'fairly' novel design
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Forum Name: Building
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URL: https://forum.bhpc.org.uk/forum_posts.asp?TID=6509
Printed Date: 27 March 2026 at 2:18am
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Topic: 'fairly' novel design
Posted By: bob walton
Subject: 'fairly' novel design
Date Posted: 24 June 2017 at 2:34pm
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Some people have told me that there is nothing novel here. A head set that leans backwards isn't new, and neither is using a linkage from the handlebars to the front wheel. But I haven't seen one like this and I was actually really happy the way it turned out. You can never tell when you start a project if it will finish up OK. Here it is anyway. The local lads around here said it was 'sick', which is apparently yoof speak for good. 'Bad' also means good, also 'wicked'. I digress.... http://youtu.be/49kxtAL8tPA" rel="nofollow - http://youtu.be/49kxtAL8tPA
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Replies:
Posted By: GeoffBird
Date Posted: 24 June 2017 at 6:08pm
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Looks like it handles well Bob. There were some Dutch low-racers that had a reverse rake head tube and remote steering but I can't remember what they were called. There is a Velo Vision article about them somewhere...
Here is my design with a vertical steering head and remote steering:   ------------- Right Time - Right Place - Wrong Speed |
Posted By: bob walton
Date Posted: 24 June 2017 at 11:21pm
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blimey, that's a fabulous looking thing. I was trying to keep mine a simple as possible and just use off the shelf components. I thought a very soft seat might be simpler than suspension but its a bit harsh when you go down a curb. I think you were aiming higher than me! Are you happy with the way your bike goes? Is it easy to ride? And what will you make next, or do you think this is this the pinnacle? If I did another one I would try to lighten it instead of just using square section mild steel - and do a boingier seat. I like simplicity, but your build quality puts me to shame. ------------- funnyfrontend |
Posted By: GeoffBird
Date Posted: 25 June 2017 at 6:53pm
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Thanks Bob. Many aspects of the design work well, but over all I'd say it is a bit of a failure. It is very heavy and pretty slow. No doubt the fairings I had planned for it would make it quicker but I'd rather start from a more efficient base. I'm not clear yet why it is slow but simplicity and light weight are always preferable in a bicycle. Your design looks very usable as a medium to short-range machine. Suspension is nice - hard to go back to a bike without it, especially with the road surfaces around here! ------------- Right Time - Right Place - Wrong Speed |
Posted By: legs_larry
Date Posted: 26 June 2017 at 12:18pm
And closer to home there was Dave Richards' Kestrel, which was just about the sweetest-handling bike I ever rode. ------------- ==================== a bit ov a lyv wyr by slof standirds |
GeoffBird wrote:Posted By: GeoffBird
Date Posted: 26 June 2017 at 3:59pm
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Yes, I forgot that one Dave, although that had a vertical headset IIRC. Fiona owned Sherri's sister bike to DR's machine for a while. I found it a bit twitchy, but I replaced the steering joints with some better ones which helped a bit. I also rode a one-off that Peter Ross built with the same setup. Then there was the Streetglider from Future Cycles in Winnie the Pooh country, which I never rode. All these bikes (including mine) display very steady low-speed handling (walking pace) and a lack of tendency to fall into corners that recumbents with conventional steering geometry have. But cornering-wise, a 10 degree head angle works even better (Derrick's Fast Donkey and my T-7 - both with direct steering), with most of the low-speed benefits of a vertical head angle. Of course, these conclusions are subjective and based on a low sample. The remote steering adds weight, complexity and can get in the way of your legs (as on my T-9, pictured above, although it has a fairly low Q-factor). For these reasons, my next one will probably have direct steering but with as steep a head angle as possible without introducing too much tiller effect. I find bikes with lots of tiller effect (big offset between hands and steering axis) very unpleasant - You have to be in a Zen-like state to ride them smoothly...
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Posted By: bob walton
Date Posted: 26 June 2017 at 6:40pm
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I've googled some of the bikes you mentioned but can't see one that looks like mine, even if some bikes have some of the same features. I thought it was simple and easy to get on with. ------------- funnyfrontend |
Posted By: GeoffBird
Date Posted: 26 June 2017 at 8:24pm
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I certainly can't think of any long wheelbase bikes with a reverse rake head tube. Mike Burrows' LWB Ratcatcher had a vertical head tube. There was a production LWB bike designed by a German professor that had a very similar layout but conventional steering geometry (but rubber band suspension), but I can't for the life of me think of the name of it. You'll have to bring your bike along to a BHPC meeting so we can have a go Bob. ------------- Right Time - Right Place - Wrong Speed |
Posted By: bob walton
Date Posted: 26 June 2017 at 8:29pm
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where's that then - and when? ------------- funnyfrontend |
Posted By: GeoffBird
Date Posted: 26 June 2017 at 8:54pm
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http://www.bhpc.org.uk/events.aspx" rel="nofollow - http://www.bhpc.org.uk/events.aspx ------------- Right Time - Right Place - Wrong Speed |
Posted By: GeoffBird
Date Posted: 26 June 2017 at 11:19pm
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Ah, the name came from deep in my unconscious :-) Radnabel http://www.radnabel.com/atl-modelle/falter/details/" rel="nofollow - http://www.radnabel.com/atl-modelle/falter/details/ http://www.youtube.com/watch?v=xZgX6zIViBY" rel="nofollow - https://www.youtube.com/watch?v=xZgX6zIViBY http://www.youtube.com/watch?v=fsBEvBX_S4o" rel="nofollow - https://www.youtube.com/watch?v=fsBEvBX_S4o
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Posted By: bob walton
Date Posted: 01 July 2017 at 9:38pm
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I am thinking of popping round to your meeting tomorrow in Shrewsbury just to see what the crack is. i will bring my bike. cheers, bob ------------- funnyfrontend |
Posted By: atlas_shrugged
Date Posted: 02 July 2017 at 10:23pm
| I enjoyed riding your bike around at Shewsbury. It felt very stable and I liked the very good turning capability. Thanks for bringing it along. |
Posted By: bob walton
Date Posted: 02 July 2017 at 11:21pm
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It's nice of you to say so. I must admit that was a fascinating experience for me. I have never been up close to bikes that before, and I really learnt a lot - friendly atmosphere, and the sun even came out. I can see I am a bit of a beginner here. I'll just have to raise my game ......again! ------------- funnyfrontend |
Posted By: GeoffBird
Date Posted: 03 July 2017 at 11:26am
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Glad you made it to an event Bob. Sorry we couldn't be there. We had a bad night's sleep and couldn't find the energy to get up early... ------------- Right Time - Right Place - Wrong Speed |
Posted By: bob walton
Date Posted: 04 July 2017 at 12:11pm
By the way didn't really think the Radnabel bike looked the same. The headset was the normal way round with direct steering. Maybe my front end is 'actually' novel, rather than 'fairly' novel??  ------------- funnyfrontend |
Posted By: Balor
Date Posted: 02 March 2018 at 11:16am
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I can attest that negative steering angle (if you add remote steering, of course) results in very nice handling characteristics, a small negative angle is likely better than Burrows-suggested 90deg steering because of a unique combination of positive trail and *negative* wheel flop. To be fair, you can have a similar effect by installing a strong return to center spring - that is what, actually, negative angle does in a way. It does come with negatives like having to incorporate lots of negative offset and hence being unable to use conventional suspension forks, plus braking hard or hitting a pothole may bend your forks unless you make them really strong. It has much more merit for MBB actually, but making remote steering on MBB is really, really hard due to huge 'pedal feedback' forces involved.
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Posted By: bob walton
Date Posted: 02 March 2018 at 12:55pm
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Adding a spring to the steering isn't the same as using a negative rake. The spring force will depend only on the angle the wheel is turned to the side. The 'correcting' force here depends on how off balance you are, and it turns the steering to correct the imbalance. It's way better than using a spring! Also, the forks don't need to be mega-strong as you suggest. There isn't as much weight on the front wheel as there is on a normal bike because most of the rider's weight is on the back. There is much less weight shift when you brake too. That means you never finish up with all your weight on the front wheel when you brake hard. And the forks are shorter than on a normal bike so the bending moment (force x lever arm) tends to be smaller. These three effects mean that the forks don't need to be extra strong. In fact, I used forks from a kids bike and I have gone over lots of pot holes without braking anything. If you did want suspension, do it like this... http://youtu.be/ECzFlrXNry8" rel="nofollow - https://youtu.be/ECzFlrXNry8 This is an off-the-shelf swing arm and off-the-shelf shockers, just like a normal twin shock rear suspension, but fitted to the front with a big pivot. Everything is completely conventional  ------------- funnyfrontend |
Posted By: Balor
Date Posted: 02 March 2018 at 1:47pm
I'm sure if I follow... which 'correcting force' do you have in mind? Trail and camber torque? Those are present in conventional designs, this is why DF bicycles are self-stable. Negative wheel flop? As much as I understand, it is simply a case stable equilibrium, hence - 'return to center' force, unlike unstable equilibrium of conventional wheel flop. Weight distribution? Negative offset and some tiller does not help, actually. Can your design be self-stable like DF bike on this video? https://www.youtube.com/watch?v=Zt7J0dly70M" rel="nofollow - https://www.youtube.com/watch?v=Zt7J0dly70M
Yea, admittedly those are not a problem for your particular implementation (lwb). I'm was talking on general principle.
Well, extending this logic, every bike is just conventional pieces of metal fitting together :). I mean you cannot just take off the shelf telescoping fork and expect it to work.
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Posted By: bob walton
Date Posted: 02 March 2018 at 3:56pm
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Yes, it balances like a normal bike. The way this happens is actually quite complicated because there are gyroscopic and other dynamic forces at work here too, but I will try to explain in simple terms. If you let go of the handlebars on a normal bike at standstill, the steering will tend to turn fully to one side (Wheel flop it's called). But on a bike with negative rake it will tend to straighten. This is a stabilising effect because you want the wheel to point the way you are going. But if you are going round a corner of constant radius at constant speed, the steering has to be turned slightly to one side. On a bike with a negative rake the steering will not try to straighten the way it would if it was centred by a spring. And you don't want it to straighten because you are going round a corner of constant radius. To prove that it works watch this video...
https://www.youtube.com/watch?v=lgJjgRtKNT4&feature=youtu.be ... where I ride an earlier version of the same bike no hands. You can't normally do that on a recumbent. Yes, any bike is just a bunch of metal parts. But that's a bit like saying a face is just a bunch of features. It's the way the the features are arranged on the face that distinguishes one from another.  ------------- funnyfrontend |
Posted By: Balor
Date Posted: 07 March 2018 at 7:17am
Negative rake AND "negative" head tube angle. Simply going for a negative rake on a conventional angle will only make flop much nastier due to proportionally increased trail.
That might very well be. I've read 'motorcylcle dynamics' by Cossalter and I admit that some parts are way too complex for me to understand fully, but I will eventually experiment with a spring and see how it compares.
Well, 'self-stability' is thing that you either have or your don't. Being able to ride no-hands, however, is mostly a rider skill and does not really tell you anything about steering characteristics. There are multiple people riding MBB bikes effortlessly no hands (I cannot), there are videos of people riding 'conventional' SWB bents with tiller and even lowracers no-hands (most people cannot, indeed), there are reports that some people (circus athletes, mostly) being able to ride early FWD-rear wheel steering bents that absolute most people find completely unrideable.
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Posted By: bob walton
Date Posted: 07 March 2018 at 5:06pm
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I thought you could see from the videos it was stable. Most people that tried it, learnt how to ride it in about 2 seconds. If you don't believe me, I don't care. ------------- funnyfrontend |
Posted By: Balor
Date Posted: 09 March 2018 at 10:21am
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Oh, I do trust you - like I said, I've tried a similar design, and it rides fine (and would ride even better with a functional remote). I just remind you that a video of riding no-hands does not actually prove anything conclusively :).
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