What keeps some promising new bike technologies/designs from being accepted?

[Tobias]

In the custom 11 thread shiftyfixedgear mentioned that Shimano had used a 10 mm chain pitch in the past. Having wondered myself why the ½-inch pitch was still in use when most manufacturing has gone metric, I did a little research out of curiosity.

It appears that there were technical advantages (including the ever-important lower weight) but it wasn’t accepted as a new standard. But why?

Was the US unwilling to accept a metric conversion in 1976? Did the industry resist it as a solution to a problem that didn’t exist? Was there a little “not invented by Americans” arrogance involved? Those were the days when Japanese products were still considered inferior, right? Was retooling manufacturing cost prohibitive? Maybe we just needed stimulus funding to subsidize retooling capital. :rolleyes:

Beyond the claimed potential for lower weight other advantages were either not addressed effectively or ignored completely. So we stuck with ½-inch pitch chains even though over time they were not interchangeable anyway.

My question is whether this was a case where free markets didn’t work for us, or was the new-and-improved Shimano 10-mm-pitch drivetrain not successful because it really wasn’t new-enough or improved-enough to justify the higher costs, or inconvenience of change, or whatever? Was it too much “bike” racing regulation that killed it? Maybe free markets did exactly what they should and weeded out a bad idea. What do you think?

I’d like to hear your ideas on this and other potentially promising bike ideas that didn’t take off and your thoughts as to why. There must be many examples out there.

[AndrewS]

Take a look at Shimano's AX series of aero and ergonomic changes to the way parts are put together.

Shimano sold these groups with a non-standard oversized pedal shaft to lower the foot closer to the pedals axis. Was it a good idea? Maybe. Was it worth a major change in one of the standards that make bike parts interchangeable? Definitely not.

I don't know if there were major advantages to making the links 2mm shorter on a chain. But it's a major obstacle to producing a part if you want everyone to throw out their entire drivetrain to even try it.

Indexing, STI, aheadsets, clipless pedals, composite frames, aero brake levers, double pivot brakes, etc are all easily retrofittable to the bikes current at the time of introduction. I'm surprised when I see Specialized using special bosses for new "aero" calipers on TT bikes because that sort of thing always causes problems.

The benefit to a complete change in standard has to be huge enough to drop the old standard and not be obliterated by someone else's new standard. If Shimano had successfully debuted 10mm chains, they still ran the enormous risk that Suntour might have crushed them with a 9mm format, like VHS and Beta or HD vs. Blu Ray. It is much safer to work within certain constraints and not stick your neck out too far until you have a clear advantage.

That's the reason that we have been using brifters for 20 years but still base them around friction rear derailleurs.

[palincss]

That's the reason that we have been using brifters for 20 years but still base them around friction rear derailleurs.

Shimano tried rear derailleurs with the indexing in the derailleur first.
http://www.sheldonbrown.com/shimano.html#positron

[goonster]

That's the reason that we have been using brifters for 20 years but still base them around friction rear derailleurs.
The Shimano folks feel strongly that riders prefer to feel the shift in the shifter. If the indexing is in the rear der, there is less feedback to the rider.

I think the industry is almost entirely marketing-driven. People will pay $700 for a set of boutique cranks, but nobody wants to change to non-standard rings, cassette, der pulleys, etc. for a marginally "better" chain.

[AndrewS]

I remember. Hecklers were yelling "Positron!" at the trade shows when Shimano was attempting to introduce SIS. It didn't work well, was still based on a sprung derailleur and was at a quality/price point level intended for department store bikes.

[fiamme red]

10mm pitch was marketed to track cyclists, who are very conservative and tend to stick with old equipment that they have always relied on. Besides, the Japanese keirin federation didn't approve of it.

Here's the page from the Shimano 1982 catalog: http://sheldonbrown.com/shimano1982/pages/11.html

[AndrewS]

The Shimano folks feel strongly that riders prefer to feel the shift in the shifter. Just curious, where'd you hear that? It didn't stop them from introducing electric shifting.

[Tobias]

I don't know if there were major advantages to making the links 2mm shorter on a chain. But it's a major obstacle to producing a part if you want everyone to throw out their entire drivetrain to even try it.


It's a good point, but how different is it than buying an all new group? How many parts on Campy 11 speed are suppose to interchange with 10 speed, or more so with 9-speed, and even if they can be made to work by mixing them up, how many of them are actually sold that way? My guess is that the vast majority of Campy 11 speed or any new group for that matter is sold as a complete set, either through a bike OEM or to the buyer/user. Isn't that why they call it a "group"? ;)

[goonster]

Just curious, where'd you hear that? It didn't stop them from introducing electric shifting.
Kozo Shimano said that in a Riv Reader interview.

It is a valid engineering decision. Sometimes you have to choose between the machine that works best, and the machine that the people who use it want.

Grant P was pushing for indexed derailers, since that would allow him to use friction shifters will all drivetrains. The downside, of course, would be a loss of forward compatibility to newer indexing standards.

[AndrewS]

The number of 4 or 6 piece "mini groups" sold on the net that upgrade the minimum number of items leads me to believe that the group argument doesn't amount to much.

That trend, BTW, started around 1987 when Shimano sold kits containing shifters, RD and freewheels that allowed you to upgrade to SIS. Suntour, Sachs, Campy and Suntour all followed suit.

The whole idea of the inviolable "group" really comes from Shimano's trade practices of the late '80s and early '90s, which they were sued for.

I much admire Shimano learning it's lesson a long time ago so we can use 9 and 10 cogs on freehubs intended for 8.

[AndrewS]

Leave it to Grant to wish for an innovation so you could continue to do something backwards. Friction levers are silly. The current standard at least allows you to turn a barcon to friction if you want to. And do it from the saddle.

If we went to indexed derailleurs, it would be to use a completely new kind of shifter that is easier to use than a brifter or friction lever.

[goonster]

Friction levers are silly.
Well, that's just, like, your opinion, man. :rolleyes:

The current standard at least allows you to turn a barcon to friction if you want to.
The current Shimano standard is inferior to proper retrofriction/microratchet mechanisms.

If we went to indexed derailleurs, it would be to use a completely new kind of shifter that is easier to use than a brifter or friction lever.
What kind of "completely new" shifter did you have in mind?

I believe there have been indexed derailers before, but can't recall if they were pioneered by Suntour or a French company . . .

[AndrewS]

The convenience of electric shifting but mechanical with one cable. Multiple shifter locations and push buttons.

You know, I have Simplex retrofriction on one bike. It "feels" nicer but it doesn't seem to make me shift any better.

My point with the lever thing was simply that an index derailleur will work with either kind of shifter, and index shifters can work as friction. But an index derailleur, even if you could get it to work well with a friction lever (which I doubt) would not allow for on the fly switching back to friction. It makes more sense to put a dual mechanism up by the rider than back by the RD.

And if you're just talking about permanent indexing rather than a friction option, why would you care how the shifter feels?


I suppose if someone really wanted to they could make a shifter that switches between index and retrofriction. I have a Sachs shifter that goes from index 8 to microindex (like gripshift friction front shifters). That would have really set the world on fire in 1991.

[goonster]

And if you're just talking about permanent indexing rather than a friction option, why would you care how the shifter feels?
Every single gruppo review everywhere talks about how the shifts feel. Campy is "crisper", DuraAce is "smoother", that one is "more responsive", this one is "satisfyingly positive", et cetera ad nauseam . . .

In the absence of any objective performance criteria for any of this stuff, feel is all there is!

[AndrewS]

Specifically, what "feel" advantage would there be by using the precision of retrofriction with the large bumps of an index derailleur.

The click feel is the reason Shimano was against this. What sort of "feel" are you going to get from the greatest friction shifter if huge clunks are feeding back through the cable from the FD? Those clunks are going to be the only thing that you'll notice.

[goonster]

Specifically, what "feel" advantage would there be by using the precision of retrofriction with the large bumps of an index derailleur.

I don't know what it feels like, but don't presume an advantage in "feel". I'm not advocating this. I like friction shifters with friction derailers (for several reasons, and not necessarily because it is the "best" configuration).

The click feel is the reason Shimano was against this. What sort of "feel" are you going to get from the greatest friction shifter if huge clunks are feeding back through the cable from the FD?
No, with an indexed derailer the clicks would be isolated from the shifter. Shimano likes the indexing in the shifter because there is "more click" or "better click" in terms of feedback to the rider.

[RPS]

I think in the absence of excessive and/or unfair regulations markets usually get it right, although potential long-term advantages can sometimes be stifled by short-term costs or risk adversity.

http://autobus.cyclingnews.com/tech.php?id=tech/2005/news/01-04

In this case '10' doesn't signify ten gears, but 10mm - the pitch of the chain in this scaled-down design. Almost all bike chains are half-inch pitch, so the centres of the pins are half an inch, or 12.7mm, apart. Introduced in 1976, and discontinued some time in the 80s, Dura-Ace 10 used a smaller chain and therefore smaller chainrings and sprockets - the number of teeth was the same, but they were closer together. The big advantage was lower weight, and eventually, according to legend, the Japanese kierin federation banned the 10mm pitch equipment because it might give some riders an unfair advantage.
Same number of teeth leads to smaller sprocket diameters and therefore higher chain tensions. Shimano apparently wasn’t too concerned about that. The flip side to this argument would be that back in 1976 smaller sprockets were not in use as they are today. Sprocket sizes got smaller anyway but by reducing the number of teeth rather than the chain pitch. Maybe that in part mitigated the need for the new 10-mm chain.

In researching this I found it interesting that most everyone thought the main advantage was weight savings. It seems Shimano didn’t promote other advantages; or maybe that's the only part anyone remembers. :rolleyes:

[AndrewS]

Goonster, I'm having a hard time figuring out what you and/or Grant are advocating. Current RDs ARE friction derailleurs and work with friction or index shifters.

What scenario would be better if an RD with indexing built into it were combined with a fine grade friction shifter?

You can't have an index RD that doesn't feed back to the shifter somehow. The clicks will either be felt or the RD will shift in seemingly arbitrary shifter positions. If the RD is moving precisely to index points but the shifter is only moved to approximations of those points, then you'll have unpredictable shifter movement for different shifts, which will just confuse the rider trying to guess how far to move the lever to influence the RD to shift. There has to be some sort of feedback or direct mechanical connection.

[AndrewS]

I wonder why increasing the number of link pins and bushings would have made anything much lighter?

The wear advantage with compact drivetrains doesn't seem like a bad idea, though. I don't think the chain tension goes up with smaller cogs, but the increased surface area with more teeth per a given circumfrance would help combat friction wear.I think in the absence of excessive and/or unfair regulations markets usually get it right, although potential long-term advantages can sometimes be stifled by short-term costs or risk adversity.


Same number of teeth leads to smaller sprocket diameters and therefore higher chain tensions. Shimano apparently wasn’t too concerned about that. The flip side to this argument would be that back in 1976 smaller sprockets were not in use as they are today. Sprocket sizes got smaller anyway but by reducing the number of teeth rather than the chain pitch. Maybe that in part mitigated the need for the new 10-mm chain.

In researching this I found it interesting that most everyone thought the main advantage was weight savings. It seems Shimano didn’t promote other advantages; or maybe that's the only part anyone remembers. :rolleyes:

[RPS]

I wonder why increasing the number of link pins and bushings would have made anything much lighter?

The wear advantage with compact drivetrains doesn't seem like a bad idea, though. I don't think the chain tension goes up with smaller cogs, but the increased surface area with more teeth per a given circumfrance would help combat friction wear.
Andrew, I thought the same about chain weight. However, they may have saved more on cassettes, derailleurs, and rings to make up for chain weight. I don't know if the chain was heavier, but it wouldn't surprise me if it was.

As to wear, you have it backwards. If they ran the same gears measured in number of teeth (lets say a 50-16 ratio) then the ring and cog would both be smaller in diameter. And in order to transfer the same amount of power at the same cadence, the chain would indeed have to be under greater tension.

Having stated that, I'd also have to say the chain would be traveling slower, hence each link would not come around as often. But typically wear is affected more by higher tension than lower speed. Overall I'd expect higher wear if the number of teeth was kept the same.

But that's where I don't get the same number of teeth assumption. They could have gone to the same pitch diameters by using more teeth per ring/cog.

[fiamme red]

Andrew, I thought the same about chain weight. However, they may have saved more on cassettes, derailleurs, and rings to make up for chain weight. I don't know if the chain was heavier, but it wouldn't surprise me if it was.Dura Ace 10mm pitch components were never produced for multispeed bikes (or at least never sold on the market).

I know someone who used Dura Ace 10mm on a track bike, and he said that it was noisier than 1/2".

[RPS]

I’d like to hear your ideas on this and other potentially promising bike ideas that didn’t take off and your thoughts as to why. There must be many examples out there.
One that comes to mind is partially self-actuated brakes to reduce effort. Reports of riders inadvertently locking them up probably kept them from becoming popular, although if the assist ratio was low I don’t see how they would be that much easier to lock up than standard brakes with too much leverage.

[fiamme red]

http://www.bikeforums.net/showthread.php?108413-Dura-Ace-10-Pitch-~-What-s-The-Freakin-Deal&p=1184315&viewfull=1#post1184315

[goonster]

I'm having a hard time figuring out what you and/or Grant are advocating.
I'm not advocating anything in this thread. My contribution here is to explain why Shimano has the indexing in the shifter instead of the derailer.

Grant preferred to have the indexing in the derailer, since that would expand the options for low-cost, simple shifters for bar-ends and upright handlebar shifters.

Another advantage Grant has mentioned (I think) is that with the indexing in the derailer the shift cable adjustment becomes less critical. You need enough travel to shift over the entire range, but a small change in cable length won't throw off every shift.

You can't have an index RD that doesn't feed back to the shifter somehow.
Yes, I know. My point here, again, is that there is less feedback to the rider if the indexing is in the derailer, since the click has to travel all the way up the cable. Shimano expressly wants to put the click in the shifter, not the derailer, since that is the tactile impulse the rider seeks.

[RPS]

I know someone who used Dura Ace 10mm on a track bike, and he said that it was noisier than 1/2".
So is it smoother, noisier, or both? :confused:

11.4 seems to say it was very smooth.

[fiamme red]

So is it smoother, noisier, or both? :confused:

11.4 seems to say it was very smooth.Maybe my friend used a bad batch of lube on the DA 10mm chain, I don't know. I'm just reporting what he said. ;)

[AndrewS]

RPS, I think we were justing looking at things differently. I said less wear per circumference, which is another way of saying "for a given diameter cog, the one with more teeth will distribute friction across a greater area, decreasing total wear". The same principle could be stated as "for a given number of equal size teeth, two cogs with the same number of teeth will wear the same regardless of diameter."

As long as the wheel is going the same MPH, neither system is turning faster. The same number of teeth per minute will result from a smaller cog/chain pitch as from the standard one.


Goonster, if that's all Grant and you meant, then I agree. But the shifter wouldn't be "friction". It wouldn't have any friction component at all. It would probably have a counter spring of some sort.

[Mikej]

the uci

[RPS]

RPS, I think we were justing looking at things differently. I said less wear per circumference, which is another way of saying "for a given diameter cog, the one with more teeth will distribute friction across a greater area, decreasing total wear". The same principle could be stated as "for a given number of equal size teeth, two cogs with the same number of teeth will wear the same regardless of diameter."

As long as the wheel is going the same MPH, neither system is turning faster. The same number of teeth per minute will result from a smaller cog/chain pitch as from the standard one.
Are you trying to teach me mechanical engineering? :)

If so, I'm sorry to say you are not doing a very good job. I would point out how you misread my comments by reading information I did not state, and then coming to conclusions that seem correct but in reality are not because you don't have enough knowledge in this area to know what you don't know.

Having said that, it's not my job to teach you or anyone else engineering; not that I would anyway unless asked. Besides, after seeing how you and Dave have interacted recently I wouldn't want a repeat under any circumstance.

[AndrewS]

Actually RPS, I'm interested. Not in arguing but in learning. That's why I post on and read forums. Don't worry about the Dave situation - he was needlessly insulting. I don't have any pride tied up in discussing how a bike works.

So, given the same number of teeth on a standard vs. 10mm systems, which would wear faster and why?

[AndrewS]

RPS, I thought more about your post and understand what you're saying. The smaller diameter cogs are going to have more tension transmitted through them because they are a smaller lever arm than a larger cog, but doing the same work. And the chain is slower because, while the teeth per time is the same, there's know more links in the chain to go through.

I do agree - it just sounds like 10mm pitch and small cogs would increase wear, but it would at least be better than smaller cogs with 1/2" pitch chain.

[RPS]

RPS, I thought more about your post and understand what you're saying. The smaller diameter cogs are going to have more tension transmitted through them because they are a smaller lever arm than a larger cog, but doing the same work. And the chain is slower because, while the teeth per time is the same, there's know more links in the chain to go through.Great: It's often better to figure things out on your own -- you'll remember the principle better. :beer:

I do agree - it just sounds like 10mm pitch and small cogs would increase wear, but it would at least be better than smaller cogs with 1/2" pitch chain.
Given the same pitch diameters of the chainrings or cogs I'm not sure it would make enough wear difference either way. Other factors would still be significant which is why we have different wear rates between different models of standard 1/2-inch pitch chains now.

One advantage I see to shorter chain pitch is that cassettes could be designed with slightly more even steps given similar physical sizes (i.e. -- cog diameters, not number of teeth).

I also don't get the assumption some made that the entire drivetrain would have to be replaced as a unit or all at once. What would keep Shimano or anyone from making chainrings with 10-mm pitch teeth that would bolt on the same crankarms? Or cassettes that slipped onto the same freehub? And why would index shifters care as long as cog spacing is the same?

And if the chain is the same width, I'm not sure the same front derailleur couldn't work, or the rear with minor modifications. In any case I do agree with the OP that about 30 years after Carter tried to get us to convert to the metric system -- with some success -- that it's odd bicycle chains are still 1/2-inch. If not 10 mm why not 12 or 13 mm or whatever makes most technical sense?

[AndrewS]

You're right - it should only take new chainrings, pulleys, cogs, chain and chain tools. Unless you're also going to a smaller cogs, then you might run into problems with FW body and crank BCD.

Pedal spindles are also Imperial in size and thread. I suppose we could just start calling the chains 12.7mm pitch, just like we call bar diameter 25.4mm. Happy birthday Mr. President...

[Tobias]

One that comes to mind is partially self-actuated brakes to reduce effort. Reports of riders inadvertently locking them up probably kept them from becoming popular, although if the assist ratio was low I don’t see how they would be that much easier to lock up than standard brakes with too much leverage.
By self actuated I assume it means self assisted, much like drum brakes, right?

I'd like to Google them. Who made them and how long ago. Anyone know?

[Tobias]

The lack of comments regarding designs other than mentioned in the OP makes it seem that very few "promising" ideas don't make it. Maybe markets do work quite well. We can probably think of plenty of bad ideas that didn't make it to the level of serious cyclists (like automatic shifting and other goofy ideas) that were not ready for prime time, or maybe they were just ahead of their time due to lack of other technologies to support them. In the case of auto shifting, the new electronic shifting from Shimano could now very easily have an "auto" setting to maintain near-constant cadence. On the other hand trying to do it with weights hanging off spokes isn't so clean.

[AndrewS]

Actually, the Browning D.A.D. (auto derailleur) was a mechanical, automatic shifting system that was completely contained in the rear derailleur. It didn't sell because cyclists really don't want to be told what cadence to ride. :)

There are plenty of stupid things - I recall a two wheel drive line of ATBs that worked off an enormous speedometer type cable.

One failed idea was Airmet tubing. Light steel that required post welding heat treament, but no builder had an oven large enough.

Other things had their day, but faded because they were not inline with the times. Campy derailleur design in the late 80s was a fascinating bunch of dead ends. They worked pretty well, but didn't index well. Same thing with the Delta brake. Slingshot ATBs were also a flash in the pan. They were fast, but not compatible with suspension. Suntour command shifters were a great alternative to STI, but Suntour was dying already when they came out. The one piece aerobar, especially the Scott 100k, was a superior concept to clip-ons and bullhorns, but they were overtaken by fashion following Lemond's 89 TDF win.

[Tobias]

There are plenty of stupid things - I recall a two wheel drive line of ATBs that worked off an enormous speedometer type cable.

One failed idea was Airmet tubing. Light steel that required post welding heat treament, but no builder had an oven large enough.
It is easy to see stupid ideas not making it. It's a little tougher to see why good ideas don't.

In the case of Airmet, wasn't the issue also about alignment? Post heat treatment would leave a misaligned frame that would be very hard to align cold. Another issue as with many high-strength steels is that if the builder uses less of the material to make the frame light it then becomes too flexible (actually mean to say lack stiffness which isn't the same), unless large diameter tubes with very thin walls are used. And then it becomes easy to dent.

[MattTuck]

It is easy to see stupid ideas not making it. It's a little tougher to see why good ideas don't.



Google Roger's 5 factors, they are the keys to innovation diffusion.


Relative advantage
Compatability
Simplicity
Trialability
observability

[AndrewS]

The alignment issue was probably a big factor as well with Airmet. The rest of the problems are still there, but have been dealt with pretty well by 853 and other high end tube sets. Airmet attempted to do the same things but did it the wrong way.

[palincss]

By self actuated I assume it means self assisted, much like drum brakes, right?

I'd like to Google them. Who made them and how long ago. Anyone know?

AASHTA:


Self-energizing Brakes
Self-energizing brakes use some of the braking force to provide a "power assist" to the brakes. The best-known self-energizing brake is the Scott-Peterson (Sun Tour)cantilever, which has a steep helical thread as its pivot, so that the forward force exerted by the rim against the pads helps cause the pads to press harder than they would from hand effort alone.

Self-energizing brakes are quite controversial, because they can have a non-linear response, which may lead to wheel lock-up.
--http://www.sheldonbrown.com/gloss_sa-o.html

[RPS]

From Sheldon Brown:

Self-Energizing Cantilevers

Because of the myth that conventional cantilevers aren't strong enough for tandem use, some people favor Self-Energizing cantilevers. These don't have a simple pivot, instead, each arm moves on a steep multi-start screw thread, so that as the shoe approaches the rim it also moves forward. When it rubs on the moving rim, the forward pull tends to increase the inward pressure, providing a "positive feedback."

This design can apply greater braking force for less finger force than a conventional cantilever, but it is difficult to modulate it. The original Scott Pedersen SE brakes were available either for front or rear use (opposite direction threadings), but when Sun Tour bought the design, their legal department vetoed the front version, so only the rear model was made by Sun Tour. I advise against the use of Self Energizing brakes, because they make it too easy to lock up the wheel.

Article on safety concerns when combined with different forks:

http://www.johnforester.com/Articles/BicycleEng/sebrake.htm

The Pedersen brakes seem to have a lot of friction built in which would make them difficult to modulate under the best of conditions. The fact that they didn't work well doesn't preclude another design from doing so. I'm not aware of any for bicycles but self-energizing brakes work in other applications.

[oldpotatoe]

[QUOTE=AndrewS]Actually, the Browning D.A.D. (auto derailleur) was a mechanical, automatic shifting system that was completely contained in the rear derailleur. It didn't sell because cyclists really don't want to be told what cadence to ride. :)

There are plenty of stupid things - I recall a two wheel drive line of ATBs that worked off an enormous speedometer type cable.

One failed idea was Airmet tubing. Light steel that required post welding heat treament, but no builder had an oven large enough.



Reynolds recommends heat treatment of 953 if tig welded, BTW-Waterford lugs it to not have that requirement.

Lots of dumb things that are successful..ceramic bearings come to mind, oversized, carbon handlebars, ceramic headsets,

[Tobias]

AASHTA:
Thanks for the information. I was able to look them up based on name and they do seem a little crazy. Not something I'd want to try.

In Googling I did not find any other manufacturers for self-energizing bike brakes. Either these were the most popular, most recent, or worked the best.

[Tobias]

Article on safety concerns when combined with different forks:

http://www.johnforester.com/Articles/BicycleEng/sebrake.htm


I can't follow the post angle concern to understand why it makes as much difference when combined with self-energizing. The angle difference between straight and curved fork blades is minor.

If it were that critical I'd expect an even bigger difference when a normal caliper is installed behind the fork in a TT aero position instead of in typical front position.

[AndrewS]

It sounds like the legs of the shock forks had a tendency to rotate toward the brakes since they were between the oncoming wheel and the fork. As they rotated they increased the pressure on the rim. Like a check valve in a vein.

A rear brake would do the opposite, if the stays had the ability to twist like shock fork legs do. The braking would torque the stays so the brake bosses would move away from the rim.

[RPS]

It sounds like the legs of the shock forks had a tendency to rotate toward the brakes since they were between the oncoming wheel and the fork. As they rotated they increased the pressure on the rim. Like a check valve in a vein.

A rear brake would do the opposite, if the stays had the ability to twist like shock fork legs do. The braking would torque the stays so the brake bosses would move away from the rim.
Flexing or twisting was not the issue reviewed as I read it. The following explains the theoretical differences based on two dissimilar fork geometries.

The particular RockShox suspension fork that was used has what looks like an economical and light design. Such forks must be straight to allow the telescoping action that provides the suspension action, but, like bicycle forks generally, the axle must be ahead of the steering axis to provide proper bike handling (rake is the technical name for the forward distance). In most such designs, this rake is provided by welding a plate on the front face of the fork, which plate has the slots for the front axle somewhat more than one inch in front of the fork blade. This particular RockShox design eliminated the additional plates on each side by slanting the fork blades relative to the steering column at the top of the fork, thus providing proper rake without the additional plates. However, like conventional forks, the studs for mounting the brake arms were welded perpendicularly to the blade, and therefore were tilted up relative to the normal position because the blade was tilted forward. This meant that the motion of the rim had a downward component relative to the brake-arm studs, and that therefore the braking force tened to drive the brake arms downward and together, thus multiplying the braking force. This self-energizing effect was small enough to be ignored when using conventional brakes, but when combined with a brake that had its own self-energizing effect the multiplied effect made it very sensitive to locking with small initial applications.The following calculation sheets quantify the effect.

[AndrewS]

You're correct. I had the motion of the wheel relative to the mounts backwards. My idea would spread the brakes, not drive them together.

I spent some time looking at the geometry, and I'm having a hard time seeing such a small difference in relative angle having such an effect, but I've never worked on those brakes to see how much oomph they have.

[bicycletricycle]

rohloff hubs are indexed in the hub, they dont feel super crispy but they work no matter what because they have two cables so you are always just pulling. White industries used to make a two cable rear derailleur with indexing in the shifter and linear bearings instead of a parollelogram (how do you spell that?) and i think it felt great but they didn't sell very sell. I still dont understand why. Coombe pedals were really really well thought out, super light, super durable and ultra low stack but they are gone as well. Sweet crank arms had external bearings and a two piece design that predated the current crop of cranks by ten years but they didnt make it. lots of good ideas and quality products seem to go by unnoticed while other lesser products get huge (eggbeater pedals).

[RPS]

The most interesting aspect of braking performance brought up in the technical evaluation (and I haven’t taken the time to look at it in detail so I won’t comment on accuracy of calculations) is that the self-energizing is presented as a cumulative effect of both the “self-energizing Petersen” brake design “PLUS” the orientation of the mounting bosses relative to the rim. Thus it (directly) implies that the orientation of bosses can have a "relative" self-energizing effect on standard everyday brakes as well. Likewise it also (indirectly) implies boss orientation could have a “self de-energizing” effect under the proper geometry.

Just another factor to consider when comparing the same brake on two different bikes and wondering why one rider may think it’s the cat’s meow and another thinks they suck. I doubt the total range of performance can be that different between two applications, but if combined with other factors it can certainly add to a difference in total performance.

[RPS]

Google Roger's 5 factors, they are the keys to innovation diffusion.


Relative advantage
Compatability
Simplicity
Trialability
observability
That's good information, thanks.

I’m wondering where associated negative stigma falls in this list? Would that be considered a “disadvantage” the same as a physical or functional limitation? I'm not sure how that gets classified. :confused:

It seems a lot of new products with clear advantages are sometimes avoided – at least in part -- because they have an associated negative stigma. One that comes to mind is the automatic transmission used in cars. I realize there were initially other factors like lack of “relative advantage” (costs, maintenance, and higher fuel consumption) that kept them from becoming widely accepted, but a major obstacle also had to be the perception that “real” drivers wouldn’t drive an automatic.

Over time as more of the population moved into crowed cities with congested roads the advantages became too great to ignore. That and they became more affordable and more efficient. However, the stigma that real drivers still prefer a stick endures, even though over 90% of cars are automatics. It took many decades for the adoption to be widely accepted.

[Charles M]

There's an innovation that's taking hold...

Auto-sticks and paddle shifters. You can run the cars as auto's and when it's time to hold revs and "really drive" you get the controls that lots of competitive drivers use.



I think the market pretty much always dictates what kills or keeps the next big thing... Marketing doesn't usually make for change unless the product has a real market advantage.

There are lots of things for bikes that sound "better" and it's easy to throw out the idea that things don't happen because companies don't "X"...


The bike industry does change at a reasonable pace (relative to the dollars that support it). Any item that would be of solid benefit will likely make it through.

I think sometimes we're guilty of the same complaint we very frequently have about manufacturers and marketing Hype... We come up with answers to questions nobody is asking, just like companies do. And we think the idea's are fantastic just like the companies do... :beer:

[Tobias]

There's an innovation that's taking hold...

Auto-sticks and paddle shifters. You can run the cars as auto's and when it's time to hold revs and "really drive" you get the controls that lots of competitive drivers use.

Are you talking about clutchless manual transmissions? The concept has advanced enough that the next generation of automatic transmissions for typical family auto use will likely be automated twin-clutch manual transmissions. We’ll drive them just like autos.

The other interesting concept in automatic transmissions are those without a torque converter. Gear changing will be done with planetary gear sets but minus the torque converter which makes them more efficient. To launch the car from a stop the torque converter is replaced with an electric motor in hybrid fashion. The motor takes care of starting to move the car until the first gear can be locked in. Not sure if they even have a reverse gear or if the electric motor takes care of all backwards movement. In principle we may also see a combination of these two concepts.

Like you I love new technologies so it’s all fun to watch.