Safe speeds on non-suspended, 20" front wheel, LWB recumbent

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Safe speeds on non-suspended, 20" front wheel, LWB recumbent

Postby doughpat » Thu Apr 20, 2017 3:38 pm

Hi everyone-

As I obsess over motor/battery/controller configurations, I constantly come back to the question of, "How fast do I want to be able to go?".

And unfortunately, there isn't really any way to know what X mph feels like on your specific bike on a specific road in a set of specific conditions until you try it. Since that's an expensive/dangerous way to learn, I thought I'd ask you all.

I have an EZ Racer "Tour Easy" LWB recumbent. It has a 20" front wheel (700cc rear), no suspension. Schwalbe tires. How fast would you say a reasonable person (with dependents!) should try to go on this bike?
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Re: Safe speeds on non-suspended, 20" front wheel, LWB recum

Postby flat tire » Thu Apr 20, 2017 5:19 pm

Faster than you want to go in it. I'm sure it'll handle 40+ no problem human riders reach those speeds and faster racing 'bents.
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Re: Safe speeds on non-suspended, 20" front wheel, LWB recum

Postby RyanT » Thu Apr 20, 2017 5:49 pm

Honestly I would think 35 mph would be a good speed depending on where you live. I say 30-35 just so you can get out into traffic on a city street when you don't have a bike lane. It makes you much more confident in those situations.

I've generally been going 20-25 mph on my commutes/and joy rides as it's a comfortable riding speed. You don't have to and won't go flat out all the time, but it's nice to have the speed when you need to use it.
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Re: Safe speeds on non-suspended, 20" front wheel, LWB recum

Postby MadRhino » Thu Apr 20, 2017 7:02 pm

Safe speed is according to one rider on one course. Many factors could make speed unsafe, the size of the wheels has little to do with it. What I would consider is: how stiff and straight the frame, how true the wheel, how good the brakes... then the obstacles and the surface quality. If all of those were perfect, I would ride as fast as it can. :twisted:
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Re: Safe speeds on non-suspended, 20" front wheel, LWB recum

Postby Rassy » Thu Apr 20, 2017 7:13 pm

I had a LWB Vision R40 recumbent bike, 26" back wheel and 20" front wheel prior to going all trikes. The previous owner of the Vision claimed a downhill coasting speed of 59 MPH. My brother claimed a downhill coasting speed of 60 MPH on his rear suspension Burley SWB recumbent. These were both pedal only bikes at the time.

Those speeds were way to fast for me and I probably never rode the Vision much over 30 MPH.
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Re: Safe speeds on non-suspended, 20" front wheel, LWB recum

Postby Ianhill » Thu Apr 20, 2017 9:05 pm

If the tyre is of concern you can use a 16 inch moped tyre on a 20 inch bicycle rim its rated for high speeds, loads and will fit a stock rim, mopeds use the tyres ID dimension and bicycles the OD, Ebike hotrodders swap their outer rim over to a aluminium moped one with heavier spokes and a meaty 15/20kw hub motor.

I suspect there will be tyres rated for the recumbent speeds, the 20 inch tyre in contact with the road will be pulling 100's of g's at 60+mph An anodized metal valve cap may weigh as much as a bag of sugar with centrifugal forces acting on it thats why I always use stock plastic valve caps on anything with tubes they keep dirt out of the valve and are as light as possible, A good choice would be flush fit valves for cleaner air flow and use the rim for valve stability at crazy high speeds no one wants a blow out at any decent speed let alone 60 mph next to the ground I suppose a recumbent can have a roll over ?
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Re: Safe speeds on non-suspended, 20" front wheel, LWB recum

Postby amberwolf » Fri Apr 21, 2017 2:02 am

doughpat wrote: How fast would you say a reasonable person (with dependents!) should try to go on this bike?

How good are the brakes?

How well does it stop from various speeds, meaning how controllable is the stop under various conditions?

That's probably your most important limiting factor--if you can't stop safely and easily from a certain speed, you probably don't want to be going that fast. ;)

If you're not sure, try testing it out on downhills without any traffic, etc., with straight stops, stops while turning, etc., and see how it works from various speeds, both with sudden stops and slow decelerations, etc. I recommend good thick multilayer clothing and/or joint padding and a good helmet for this kind of testing. ;)


The good news is that most typically a crash (for me) at speeds below 40MPH on CrazyBike2, like when I was on the racetrack for the Death Races in Tucson, it results in a sideways skid, rather than an endover, but that depends on the reason for a crash.

But if i'd been unable to stop quckly enough and rammed into a car or whatever in front of me, most likely it'd've been an endover and I'd've been launched into the air at a high speed over or into whatever I'd hit. That kind of crash is likely to only happen below 20MPH for me becuase that's the speed limit here, but I don't know how fast you'd end up going or what the limits are there.
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Re: Safe speeds on non-suspended, 20" front wheel, LWB recum

Postby Chalo » Fri Apr 21, 2017 11:22 am

amberwolf wrote:How good are the brakes?

How well does it stop from various speeds, meaning how controllable is the stop under various conditions?

That's probably your most important limiting factor--if you can't stop safely and easily from a certain speed, you probably don't want to be going that fast. ;)


That's a particularly good point to make for a LWB recumbent, where the light front wheel loading promotes front wheel skids in hard stops. I had problems with front wheel skidding on my chopper bikes that carried almost all the weight on the rear wheel; even relatively modest braking of the front wheel could cause loss of control when the wheel slid in a direction other than the one in which it was pointed. The moral of that story is that the rear brake becomes more important, and the front brake riskier, the more of the total weight is located over the rear wheel.

As for the OP's question:. Tire width is a factor. The wider the tires-- up to a point-- the more traction and shock absorption they provide and the faster you can go. Even the seat and how much shock isolation it offers makes a difference in what speeds are feasible.

But the biggest single factor, and the one beyond your control, is the quality of your riding surface. Almost any bike would be okay at 60 mph on a smooth, banked, well-maintained velodrome. But take a poor-to-average street surface and add some deep potholes and sandy patches, and you'll need a pretty special bike just to do 30mph safely.

The lightly weighted front wheel of your 'bent is both a blessing and a curse:. On one hand, the low weight bearing makes the small wheel diameter less treacherous when encountering holes or obstacles. On the other hand, any shortcomings in traction will be magnified by the same low front wheel loading. Front wheel skids are hard to recover from, and more likely to cause a crash than rear wheel skids.
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Re: Safe speeds on non-suspended, 20" front wheel, LWB recum

Postby Warren » Fri Apr 21, 2017 1:45 pm

I use one finger on the front brake of my LWB, mid-drive. I mash the rear for all it's worth. I will outstop an upright, no problem.
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Re: Safe speeds on non-suspended, 20" front wheel, LWB recum

Postby The fingers » Fri Apr 21, 2017 1:53 pm

Rassy wrote:I had a LWB Vision R40 recumbent bike, 26" back wheel and 20" front wheel prior to going all trikes. The previous owner of the Vision claimed a downhill coasting speed of 59 MPH. My brother claimed a downhill coasting speed of 60 MPH on his rear suspension Burley SWB recumbent. These were both pedal only bikes at the time.

Those speeds were way to fast for me and I probably never rode the Vision much over 30 MPH.


A short steep hill is a good way to test it faster than you can pedal. A speed-induced death wobble not a good idea though. :wink:

When we were kids we used to go down Airplane Hill in Signal Hill. Then they re-engineered it to make it less steep and ruined all the fun by installing a stop sign halfway down. :(
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Re: Safe speeds on non-suspended, 20" front wheel, LWB recum

Postby ecycler » Fri Apr 21, 2017 3:45 pm

Warren wrote:I use one finger on the front brake of my LWB, mid-drive. I mash the rear for all it's worth. I will outstop an upright, no problem.


If that is your braking technique, then I will bite...

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I challenge you to a "Stop-Off!" duel on one of my uprights! :mrgreen:

Your call on the rules, but I say it goes something like this: Both bikes travel 40mph side by side and hit the brakes at a designated line. First person to stop wins. I have a closed course we can use and $100 cash money to make it fun. 8)
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Re: Safe speeds on non-suspended, 20" front wheel, LWB recum

Postby Chalo » Fri Apr 21, 2017 4:22 pm

Chalo wrote:The wider the tires-- up to a point-- the more traction and shock absorption they provide and the faster you can go.


There's a related point I forgot to mention. The heavier the front tire, the more gyroscopic stability it will exhibit, since precession force tends to automatically correct the seteering in the appropriate direction. So a heavier than necessary front tire in this case might be a good thing, making the bike steadier and​ more comfortable to ride at high speed.
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