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Head tube angle, trail and tiller |
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GeoffBird
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Joined: 20 September 2005 Status: Offline Points: 2396 |
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Posted: 06 April 2015 at 2:07pm |
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Karl, I was going to say that my experience of building bikes is that about 80 degrees works really well, as long as you don't have much tiller. But I prefer a bit more trail for a touring machine (so a bit of negative offset) - makes for more relaxed handling when you're tired. I'd go for the steepest head angle you can (up to about 80 degrees) for no more than 7 or 8 inches of tiller.
A vertical head angle gives incredible low speed (walking pace) stability, but conscious movement of the steering to get it to turn into a corner, in contrast to many Dutch recumbents, with fairly relaxed head angles and little trail, which I find twitchy in a straight line and having a tendency to fall into corners in a rather unnerving way, but maybe it's just what I'm used to. All this is rather unscientific as it is difficult to change only one parameter affecting steering feel at a time, even if I'd tried to. All I can say in defence of my argument is that most people find most the bikes I build easy to ride, with the possible exception of the high racer I built last century which had a conventional head angle and offset, so not much trail
Edited by GeoffBird - 06 April 2015 at 10:19pm |
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Right Time - Right Place - Wrong Speed
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garryb59
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Joined: 28 May 2005 Location: United Kingdom Status: Offline Points: 243 |
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Posted: 06 April 2015 at 9:16pm |
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I was going to mention tiller. I'm always conscious of trying to balance all these things out, so neither tiller, trail or HTA are too extreme, but the situation is being made more difficult by having handlebars really quite close to my body. However, sitting on the bike stationary and just imagining where my hands would like to be if I were to start afresh, indicates a more forward position, which would cut down the need for quite so much tiller and thus facilitate a steeper head tube angle. That will be the next job, to look more closely at the ergonomics of the handlebar position.
Thanks for the feedback Geoff, really appreciate it. Edited by garryb59 - 06 April 2015 at 9:31pm |
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GeoffBird
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Joined: 20 September 2005 Status: Offline Points: 2396 |
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Posted: 06 April 2015 at 10:14pm |
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Your design looks a good compromise to me Gary. You've built a few bikes - does your experience tally with mine? Has anyone else who has built and/or ridden quite a few different bikes got an opinion?
Edited by GeoffBird - 06 April 2015 at 10:19pm |
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Right Time - Right Place - Wrong Speed
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legs_larry
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Joined: 09 March 2005 Location: London Town Devine Status: Offline Points: 1554 |
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Posted: 07 April 2015 at 9:04am |
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Having had the pleasure of Garry's company on numerous rides back in the last decade I can assure Thee Panel that after ~1100 km he had far more spare grey matter than I did.
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a bit ov a lyv wyr by slof standirds |
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garryb59
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Joined: 28 May 2005 Location: United Kingdom Status: Offline Points: 243 |
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Posted: 07 April 2015 at 10:09pm |
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Tell you what Dave - I'm still dithering, I might be there, I might not, but I can honestly say that if I do make it to the start line in Paris in August, I will be parked among the dark side fraternity, waiting for the off, and your presence will be greatly missed. Really. You are not the reason I ride recumbents, but you are the reason I ride recumbents on Audax. [BTW, can you give me your home address, so I can send my private psychiatric bill that bears testimony to the fact :-) |
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garryb59
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Joined: 28 May 2005 Location: United Kingdom Status: Offline Points: 243 |
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Posted: 07 April 2015 at 11:57pm |
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Well....problem is Geoff, I tend to come from a non-scientific background of 'not quite sure what I'm doing but I've heard that this is what needs to be done'...kind of thing. I have a decent practical aptitude, but do not possess a technical, scientific background, and let's face it, the two can obviously work well together. I've also definitely not built a bike with a HTA greater than 74dg, so your 'up to 80dg' answer is interesting, particularly when you talk about slow speed stability....and for me, that's very important! Looking at the tiller on this latest bike, It comes in at around 7". I'm not sure I'd want any more than that. Thing is: if you had two bikes, one with 80dg HTA, zero offset and 50mm of trail, and another with a HTA od 72dg, 30mm of off set and trail of 50mm would the handling charachteristics be the same? Now I rememebr the feeling - as soon as you've built one, you want to build another bike straight away !! As an aside - I've looked, but I think it's a no-goer, but is it possible in your experience to source 20g 1.3/4" - 45mm steel tubing, that would be MIGable? I've not seen anything like this that is commerically available. The best I can get is 18g 1.3/4". Second question - ever used a mandrel bender? Might they be ok for thin wall steel tubing? I'm constantly amazed how welding can make a length of steel tubing so much heavier. How does that happen? A few lap joints, bit of gusset support and it totally seems to change the weight character of a length of steel without seemingly adding much extra metal?? I've got that carbon fabric sitting here, but I still can't let go of the fact that it must be possible to build a steel bike for Audax that doesn't weigh a ton. Sure, it's not going to be light, I don't expect that....but just not quite so heavy as the 38lber that my latest offering is. Am I delusional? [Why do I even ask he question :-)] |
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