When the brain is disconnected

[faffi]

Happens to me all the time. Like yesterday, when I was going to put the pork ribs into the oven and forgot I had added water to the tray. The rib and tray came along just fine, but a good portion of the water decided to prove that Newton was right...

But it can also happen to professionals. I am going through old M/C magazines, and today I read an article about how to improve the then current VFR750 as well as the GPZ1000R Ninja.

For the Honda, they changed the fork springs, and the maker delivered a set of straight wound springs plus spacers. In addition, the kit came with 4 short and very stiff springs. According to the instructions, springs plus spacer would yield the softest setup. To go firmer, you could add one firm spring on each side and cut down the spacer accordingly. For the stiffest ride, you should discard the spacers and use the standard spring plus the two firm ones in each leg. And the article claimed that the only way they could get a modicum of comfort, was with the spacers and the standard spring. Preload was the same in all instances.

Now, even the stiffest spring will compress, something a spacer will not. Also, the longer a spring become, the softer it will get. So unless it is my brain that is disconnected again. the stiffest ride should be with the standard springs and full length spacers.

When it came to the Ninja, they felt that the overall gearing was too tall in order for the bike to reach 160 mph at its redline. This "tall" gearing (4000 rpm @ 60 mph is not what I personally consider tall gearing, but whatever) made the liter bike sluggish in acceleration in its top three tallest gears, struggling to keep up with 750s. After fitting a rear sprocket with three additional teeth - reducing theoretical top speed from 160 to 146 mph - acceleration from 45-70 mph in 4th gear dropped from 6 to 2.88 seconds! That could only happen if the bike was sitting in a big hole in the powerband with the stock gearing. However, after this gearing change, the Ninja was now a lot quicker in 6th gear than it was previously in 4th. Which does not compute. Either the conditions had changed dramatically, or they used a different test bike, indicating something was off during the original full road test of the bike.

In this case, the collective brains of the magazine staff was clearly out to lunch. They should at least understand this when they, after learning the Ninja was too busy with the low gearing, changed to a one-tooth extra rear sprocket (compared to stock) and the acceleration was still 40-45% better than what they had achieved in the original road test.

[SIR REAL ED]

The gearing is simple math.  If the new sprockets resulted in a new sixth gear that was lower than the original fourth gear, it makes sense.  If not, they were wrong.

IIRC, the original GPz900 had a very close ratio gearbox.

Springs can be difficult to understand.  For my simple mind, the following visualization always clears my confusion.

Imagine straightening out the spring wire.  One end is anchored so the wire become a horizontal, cantilever beam.  Compression of the spring with a load applied in it's original configuration, will be identical to the vertical deflection of the free end of the imaginary horizontal beam with an equal load applied.

Thicker wire results in a stiffer beam, obviously

Thinner wire result is a less stiff beam, obviously. 

Shorter wire is a shorter, stiffer beam.  The can be accomplished with less spring coils or a smaller outside diameter (OD) of the spring, while keeping the same wire diameter.

Longer wire is a longer, less stiff beam.  This can be obtained by more spring coils, or increasing the outside diameter (OD) of the spring, while keeping the same wire diameter.

My most common brain checkout these days is looking for something I remember as green, while the item I am looking for is actually blue and is sitting right in front of me.

[faffi]

Big difference in gearing; 1.33:1 in 4th and 1.03:1 in 6th, so about 30%, whereas the changes in final drive ratio was at first 7.5%, then reduced to just 2.5%.

I think of spring rates like this (for straight wound springs): Double the length and the rate is halved. Halve the length, and the spring rate is doubles.

[SIR REAL ED]

Big difference in gearing; 1.33:1 in 4th and 1.03:1 in 6th, so about 30%, whereas the changes in final drive ratio was at first 7.5%, then reduced to just 2.5%.

I think of spring rates like this (for straight wound springs): Double the length and the rate is halved. Halve the length, and the spring rate is doubles.

Yep.  It is all about the wire length.  The same holds true for progressive rate springs.

If the wire diameter is uniform, spring rate is determine by length of wire per unit of spring length.

[YellowDuck]

The one I always have a hard time accepting is that if the fork is extended to the point where the topout spring is engaged, it becomes stiffer (i.e., the spring rates *add*).  It's equivalent to having springs in parallel.

[SIR REAL ED]

The one I always have a hard time accepting is that if the fork is extended to the point where the topout spring is engaged, it becomes stiffer (i.e., the spring rates *add*).  It's equivalent to having springs in parallel.

Me confused, "if the fork is extended to the point where the topout spring is engaged" ie: you are pulling a wheelie or the bike is jacked up where the front wheel is off the ground, the the only force on the compression fork spring is the preload from the fork cap.

The topout springs are compressed when the fork is in tension.  The regular fork springs are compressed when the fork is in compression.

As they used to say on Laugh-In:  "Different strokes for different folks!"

Springs in series function like resistors in parallel, spring rate (force/distance) is reduced.  Springs in parallel function like resistors in series, spring rate is increased.

Please explain.  Thanks in advance.

[Tkelly]

How were the pork chops?

[faffi]

The one I always have a hard time accepting is that if the fork is extended to the point where the topout spring is engaged, it becomes stiffer (i.e., the spring rates *add*).  It's equivalent to having springs in parallel.

Decades ago, I read an article about this. And failed to fully understand how and why, I just had to accept it. I wonder if it was in RaceTech's Suspension Bible

[Moparnut72]

I watched a video last night, more of a podcast. It was produced by CanyonChasers which was about an hour long. It was all about suspension, including racing, track days and street riding. He and his co-host had Fuzzy from Fuzzy Suspensions on the show. There was a lot of discussion about setting up suspensions. Well worth watching, it sure opened my eyes as suspension setup is not one of my strong points. One thing that really surprised me was that he said that self adjusting suspensions like the one on the V100 S is a no no. He goes into details as to why. Better off to have a standard suspension and set it up to fit the rider and how he rides. I fiddled with the suspension on my V100 standard and thought I was totally out of wack as to what should be done. It turns out for what I wanted I was on track. Well worth watching, I plan on watching again.
kk

[guzzisteve]

When mine does this I used to smoke a big bowl to solve it. Now no smoking so have to restructure that process. HA GOOD LUCK

[SIR REAL ED]

When mine does this I used to smoke a big bowl to solve it. Now no smoking so have to restructure that process. HA GOOD LUCK

Now that we are surrounded by virtual reality 24/7, spending money on halucinogenic drugs seems frivolous!

Coast to Coast AM.... Caravan to Midnight..... Wildguzzi.com..... virtual brain jump starting aids are everywhere!

[faffi]

I watched a video last night, more of a podcast. It was produced by CanyonChasers which was about an hour long. It was all about suspension, including racing, track days and street riding. He and his co-host had Fuzzy from Fuzzy Suspensions on the show. There was a lot of discussion about setting up suspensions. Well worth watching, it sure opened my eyes as suspension setup is not one of my strong points. One thing that really surprised me was that he said that self adjusting suspensions like the one on the V100 S is a no no. He goes into details as to why. Better off to have a standard suspension and set it up to fit the rider and how he rides. I fiddled with the suspension on my V100 standard and thought I was totally out of wack as to what should be done. It turns out for what I wanted I was on track. Well worth watching, I plan on watching again.
kk

Will watch it later. I am interested to learn how the advice compare to Moss and RaceTech. Link https://www.youtube.com/watch?v=ueO01ILy1TQ

[turboguzzi]

Well, some magazines had good technical editors, some didnt,

the only people i reckon knew what they were talking about were Kevin Cameron, John Robinson and Massimo Clarke.

If you still like reading rather than watching videos, here's the link to the suspension bible:

http://didier.clergue.free.fr/gsxr/livres/Livre_Race_Tech%27s_Motorcycle_Suspension_Bible.pdf

[guzzisteve]

Sorry I don't do virtual reality or social media anything, this place is the closest I get to any of it, I'm Mostly ANOLOG do you remember what that is, I doubt it. Your Utube world does not exist except in your own reality NOT mine. I do things I do not watch others do anything, does not interest me.

[Moparnut72]

Will watch it later. I am interested to learn how the advice compare to Moss and RaceTech. Link https://www.youtube.com/watch?v=ueO01ILy1TQ

Thanks for posting the link. I have not been able to do it with this stupid Chrome Book.
kk

[SIR REAL ED]

Well, some magazines had good technical editors, some didnt,

the only people i reckon knew what they were talking about were Kevin Cameron, John Robinson and Massimo Clarke.

If you still like reading rather than watching videos, here's the link to the suspension bible:

http://didier.clergue.free.fr/gsxr/livres/Livre_Race_Tech%27s_Motorcycle_Suspension_Bible.pdf

I would add Cook Neilson, Joe Minton, and Phil Schilling to that list.

Great book!  Thanks for posting.

[faffi]

Another suspension video, this one breaks things down to the very basics in order to let people understand the concept of suspension https://www.youtube.com/watch?v=cHeqZGRzzu4