A BIKE THAT HANDLES PROPERLY. Define it; for general use

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slowster
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Re: A BIKE THAT HANDLES PROPERLY. Define it; for general use

Post by slowster »

Bmblbzzz wrote: 10 Jul 2024, 8:27am But the quote is comparing two bikes with the same trail and different "wheel flop", so different behaviour can't be down to trail.
The article asserts different behaviour at high speed, but gives no evidence or proof of it. I doubt that it is correct. I think if it were true that slacker head angles but with the same trail were significantly less stable at high speed, it is something which would be reasonably well known and commented on.

It is at low speed that differences in wheel flop - especially large amounts of wheel flop - are so noticeable by the rider. I suspect that the greater rotational inertia at high speed minimises the impact of a difference in wheel flop between two bikes with the same trail.
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Re: A BIKE THAT HANDLES PROPERLY. Define it; for general use

Post by Bmblbzzz »

Yes, that bit seems dubious, especially without defining high speed and explaining why speed xyz is where behaviour changes over. In fact, my only experiences of wheel flop have been when I attached front panniers to an MTB with suspension fork, which I put down to the high trail (I'm not saying that was definitely the reason, just my attribution at the time), and on a bike with bent forks (had clearly been run into something solid at some point – forks bent slightly back from the intended angle, so effectively less rake therefore more trail but still a "normal for road" head angle – the handling was both twitchy and floppy).
Brucey
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Re: A BIKE THAT HANDLES PROPERLY. Define it; for general use

Post by Brucey »

slowster wrote:....It is at low speed that differences in wheel flop - especially large amounts of wheel flop - are so noticeable by the rider. I suspect that the greater rotational inertia at high speed minimises the impact of a difference in wheel flop between two bikes with the same trail.......
FWIW I more or less agree.
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Re: A BIKE THAT HANDLES PROPERLY. Define it; for general use

Post by jimlews »

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Re: A BIKE THAT HANDLES PROPERLY. Define it; for general use

Post by mig »

what movement initiates steering? is it always the same?
slowster
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Re: A BIKE THAT HANDLES PROPERLY. Define it; for general use

Post by slowster »

The two blog articles by Dave Moulton linked below are interesting, especially the second in the context of this thread, not least because he was building frames during/shortly after a period when framebuilders were having to adjust the geometries they typically used because of changing road conditions. He describes how framebuilders moved away from zero trail/no wheel flop steering, and the criteria that led him to build with even more trail than many other framebuilders. He arrived at his preferences and understanding by an empirical trial and error process, rather than 'received wisdom', which can be very wrong when it involves a very complex and sometimes counter-intuitive subject like bicycle steering and geometry.

http://davesbikeblog.squarespace.com/bl ... story.html

http://davesbikeblog.squarespace.com/bl ... cycle.html

Regarding the issue of how a bike rides no-handed, one of his replies to a comment is:
I always designed and built bikes to go around corners fast. Riding "No hands" was never a consideration.
In the article itself, he says:
In time I found there was an “Optimum Handling” line that I could draw on my graph, that would show me the fork rake needed for a given head angle...

... my standard road geometry gave this same ability to lean into a corner, let the bike take you round, but if you needed to correct your line, or steer around an obstruction, you can physically steer the bike by turning the bars, and pointing the bike in the direction you need to go.

I have said before, my bikes had a little more trail than most others built back when I was building, and more than on bikes produced today. That is not to say I am right, and all others are wrong, it is just my design philosophy is different.

The handling qualities of a bike do not depend on the steering geometry alone, it is the design of the whole frame, weight distribution, etc., etc.

When I recently rode a carbon-fiber framed bike, it felt okay, but the steering was different. Not bad, nothing I could put my finger on, or nothing that I could not get used to, given time.
Dave Moulton's 'optimum handling' in his chart below corresponds to trail in the high 60s. I am not a particularly good bike handler and I am not a confident descender, but the comment about being able to lean steer and also be able to make corrections is something I recognise in how a touring bike (a Spa Tourer) with similar 64mm trail behaves when cornering.

Image

Most pros now probably ride off the peg frames, which presumably all have similar trail and handling, and I doubt there is the scope for a pro to have a frame with Dave Moulton's 'optimum trail'.
Manc33
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Re: A BIKE THAT HANDLES PROPERLY. Define it; for general use

Post by Manc33 »

I'd define handling properly as having the most stability - flat wide handlebars and a bottom bracket that's as low as it can be without pedals hitting the ground. I noticed going from road to MTB that sitting higher up (even by a few inches) has quite an effect and you can't balance as well on the MTB, but the wider handlebars supposedly makes it all equal out.

In that case I guess a road frame with flat handlebars and maybe even a stem a bit longer than usual MTB, could make it the most stable. Never tried it!
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Re: A BIKE THAT HANDLES PROPERLY. Define it; for general use

Post by Nearholmer »

^^^

Like this, maybe?

IMG_0912.jpeg

It’s a combo that works for some things, but I’d say not for others.

Definitely very stable, definitely good when carrying a fair load, good on very lumpy ground because there’s the leverage to keep the front wheel from getting shoved off-line. You run out of gears going up steep hills a bit quicker than on drops, have to be a bit careful not to lift the front on very steep climbs, and it’s not huge fun into a strong headwind. Took me a while to get steering technique at any speed, which involves pushing the bar down, more than turning it.

(Putting a longer stem and simply wide flats, no sweep-back, is the old 1990s hybrid arrangement, and I don’t like it much. It’s stable, but tends to make my arms and shoulders ache by throwing too much weight too far forward.)
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Re: A BIKE THAT HANDLES PROPERLY. Define it; for general use

Post by pjclinch »

Manc33 wrote: 10 Jul 2024, 12:47pm I'd define handling properly as having the most stability - flat wide handlebars and a bottom bracket that's as low as it can be without pedals hitting the ground. I noticed going from road to MTB that sitting higher up (even by a few inches) has quite an effect and you can't balance as well on the MTB, but the wider handlebars supposedly makes it all equal out.
I wonder if this is at cross purposes to other uses of "stability" in this thread? Up until now it's mainly been about directional stability without active steering input, and I wouldn't have though BB height on its own or indeed handlebar type ought to affect that.

In terms of how easy it is to balance a bike, how fast one is going is a factor. The lowest bikes going are low-racer recumbents, and assuming they've been implemented reasonably these are no problem to balance at high speed while at walking pace they're very awkward. Penny-Farthings are apparently relatively easy to balance at very low speed compared to "normal" bikes.

I wonder if it was a change from what you were used to, rather than simply being higher, is what made an MTB seem harder to balance?

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Re: A BIKE THAT HANDLES PROPERLY. Define it; for general use

Post by cycle tramp »

pjclinch wrote: 10 Jul 2024, 1:35pm
Manc33 wrote: 10 Jul 2024, 12:47pm I'd define handling properly as having the most stability - flat wide handlebars and a bottom bracket that's as low as it can be without pedals hitting the ground. I noticed going from road to MTB that sitting higher up (even by a few inches) has quite an effect and you can't balance as well on the MTB, but the wider handlebars supposedly makes it all equal out.
I wonder if this is at cross purposes to other uses of "stability" in this thread? Up until now it's mainly been about directional stability without active steering input, and I wouldn't have though BB height on its own or indeed handlebar type ought to affect that.

Pete.
I'll agree with you that it shouldn't affect stability or even handling but it may affect the 'perception' of stability... if I added another 4 inches to your handlebars height, the steering on your bike would feel vague and distant, equally if I dropped your existing handlebar height by the same (on the misplaced assumption I could do so) then the steering would feel alot more direct...(even though your neck, shoulders, back and wrists might be screaming in agony)
I've done nothing to the bike itself except change one factor...

..so when we speak about bike handling, it's encompassing many factors, frame angles, materials, frame designs, tyre widths and type, saddles, handlebars and even how the bike fits the person.
Last edited by cycle tramp on 10 Jul 2024, 6:49pm, edited 2 times in total.
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Re: A BIKE THAT HANDLES PROPERLY. Define it; for general use

Post by Bmblbzzz »

You'd have changed the weight distribution too, which affects the steering.
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Re: A BIKE THAT HANDLES PROPERLY. Define it; for general use

Post by pjclinch »

cycle tramp wrote: 10 Jul 2024, 5:44pm
pjclinch wrote: 10 Jul 2024, 1:35pm
Manc33 wrote: 10 Jul 2024, 12:47pm I'd define handling properly as having the most stability - flat wide handlebars and a bottom bracket that's as low as it can be without pedals hitting the ground. I noticed going from road to MTB that sitting higher up (even by a few inches) has quite an effect and you can't balance as well on the MTB, but the wider handlebars supposedly makes it all equal out.
I wonder if this is at cross purposes to other uses of "stability" in this thread? Up until now it's mainly been about directional stability without active steering input, and I wouldn't have though BB height on its own or indeed handlebar type ought to affect that.
I'll agree with you that it shouldn't affect stability or even handling but it may affect the 'perception' of stability... if I added another 4 inches to your handlebars height, the steering on your bike would feel vague and distant, equally if I dropped your existing handlebar height by the same (on the misplaced assumption I could do so) then the steering would feel alot more direct...(even though your neck, shoulders, back and wrists might be screaming in agony)
I've done nothing to the bike itself except change on factor...

..so when we speak about bike handling, it's encompassing many factors, frame angles, materials, frame designs, tyre widths and type, saddles, handlebars and even how the bike fits the person.
Yes, I agree with all of that, which is quite a bit of why I think "proper handling" is about the total bike package, the rider and how they interact.

My recurring example of bar changing is switching between tiller bars and aero bars on an otherwise identical recumbent. The aero bars are fine, the tillers I just can't get happy with at all. Rock solid to twitchy by doing something with no effect on the bike's geometry, just the way I interact with it.
As it happens I've just changed the bars on my usual ride, going from flats on a short stem to North Roads on a long/steep one so they've gone up and back several inches, but though it's different it's not affected things as much as I'd thought it might. It does confirm I like sitting up straighter as I get older though!

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Re: A BIKE THAT HANDLES PROPERLY. Define it; for general use

Post by Brucey »

I think that my 'ideal handing line' would lie to the left of Mr Moulton's. It might not be straight, either.
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slowster
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Re: A BIKE THAT HANDLES PROPERLY. Define it; for general use

Post by slowster »

Brucey wrote: 11 Jul 2024, 11:07am I think that my 'ideal handing line' would lie to the left of Mr Moulton's. It might not be straight, either.
Would it be different depending on the circumstances? e.g. tarmac vs. roughstuff, flat/rolling countryside vs., say, North Wales or the Yorkshire Dales, unladen vs. heavily laden?
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Re: A BIKE THAT HANDLES PROPERLY. Define it; for general use

Post by Cyclothesist »

531colin wrote: 8 Jul 2024, 2:01pm As the title; define “PROPER HANDLING”……. for a bike for general use, not for massed start racing, or mountain bike parks, or bike obsessives who practice wheelies or riding no hands, but for ordinary folk with ordinary reflexes who just want a bike to ride, maybe to work, maybe with the kids, maybe for a ride at the weekend.
Well 531colin, this one is having a good run. I'm completely out of popcorn and Pepsi! 👏👏👏
It's a lot more good natured than the helmet threads too 😂
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