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Why not cogs outside of drops?

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Why not cogs outside of drops?

Old 05-14-24, 11:58 PM
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Originally Posted by prj71
I'd prefer that the crank arms be mounted to the handlebar stem with a chain going to the front wheel.
You just described a Rokon 2WD motorcycle.
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Old 05-15-24, 12:05 AM
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Originally Posted by prj71
Why can't I have a handlebar on the back of my seat?
I have a LWB USS 'bent (Long Wheelbase, Under Seat Steering, recumbent), which is close.

Oh, and it also has rear high monostays, so doesn't need an outboard cog, it could mount a belt drive with no problems. A really long belt drive, it uses about 2 chains in length. Haven't used it since moving away from flatland almost 25 years ago.
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Old 05-15-24, 08:43 AM
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I think I remember an old TT bike with the hbars under the headtube...
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Old 05-15-24, 02:40 PM
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Originally Posted by Duragrouch
Because then, instead of the hub rotating around a fixed axle, the axle has to rotate, which makes for a trickier dropout to support a bearing for that, which describes a typical "semi-floating" car or truck axle. Or, a fixed axle that is hollow and the driveshaft fits through it and transmits torque only, does not take bending loads; I just described a "full floating" truck axle. It can be done, just at greater cost.
interesting, thank you!
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Old 05-15-24, 02:43 PM
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Originally Posted by wheelreason
And what is the plan for transferring the torque from the cog(s) to the hub body?
an axel that connects to the hub? Again, I am asking for information, which I have gotten some answers to. Essentially it is doable but not worth the extra complications.
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Old 05-15-24, 02:45 PM
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Originally Posted by prj71
Why can't I have a handlebar on the back of my seat?
I don’t understand?
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Old 05-16-24, 07:25 AM
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Originally Posted by prj71
Why can't I have a handlebar on the back of my seat?
Who told you you couldn't?

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Old 05-16-24, 07:31 AM
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I thought that this was a zombie January snow day thread
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Old 05-16-24, 12:45 PM
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Originally Posted by wheelreason
I think I remember an old TT bike with the hbars under the headtube...
Many, the handlebar was attached to the fork crown.
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Old 05-16-24, 10:31 PM
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Originally Posted by tcs
Who told you you couldn't?

I've never seen that. Thought-provoking; His seat is too low, based on very bent leg on low pedal, but if seat goes up, steering needs to as well. With significant braking on front wheel, I think unstable, will stand on its nose, but with rider far aft over rear wheel, only rear braking may be needed. I don't think it folds, but if it did, that would be one compact folder. The achilles heel is hitting a pothole with that tiny front wheel and high CG to wheelbase, it would most certainly launch the rider forward. But darned interesting design nonetheless.
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Old 05-17-24, 06:41 AM
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Originally Posted by icedmocha
an axel that connects to the hub?.
Yeah, but the hub spins, and the axle is locked to the drop out, so assuming one would want to do this (can't imagine why) one would need some sort of hollow axle/driveshaft contraption thing.
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Old 05-17-24, 11:21 AM
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Originally Posted by RH Clark
It should be much easier to make a carbon belt that easily comes apart and back together without compromise.
You don't even have to do that if you really don't want to.

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Old 05-17-24, 10:33 PM
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Originally Posted by urbanknight
You don't even have to do that if you really don't want to.

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That front frame is basically a Helix, or vice-versa. What brand, model, and year if known? Unless Manitou is the bike and not just the fork.

Last edited by Duragrouch; 05-17-24 at 10:42 PM.
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Old 05-17-24, 11:59 PM
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Originally Posted by Duragrouch
That front frame is basically a Helix, or vice-versa. What brand, model, and year if known? Unless Manitou is the bike and not just the fork.
I have no idea. Just did a search for a frame with raised chainstays to make my point, and this was the first clean pic I found. There were a handful of manufacturers who made this type of frame back in the 90's (and probably other eras as well), and I just remember there being an advantage to not having to break the chain to remove and clean it, and not getting any chain slap on the frame.
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Old 05-18-24, 05:09 AM
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The arching-cantilever folding bike frame, pioneered by Dahon and widely copied.



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Old 05-18-24, 07:08 AM
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Originally Posted by Duragrouch
That front frame is basically a Helix, or vice-versa. What brand, model, and year if known? Unless Manitou is the bike and not just the fork.

Sorta looks like a Nishiki(?) Alien. Elevated chainstays made by several companies IIRC

https://www.bikeforums.net/classic-vintage/1293765-head-branded-elevated-chainstay-bike.html

https://www.mtbr.com/threads/1993-nishiki-alien.347140/


Last edited by Steel Charlie; 05-18-24 at 07:29 AM.
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Old 05-18-24, 02:07 PM
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Originally Posted by tcs
The arching-cantilever folding bike frame, pioneered by Dahon and widely copied.



There's no question, belt-drive is the killer app for that frame style. I'm just surprised that style is so widely used in the Dahon line, and not just one model for belts; 99% of the ones sold in that style will never see belts, and it's a less efficient design structurally (so heavier) than a triangulated rear, especially in aluminum, to keep those cantilevers from breaking in fatigue (on the bottoms of them, in tension). Now if it could be made of a strong enough steel to let them flex vertically, that's a nice suspension, but even in steel, that's really hard to keep from fatiguing. I do know of a titanium mountain bike with a very simple, low travel rear suspension, the seatstay monostay upper has a short spring of some kind, and the chainstays flex in bending. But if parts for belt-drive and a good internal hub come down in price, there's a plethora of Dahon Mu bikes on the market for conversions. But I still wouldn't put tour weight on it. Dahon is triangulating the front triangles with their Deltec cable design, but that doesn't help the rear.

In recent years I've seen triangulated rear frames with bolt-on dropouts, I think that is the wave of the future; Structurally efficient, belt-capable, and can easily change between vertical and horizontal dropouts if desired, and the same for quick-release and thru-axles.

Last edited by Duragrouch; 05-18-24 at 02:15 PM.
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Old 05-18-24, 02:42 PM
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In the motorcycle world, Honda developed single-sides rear swingarms for endurance racing where the rear wheel could be swapped out while the drivetrain (front cog, chain, rear cog) remained intact to speed up pit stops.


SOURCE: https://www.bikesales.com.au/editori...design-111773/

I could see the benefits of such a system in bicycle racing, making it faster to change a rear flat tire in the middle of a race. There is a weight penalty though and that's probably why it hasn't really been tried.
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Old 05-18-24, 04:58 PM
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Originally Posted by john m flores
In the motorcycle world, Honda developed single-sides rear swingarms for endurance racing where the rear wheel could be swapped out while the drivetrain (front cog, chain, rear cog) remained intact to speed up pit stops.


SOURCE: https://www.bikesales.com.au/editori...design-111773/

I could see the benefits of such a system in bicycle racing, making it faster to change a rear flat tire in the middle of a race. There is a weight penalty though and that's probably why it hasn't really been tried.
My guess is the Honda RC30 and subsequent VFR.

I think BMW may have been first on that, not certain, in concert with their shaft drive on the right side. VFRs had single-sided swing arm and chain drive on left side, as well as some Ducattis.

The Giant HalfWay folding bike I saw in the early 00s blew me away, being single-sided both front and rear, easy flat fixes in the field. I almost bought one, but test rode it and it was in hill country, gearing was not wide enough. So was my Dahon folder, but I was able to retrofit it, unlike the Halfway which would have been difficult or impossible to fit my 2X crank and front and rear racks as I have on my Dahon frame, and who knows if the hubs or at least the axle was special, or if just a standard high-grade bolt.

EDIT: Looking at link now, yep, RC30. SS swingarm was the least of its radicalness, IIRC, a 90 degree V-4 with 4 "oval" pistons (flat thrust sides with radiused ends) with 2 connecting rods each, and each allowing 8 valves per cylinder, 4 intake, 4 exhaust.

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Old 05-20-24, 06:04 AM
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Originally Posted by Duragrouch
My guess is the Honda RC30 and subsequent VFR.

I think BMW may have been first on that, not certain, in concert with their shaft drive on the right side. VFRs had single-sided swing arm and chain drive on left side, as well as some Ducattis.

The Giant HalfWay folding bike I saw in the early 00s blew me away, being single-sided both front and rear, easy flat fixes in the field. I almost bought one, but test rode it and it was in hill country, gearing was not wide enough. So was my Dahon folder, but I was able to retrofit it, unlike the Halfway which would have been difficult or impossible to fit my 2X crank and front and rear racks as I have on my Dahon frame, and who knows if the hubs or at least the axle was special, or if just a standard high-grade bolt.

EDIT: Looking at link now, yep, RC30. SS swingarm was the least of its radicalness, IIRC, a 90 degree V-4 with 4 "oval" pistons (flat thrust sides with radiused ends) with 2 connecting rods each, and each allowing 8 valves per cylinder, 4 intake, 4 exhaust.
Wow that HalfWay looks pretty cool. I wonder what kind of weight penalty, if any, there was for the single sided fork and rear end?

The oval-pistoned Hondas were the NR race bikes; the RC30 was still pretty trick as a V-4 though.

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Old 05-20-24, 07:28 AM
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Originally Posted by john m flores
Wow that HalfWay looks pretty cool. I wonder what kind of weight penalty, if any, there was for the single sided fork and rear end?

The oval-pistoned Hondas were the NR race bikes; the RC30 was still pretty trick as a V-4 though.
That Halfway did look cool. But try to mount front and rear racks on single-sided forks. A better view than you may have seen:

I think that may be one of those designs where the issue was not as much stress, but stiffness from axle deflection under all vertical, braking, and thrust loads. And being aluminum structure, it needed to be stiff to resist fatigue.

For me, the '98(?) and on VFR800 was plenty cool, that would have been my choice if I ever bought a motorbike. Perhaps 4 or 5 years back, local they had the next model with ABS and underseat exhaust, used, low miles, mint, and the special red/white/blue paint scheme, I think an anniversary edition, pretty cheap. But I've got nowhere to store it off the street. Also saw cheap BMW K1300S, like 175 hp stock, although a lot of that is lost as the transverse 4 with shaft drive, required 2 90-degree gearsets to send power aft, so a lot lost that way. The suspension was as good as it gets, tele or paralever rear (multilink with anti-lift and anti-squat), and in place of their normal excellent front fork which is actually a longitudinal oriented MacPherson strut, on the K they used a longitudinally oriented multilink SLA (Hock-something-or other?), fabulous anti-dive; Mint condition and like 15k miles, $6k, tremendous deal, had to pass. I also don't need a 1300cc bike, though it weighed about the same as the VFR800.
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Old 05-20-24, 10:31 AM
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Originally Posted by john m flores
In the motorcycle world, Honda developed single-sides rear swingarms for endurance racing...
Vespa. Front and rear single-sided wheels since 1946. Most models even carried a spare tire.



In the bicycle world, prolly most successful single-sided design is Strida: every Strida since 1986 has been single-sided F/R (but with the cog 'inside' the frame).


Last edited by tcs; 05-20-24 at 10:41 AM.
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Old 05-20-24, 09:33 PM
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(above) I did not know either! Thanks!
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Old 05-21-24, 10:53 AM
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Originally Posted by Duragrouch
Dahon is triangulating the front triangles with their Deltec cable design, but that doesn't help the rear.
Dr. Hon has gotten on a real triangulation kick lately.




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Old 05-21-24, 03:31 PM
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I been toying with this same idea since seeing a BMW motorbike a few weeks ago with a single sided swing arm and wondered if bikes could do the same. One advantage is the wheel could become very "dumb" like a car wheel which has no moving parts and presuming you have disc brakes, the disc remains attached to a hub on the swingarm. One issue I see is the cassette (assuming multi geared) would be protruding from the swingarm and be unprotected in a crash and liable to snap off or do major damage. I suppose this could be mitigated by a bash guard.
The rear derailleur would also need a total redesign as it would attach to the swingarm and swing "out" from big to little cog but geometry wise this is easier than current method of swinging "in".
But agreed that even if these advantages add up to a slightly simpler design with easier wheel changes, maintenance and perhaps lower part count, the gains are marginal for the R&D required and the tooling costs and the prospect of convincing bike customers who are pretty conservative with what they expect a bike to look like, the ask is too much.
Still, it raises an interesting question as to whether the fundamentals of bike design could be radically improved especially with the advent of disc brakes, electronic shifting and advanced materials.
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