10

I'm breaking up phase 3 because I'm eager to buy some shocks and working on analyzing my bike's geometry is something I can do at a desk. The problem with the bike is that it doesn't want to turn. It wants to go straight. Good for drag racing, bad for putting a knee down. With some help from some geniuses on the internet and some careful measuring I figured out that my bike's trail is on the long side at around 116 mm and my aim is more like 109mm. (My measurements and math resulted in 125.8 mm of trail, but based on factory specs, adjustments for all the different parts I have, and science done by much smarter people than me, it turns out it's more like 116 mm) So using some amazing math and Excel sheets, (and advice from a former SkunkWorks engineer) I need to add about 20 mm of ride height to the rear which means about 25 mm of length to the shock length to get 20 mm more ride height.

This data here is a record for me, and might not be so useful to anyone reading this unless you're a moto-geek or an engineer.

W-base: 1569 mm*

Head: 62 deg.

Trail: 116 mm

Shock: 320 mm

Front: 254 lbs.

Rear: 261 lbs.

Total: 515 lbs. **

* Rear axle all the way forward.

** Full of fuel and all fluids. Ready to ride.

So TRAIL is the most important aspect when setting up a bike's steering. The closer to zero the quicker a bike wants to turn in. Most sport bikes are in the 95- 120 mm area, and cruisers are out to 125-150 mm. A long trail is very stable, but not so willing to turn. There's a lot of adjustments to make that affect trail, but most of them are not reliably available on this bike. I can't even raise the forks in the triples. I'm not going to be buying new triples, nor am I going to cut the steering head from the frame and weld it on at a different angle. The easiest place to make a change is with the rear ride height with some adjustable shocks. Since I wanted to upgrade my rear shocks anyway (for both looks and performance), this will be an excellent time to kill two birds with one stone.

So what shocks to buy? Good question.

So I have a racing background. I have spent a good 20 years adjusting (mostly factory) suspension to try and go faster. RR, SM, FT, MX, XC. This is a 90% street bike that will probably spend most of it's miles commuting 6.7 miles from my home to my office and back. I'm never going to do a track day with it, and I honestly ride like a grandpa on the street. The only aggressive riding I'll do with the bike will be at the drag strip, and those guys use metal struts in the place of shocks. I'd love to get some fully adjustable (compression/rebound) shocks, but that's in the $1200 range. This is a $500 bike right? I do want something with an external reservoir (looks).

There's no reason at all to put $1200 shocks on a $500 bike. "You can put some Nike Trainers on your Granny, but they're not going to make her go any faster are they?" They'll look good, sure. I think I can get 99% of what I need from a $160 set of shocks.

I would go with the RFY units, but I've read that you might end up sending back 3 out of 4 orders because of the poor quality control. It's a crap shoot. You can get a really nice made set of shocks or you can get something that's made from coat hanger wire and crushed pop cans. They sell these for a lot of scooters, and they do really well there.

The TEC shocks got the most interest from me. They're designed by a Triumph enthusiast who is an engineer in the UK (although they're manufactured in China to keep on budget). I don't want to get on a soapbox about outsourcing manufacturing to China, and the quality of those products. But I believe the quality of the part is dictated by the specification of the designer. China makes a lot of crap for US retailers that want the cheapest possible working part. China also makes some of the finest products in the world. Nike and iPhones.

Anyway, the Triumph guys have given them good reviews for the last 2 years they've been selling them, and they are rebuildable (customizable) and of decent quality control. They might not be any better than the RFY units, but they have a distributor in California, and they answer questions. They must operate on a shoestring, because emails take three days to get answered, and I'm not sure they know much about them anyway.

Ohlins are designed in Sweden, made in Sweden. They are the best.

YSS are US sold, made in Thailand to a high quality. Very good.

RFY probably designed in China, made in China. Mostly crap, but if you're willing to work them over, you can get a good result.

There's also great information from Chris Livengood's site about these budget shocks www.chrislivengood.net

One thing the TEC Bike Parts USA crew did tell me is that I'd need the HD springs to go with the shocks for a bike as heavy as the GS1100. They were an extra $19.00, so I agreed. I got the extra springs, but I thought they messed up. I put the springs on the ground together expecting one to have a much thicker diameter spring wire, but they were the same. (7.75 mm) Every dimension was the same, 200 mm long x 60mm. The only difference was the HD version had only 10 coils, while the STD ones had 11. My pectoralis squeeze test, although highly scientific, resulted in no appreciable difference.

A. I wanted to know if they screwed up and sent me the wrong springs.

B. I wanted to see if I could figure out how to measure any difference.

Enter the Redneck Spring Rate Measuring Device!

Because I'm using inches and pounds to measure the springs, and because Mr. Livengood has a chart of RFY springs in pounds per inch. That's the way I'm working.

My crappy health meter digital scale is not ideal for this work. It locks on a weight if it doesn't change for 1 whole second. So instead of measuring at .25" increments, I just went for one inch and two inches and did my best with what I had.

Before I could do all my measurements and write them down, Chris had mathematically deduced that the HD springs should be 140 lb/in. and he's spot on. He also measured the STD springs to be 125 lb/in. with a proper press, and a proper scale in .25 increments.

Stock: HD:

1" = 122 lbs. 1" = 142 lbs.

2" = 247 lbs. 2" = 269 lbs.

So converting these rates to the more common kg/mm, I get:

125 lb/in = 2.23 kg/mm

140 lb/in = 2.50 kg/mm

Using some online calculators from the various suspension sites online I came up with a optimal spring rate of 3.185 kg/mm. I don't know this for sure yet, but I assume the Nitrogen filled bladder in the reservoir under pressure will make up for that deficiency. And as soon as I can talk my crew (wife and daughter) to hold my bike with me on it and measure the sag rates, I'll know if I need to add or release some pressure in the reservoir bladders.

3.185 kg/mm recommended rate for a dual shock GS1100EZ

(515 lb. bike + 192 lb rider)

As far as looks? I think they look the part, and I'm very pleased. After I have a chance to ride them around for a couple weeks, I'll adjust them up an inch and see if I can notice a difference with the steering.

Cheers!

<I replaced that rusty SA spool allen with a SS one.>

Updated 3.31.14

I stayed up really late last night building my ghetto fabulous chain guard. For some reason the tech inspection at my local Late Night Street Drags requires a chain guard. Not sure why, must be an old rule. Besides, the dangerous part is down below where the chain and sprocket meet. That's where you'll chop off your fingers or toes in a crash. Some bikes have plastic chain guards; do they think that's going to keep an grenading chain from hitting your leg? I don't get it.

Last night I also raised the needles one clip (richer for 1/8th to 1/2 throttle openings) and it's much easier to crack the throttle. Smoothed out that roughness and bog. I might be soon tweaking the pilot fuel screw just a little, but she's getting close to perfect.

Also finally sold my ratty Corbin seat on eBay and went back to my original modified seat. It is really more comfortable, but just doesn't look great. I'll be ordering a new Corbin once I can figure out what I want. (photos get larger if you click on them)

Updated 4.2.14

I felt like I had a baseline feel for the shocks after 100 miles or so commuting and having some fun. So I put in the 30 mm spacers to raise the ride height in the rear. Amazing difference. Bike feels like it has power steering and turns in like a Sport/Touring bike should.

A couple problems with the added ride height: 1. Now my chain rubs on the centerstand. 2. My rear wheel is still on the ground when the center stand is down. It kind of rubbed before, now it's worse. In order for it to clear, I'd have to lower the stop by about 2 inches, so I've decided to just take the center stand off.

My plan was to sell my ratty Corbin seat and buy a new one. It finally sold on eBay and I was all ready to order a new one from Corbin and I think they raised the price? I didn't remember it being $460 (433+25 shipping). I put out some emails, posted up on the GS forum, and found this guy in TN that does amazing work at a great price. I think I'm kind of picky about my seat. 9 years ago I had a guy that was just starting in upholstery do my seat basically for the price of the vinyl. It's comfy, and better than what I had, but the finish is lumpy and not really perfect. My inner thighs get pinched between the seat and the tank and it's just not superfine.

I found this guy Eddie in TN that's been re-doing seats on the side for 30 years. He's really good at it. He's an avid motorcyclist, has owned all the classic bikes over the years, and is just an all-round good man. Before I sent him these pictures, he sent me an idea of a seat. I was blown away with some of his past work, and he's for sure the man for the job. I sent him my seat along with the tail section so he could craft a "solo" type hump into the passenger section, and move the rider's position forward a little. I'm always trying to get my ass closer to the tank for some reason on this bike.

The seat is going to take a week to get there, a few days to get worked on, and another week to get back home, so I decided to tackle the rear sets that I bought. I found a set of ZX12R rearsets and passenger pegs (if I ever need them) for about $100 on eBay. It's going to take some fabrication of adapter plates and some luck.

As you can see, my first cut was not tall enough, so I added a point to the top

First test fitting.

I had to think long and hard about making this cut. It was a "point of no return" for this modification. But I went for it.

Oh, you silly man. Painting these was a little premature. I ended up moving the mounting holes no less than 4 times before I was satisfied. The first time the right side interfered with the exhaust. Had to completely start that one over. The second version was absolutely mirror images of the mounting holes for the rearsets. That's when I realized they are not symmetrical, and the left peg was 1/2" higher than the right. Take the adapter plates off, weld up the holes, and start measuring again.

Found another use for the mini lathe. Trimmed the pan head allen bolts so they'd fit in the rearset recesses.

Finally got them so the rearsets are at the same angle, and the foot pegs are at the same height. There's a guy that goes by the screen name of "isleoman" and I scoffed at him for making plexiglass templates before he had his adapter plates CNC cut out of aluminum. He claimed to have cut 5-6 sets before he was happy. What a rookie, right? Good thing I used steel, and good thing I don't need perfection. I modified these things at least a dozen times. I had them off and on the bike 20 times. Either I'm really picky, or really stupid. But it took me forever to get this right.

All that's left to do with the rearset mod is to fabricate a tailpipe support bracket and bleed the rear brakes out.

2014

Updated 4.16.14

2004

Notice 10 years later the ground is still wet. Welcome to Oregon!