are trying to find out from your question but I get into the low-mid 40s MPH range going down local Wahoo Hill on my Radwagon v1. longtail cargo bike hardtail/hard fork running 26x2.35 Schwalbe Big Apples. When conditions permit (traffic, road conditions, weather, etc.).

Cruising feels pretty good up to its controller-limited 26 MPH. Longtail provides a well balanced F-R platform with the rider pretty much in the center, which seems more like a pivot point rather than a launching pad, better than sitting directly over the rear wheel. So it likes to take a set and plow on thru.