Rear shock length to order? Analyzing Geometry?

[CivilRock]

When I look at RFY shocks on Ebay I can't tell which is Model 1 & which are 2's. The 2's look like the one to avoid according to

http://chrislivengood.net/wp/?cat=61

so I only want Model 1.
Is there a way to tell the difference? Which ones should I order to fit my gs 1100's?

If you go to Chris Livengood's review of the Model 2, read the comments at the bottom. http://chrislivengood.net/wp/?p=1304#comments There's a guy named Eric that got word from a reseller that RFY has addressed the missing port issue with the Rebound adjustable version 2.0. They can be identified by the amazingly awful color scheme seen in the pic below. The tell tale sign of the Model 2 is the presence of the rebound adjustment clicker just above the clevis.

If I were to buy these, I would fully disassemble them, check for obvious flaws, assembly errors, and missing components. I've read several reviews on them and come to the conclusion that they are a good unit if you're lucky. The quality control is apparently non-existent. Look for casting flaws, machining errors, assembly missteps, and even missing ports. Plan on replacing the fluid and getting them charged correctly with Nitrogen.

-Kevin

[CivilRock]

posplayr,
I really appreciate your numbers.

I think were my situation might be different is with the GSXR1100 swingarm I have on my bike. It puts my rear axle about 4" back from the stock GS point.

As I've learned, change in wheelbase alone will change the trail and rake numbers. I think the slight change in what I see from stock reflects that longer swingarm.

On another note: I noticed at the drag strip a lot of the guys were using straps to hold down the front ends on their street bikes. It makes sense right?
Backstory: So I raced Supermoto for many years and we all had "holeshot" devices borrowed from the MX industry. It's a little clip on your fork protector that holds down the forks until you hit the brakes (or slam down a wheelie). I used one, and it made a huge difference in my starts. We had a race with a really long start and several people had violent crashes at the end of the straight before the braking zone, and we finally figured out that the holeshot device was creating a very unstable geometry at speed. Now that I have a grip on the idea of "Trail". I believe they were basically eliminating the bike's trail and tank slapping themselves to the ground at 70+ mph.

Would these straps create the same dangerous lack of trail on an R1? Maybe not. The MX holeshot device would take out 8-10 inches of travel on a dirt bike, and only 2-2.5 on a street bike. Just my guess.

-Kevin

[posplayr]

posplayr,
I really appreciate your numbers.

I think were my situation might be different is with the GSXR1100 swingarm I have on my bike. It puts my rear axle about 4" back from the stock GS point.

As I've learned, change in wheelbase alone will change the trail and rake numbers. I think the slight change in what I see from stock reflects that longer swingarm.

On another note: I noticed at the drag strip a lot of the guys were using straps to hold down the front ends on their street bikes. It makes sense right?
Backstory: So I raced Supermoto for many years and we all had "holeshot" devices borrowed from the MX industry. It's a little clip on your fork protector that holds down the forks until you hit the brakes (or slam down a wheelie). I used one, and it made a huge difference in my starts. We had a race with a really long start and several people had violent crashes at the end of the straight before the braking zone, and we finally figured out that the holeshot device was creating a very unstable geometry at speed. Now that I have a grip on the idea of "Trail". I believe they were basically eliminating the bike's trail and tank slapping themselves to the ground at 70+ mph.

Would these straps create the same dangerous lack of trail on an R1? Maybe not. The MX holeshot device would take out 8-10 inches of travel on a dirt bike, and only 2-2.5 on a street bike. Just my guess.

-Kevin

If you go into the spreadsheet on the Trail tab, there is a column for wheelbase. Make your adjustment based on increase in swing arm length and you will see the "Rake" angle change based on wheelbase and "rear Lift" (i.e. shock extension from stock). The Rake angle is added to the "Head" angle to compute trail.

Nominal wheel base does not even enter into the equation unless you couple it with a rise in the rear or rear shock extension. Even then it is the shock extension that dominates in the change of trail.

I updated the spreadsheet a little to see where you are (I'll forward it).

To achieve this:

I'd like to decrease the trail by about 17 mm and get it in line with a sport and ST bikes at 109mm.

You are close as is unless you really have the front forks at one extreme or another. According to my calculations using the 1150 triple clamp, 17" wheel with 120/70-17 and the other nominal dimensions from the GS1100EZ you have 113mm of trail.

If you raise the tail 0.75" that will give you 109mm of trail

Jim

[CivilRock]

Thanks. I'm glad you sent the Excel sheet because I wasn't figuring it out.

Jim, you know... sometimes I just have to learn the hard way.

I have about 0.5 mm of fork tube showing on my triple.

I'm going to make sure my new rear shocks can adjust ride height at least .75" (20mm)

I can't seem to get any response from the TEC people. Might have to try something else.

I'm amazed at the formulas behind that little Excel sheet you wrote.

-kevin

[posplayr]

Thanks. I'm glad you sent the Excel sheet because I wasn't figuring it out.

Jim, you know... sometimes I just have to learn the hard way.

I have about 0.5 mm of fork tube showing on my triple.

I'm going to make sure my new rear shocks can adjust ride height at least .75" (20mm)

I can't seem to get any response from the TEC people. Might have to try something else.

I'm amazed at the formulas behind that little Excel sheet you wrote.

-kevin

0.75 is the seat height change not the shock change.

Adding 1" to the shock gets you 0.87" at the rear, so look for at least an 1" shock length increase. The Ohlins is 30-50mm


While, I'm far from an Excel guru, back in the late 80's I worked at a company that forbade system engineers from "programming", (i.e, in Fortran, C or Basic) all of which I was fluent in along with some others. So for about 6 years everything had to be done in Lotus 123 (to keep us focused). I'll just make mention we did some pretty interesting stuff for not having a real programming language and learned a few tricks along the way. It was a small company building commercial multi mode air to ground missiles from scratch.

[loud et]

Not to thread jack this ...but its related...
Is a 360 mm (14.173 inch) rear shock too long for a GS?
In my instance its for a my 650E

[CivilRock]

TEC shocks ordered

I just sent $177 to TEC bike USA for a couple of reservoir shocks.
$139 shocks
$19 HD springs
$19 shipping

They did say that I'd need the optional heavier springs, which Dallas (Grand Rouge) said I would need. They also come with little ~1" spacers that I assume are a byproduct of being used on several different Triumph machines. But that will help me try out some different ride heights and even spring rates.

I found tons of information on my own and from Grand Rouge here, but hardly any answers from the people at TEC Bike USA. I'm assuming this is a side gig for them or they're just getting pounded with emails/questions. But it is a 3 day turn time on any emails.

I watched this 6 part video series from RaceTech Suspension:

http://youtu.be/Xne5oazDHKo

I've used Racetech stuff before, and I like their style of helping the DIY guy get it done. I'm probably just going to throw them on the bike and see how they feel. But if there's any problems, I plan on taking apart the shocks, inspecting the work, changing out the fluid, and charging the bladder with Nitrogen.

I know these are made in China, but I'm hoping that the designers in the UK are specifying a greater quality than the RFY units that seem to vary quite a bit in quality control. And to be honest, I like the simple colors of the TEC unit compared to the technicolor vomit colors available from RFY.

BTW Jim, I looked at my forks and there's no way to RAISE <edit) the forks. The 1150 forks have a fitting that balances the air between the two sides and that fitting is right under the top triple. I guess I could braze that hole shut and remove the fitting if I was really wanting to lower the front. But I'm already suffering from clearance issues, and from the sounds of it, adding 1" to the rear might be all that this guy needs.

Oh, and filling my tires properly will surely help matters.

-Kevin

[posplayr]

I just sent $177 to TEC bike USA for a couple of reservoir shocks.
$139 shocks
$19 HD springs
$19 shipping

They did say that I'd need the optional heavier springs, which Dallas (Grand Rouge) said I would need. They also come with little ~1" spacers that I assume are a byproduct of being used on several different Triumph machines. But that will help me try out some different ride heights and even spring rates.

I found tons of information on my own and from Grand Rouge here, but hardly any answers from the people at TEC Bike USA. I'm assuming this is a side gig for them or they're just getting pounded with emails/questions. But it is a 3 day turn time on any emails.

I watched this 6 part video series from RaceTech Suspension:

http://youtu.be/Xne5oazDHKo

I've used Racetech stuff before, and I like their style of helping the DIY guy get it done. I'm probably just going to throw them on the bike and see how they feel. But if there's any problems, I plan on taking apart the shocks, inspecting the work, changing out the fluid, and charging the bladder with Nitrogen.

I know these are made in China, but I'm hoping that the designers in the UK are specifying a greater quality than the RFY units that seem to vary quite a bit in quality control. And to be honest, I like the simple colors of the TEC unit compared to the technicolor vomit colors available from RFY.

BTW Jim, I looked at my forks and there's no way to lower the forks. The 1150 forks have a fitting that balances the air between the two sides and that fitting is right under the top triple. I guess I could braze that hole shut and remove the fitting if I was really wanting to lower the front. But I'm already suffering from clearance issues, and from the sounds of it, adding 1" to the rear might be all that this guy needs.

Oh, and filling my tires properly will surely help matters.

-Kevin

Yep that is first priority.


Anxious to see how the shocks work out.

[themess]

....While, I'm far from an Excel guru, back in the late 80's I worked at a company that forbade system engineers from "programming", (i.e, in Fortran, C or Basic) all of which I was fluent in along with some others. So for about 6 years everything had to be done in Lotus 123 (to keep us focused). I'll just make mention we did some pretty interesting stuff for not having a real programming language and learned a few tricks along the way. It was a small company building commercial multi mode air to ground missiles from scratch.

In the late 80s, Firestone's IT policy didn't let anyone other than clerical staff have word procesors. Engineers wrote their documents using Lotus 123.

[posplayr]

In the late 80s, Firestone's IT policy didn't let anyone other than clerical staff have word procesors. Engineers wrote their documents using Lotus 123.

Wrote documents in 123??? Someone must have thought enginerrs have a hard time forming sentences.

This was late 1987,

I left a job where every two engineers shared a VT100 VAX terminal and myself, I also was the curator of what was called the "Modern Control Work Station". It was a 8086/8087 PC I has at my desk that had a TI TMS32010 DPS add-in board that we could write "C" or assembler and download to try things out. On the VAX, we could edit files and compile and run FORTRAN or BASIC I guess (don't remember). I probably had an early version of MATLAB and the latest Microsoft C compiler circa 1985. Turbo Pascal was also popular at the time.

At the new job I was given a new 286 PC, with Word Perfect to write documents and Lotus to do analysis. The point was to stay focused on "performance" and not get wrapped up in simulations. While, the whole company was a high stakes experiment, this also was a new technique to focus Systems engineers on "performance" and performance trades rather that getting wrapped up in simulations.

We also had Mac architecture drawings, but the secretaries would draw them according to out markups.

[CivilRock]

10 CLS
20 Cancel program "Engineer Glory Days"
30 Run "GS Talk"
40 End

I wish I could be more authentic (and funny) with my basic programming. We had a Radio Shack TRS-80 when I was a kid, and I learned about 2 tricks on it before I went out to the garage and started taking apart stuff.

-Kevin

[themess]

Wrote documents in 123??? Someone must have thought enginerrs have a hard time forming sentences.

This was late 1987,

I left a job where every two engineers shared a VT100 VAX terminal and myself, I also was the curator of what was called the "Modern Control Work Station". It was a 8086/8087 PC I has at my desk that had a TI TMS32010 DPS add-in board that we could write "C" or assembler and download to try things out. On the VAX, we could edit files and compile and run FORTRAN or BASIC I guess (don't remember). I probably had an early version of MATLAB and the latest Microsoft C compiler circa 1985. Turbo Pascal was also popular at the time.

At the new job I was given a new 286 PC, with Word Perfect to write documents and Lotus to do analysis. The point was to stay focused on "performance" and not get wrapped up in simulations. While, the whole company was a high stakes experiment, this also was a new technique to focus Systems engineers on "performance" and performance trades rather that getting wrapped up in simulations.

We also had Mac architecture drawings, but the secretaries would draw them according to out markups.

IT classified everyone into three groups: Clerical, engineering or management/accounting. Engineers used HPs and Lotus. Management/accounting used IBMs and got some accounting package. Clerical used dedicated word processing word stations, made by some company that was merged out of existence by 1990. Of course, above some arbitrary salary grade, anything was available. This was just after 286s had come out.

I had just returned from three years in Mexico, and was trying to find an appropriate slot. I wasn't really classified and fell between the cracks. I had my CP/M Kaypro at home, and used WordStar on it. So I bought a copy of WordStar for MS-DOS and a copy of a 1-2-3 clone. The clone was much nicer than 1-2-3. To print, 1-2-3 required exiting and opening a separate program. The clone allowed printing from within the spreadsheet. So I did my computer work more efficiently. I showed the people I worked with how, but they stuck with the cludgy software. Eventually, I was riffed. I had turned down an open slot which I probably should have taken. The main reason is that people focused so tightly on their own narrow responsibilities that they didn't notice the forest or great improvement opportunities, and management kept it that way. Sticking with cludgy software was a small example of that way of thinking.

The only programming I've done was in BASIC. I first did it in a factory. Accounting received reports from corporate via TeleType terminals. (Yes, honest to God TeleType) The terminals were attached to an IBM 370 in a different state, by dedicated phone lines. The trick to using them was to eliminate typos, as there was no monitor or ability to edit out any typo. So I wrote my program to echo back each line of entered data before the data was posted for processing. That, and much typing practice. The program reduced a full day of desk work to about a half hour. I repeated the same thing later on my Kaypro. Any modern spreadsheet would replace the programs..

So, when I apply for jobs, I always claim excellent computer skills, even though the HR people mean MS Office. They have no idea.

[CivilRock]

Got the shocks on Friday, and set out to get them mounted up before my wife got home.

First job was to swap the springs to the HD ones that I paid an extra $19 for. I was rushed, but I wanted to check out the difference between the springs. First off, I removed the stock spring and set it next to one of the HD springs... They're the same length, the same thickness spring ( I measured 7.75 mm for both). The only difference is the HD spring has one less coil. I tried pushing on them on the floor but I couldn't tell a difference in spring rate with the highly scientific method of using my palms.

The next thing I did was compress the shock without the spring, over and over again to see if there was enough oil in there, and see if the shock would fully extend on it's own without the spring. I couldn't work out all the air bubbles (you can feel it) and the shock would only extend about 60% of the way out on it's own without the spring.

My swingarm shock mounts were fabricated by me, and apparently are just slightly thinner than the stock GS mounts. I did have to grind a hair off the bushings I put in the mounts, but that was easy. I also had to round off the bottom corners of the clevis so it wouldn't dig into the shock mount welds, but that too was pretty easy. Both issues that no one else in the world would ever share with me because of my homemade swingarm.

Despite the low bladder pressure, unverified HD springs, and seemingly ill oil level, they feel pretty good. Just bouncing on the bike it feels pretty even with the front end and the test ride feels just the same as the old shocks. I think my old stockers were past their prime, and the only way I could really tell a difference was bouncing the bike in the garage. I can guarantee you I'll never have this bike over at full lean, and I'm not sure if I can find some braking bumps to really test the rebound, or see if the shock is "packing"...

I think they look sweet. There's at least 1" of adjustment in the bottom clevis, and if that's not enough, there's a +1" spacer that came with them. I can't really see a downside. Yes, if I'm feeling frisky some day I might take them apart, go for some new 10wt oil and a calibrated Nitrogen charge, but until then, I'm just going to enjoy the beauty.

-Kevin

This was inside a large flat rate USPS box.


After I removed the packing and plastic bags.


The included spacers should you need them.


Oh yea. Me likey.


<-- I have got to replace those rusty bolts in the swingarm spools!

[CivilRock]

0.75 is the seat height change not the shock change.

Adding 1" to the shock gets you 0.87" at the rear, so look for at least an 1" shock length increase. The Ohlins is 30-50mm

So I had a chance this week to get a little more aggressive with the GS on some turny roads. The carbs are adjusted to a point where I'm more comfortable with it, and it was somewhat dry this week. So I feel like I have a baseline for the new shocks without the ride height adjustment. They do feel a little underdamped (if that's a word). Boingey (I know that's not a word)

This morning I threw on the spacers, which are +1-1/8" (+30 mm). My aim is 1", but I didn't want to adjust the clevis out that far. If 30mm is too much, I'll turn the spacers down on my lathe.

One item to note: The center stand is very easy to use now that the rear wheel doesn't come off the ground. Not sure if this is good or bad yet.

No ride report yet. I just like posting pictures.

-Kevin


BTW, yes that is my ghetto fab chainguard. PIR Late Night Drags requires it. I had no idea what the stock one looked like, and it's just for when I go to the track.

[posplayr]

Looks good, anxious to see how it feels after you get the tires properly pressurized and your sag sorted. It still weights 500 lbs, but should be confidence inspiring for spirited riding.
With the spacer a before after of the 1" should be telling.