SJRoome
Registered user
Hi
After my 1989 R100GS failed its MoT because of a leaking rear shock absorber, I decided to replace it with a HyperPro 3D shock. I also decided to upgrade the front forks with HyperPro’s upgrade kit. The story of the installation of these upgrades is given here and here.
I am by no means an expert on motorcycle suspension or a very good rider but I thought my experience of the upgrade might help others faced with the same choices.
When the bike failed its MoT I was not disappointed because it forced me to upgrade the rear shock, a decision I have been thinking about for years. I have been experimenting every now and then with the suspension. I am sure you all know that with the standard fork springs the usual fork oil is SAE 10W both sides and that one side controls compression and the other the rebound. In 2009 I changed to “The Millichap cocktail” which is 15W left fork and 16.75W right fork. This improved the handling but I found the ride rather hard and I changed the left leg back to 10W a year later.
Other than the oil in the right hand fork the bike was pretty standard. The tyres are Metzler Enduro 3 Sahara. The front is new and is at a pressure of 2.2 Bar. The rear has about 50 miles wear from new and is at 2.5 Bar.
I have tested the bike both before and after the upgrade on a circuit of local roads that I know well. I was particularly interested to see how the bike felt on a piece of the A323 heading north into Fleet from Farnborough. The road surface has become particularly nasty over the last few years. The surface is tarmac with embedded gravel that causes the Metzlers to vibrate. The road has been dug up right down the middle of the northbound lane by a utility company and they have somehow created a surface which undulates up and down with a period of a couple of yards together with ripples every couple of inches.
With my old shock and forks riding on this was a pretty scary experience. The front of the bike was vibrating at several different frequencies simultaneously. It also felt difficult to control the direction the bike was going in as the edge of the dug up area would pull the bike about. I found the best way to get through it was to choose a position in the centre of the lane, deliberately relax and accept that the bike was going to vibrate a lot and drift about your intended line.
I had been advised that changing the rear shock improved the handling (http://www.ukgser.com/forums/showthread.php/184860-Twitchy-Forks-weaving-at-45-mph) but I was pretty dubious as there did not seem to be any play in the BMW unit and it appeared to be damping effectively. Shocks are also very expensive compared to other airhead upgrades I have been thinking of investing in such as lowered footrests.
The MoT Failure forced me to do something. I considered putting in another BMW damper unit or changing to an Ohlins but eventually chose HyperPro recommended by UKGSER Ras Thurlo because of good reviews and the unit appeared to be very rugged.
After I fitted the new shock I rode about a bit to get used to the bike and then headed for my test circuit. The rear shock was stiffer than the standard unit but more controlled. When riding over a rough surface I became aware of the seat beneath me absorbing the small vibrations (I have had gel inserts fitted). The most noticeable change was when I rode the nasty stretch described above. The bike’s tendency to get thrown off line had completely gone. The front fork was still passing on all sorts of nasty vibrations but I felt more in control. I had planned to leave the fork upgrade until I had played with the shock for a while but the difference was so great I wanted to upgrade the front as soon as possible.
After I upgraded the forks I went for a short test ride. The upgrade seemed good match for the shock as it was also stiff but controlled. I find that the experience of riding my bike depends on how the carbs pick up at very small throttle openings and I was experiencing some vibration from an in-balance, so I treated my carbs to a thorough clean. I did not balance them but I checked the cable clearances were the same on both sides. The carbs actually appeared very clean inside but I must have removed something as the engine ran far better afterward.
Now for that test ride. I find how I ride depends a lot on how confident I am feeling. If I am nervous in a turn my hands are resting on the clutch and brake levers and my feet are fluttering over the rear brake pedal and the bike can feel twitchy. At the best times I am hardly aware of turning at all and the only way to know that the bike is banked is because the horizon has moved from horizontal.
At the start of the test ride I was still a bit nervous and I misjudged the gears on a couple of turns but as the ride progressed I settled down. By the time I reached the nasty section I was enjoying myself. Once on it I felt totally in control. The rear shock meant the bike was on the line I had chosen and showed no tendency to be pushed off it. The front fork absorbed the high frequency ripples and was passing on the information that the road was undulating rapidly but gave great confidence that everything was under control. It was an unusual experience but after a while I found that I was drifting into the relaxed state. When I arrived home I was grinning from ear to ear and wondering what that section would be like 5 mph faster!
Steve
After my 1989 R100GS failed its MoT because of a leaking rear shock absorber, I decided to replace it with a HyperPro 3D shock. I also decided to upgrade the front forks with HyperPro’s upgrade kit. The story of the installation of these upgrades is given here and here.
I am by no means an expert on motorcycle suspension or a very good rider but I thought my experience of the upgrade might help others faced with the same choices.
When the bike failed its MoT I was not disappointed because it forced me to upgrade the rear shock, a decision I have been thinking about for years. I have been experimenting every now and then with the suspension. I am sure you all know that with the standard fork springs the usual fork oil is SAE 10W both sides and that one side controls compression and the other the rebound. In 2009 I changed to “The Millichap cocktail” which is 15W left fork and 16.75W right fork. This improved the handling but I found the ride rather hard and I changed the left leg back to 10W a year later.
Other than the oil in the right hand fork the bike was pretty standard. The tyres are Metzler Enduro 3 Sahara. The front is new and is at a pressure of 2.2 Bar. The rear has about 50 miles wear from new and is at 2.5 Bar.
I have tested the bike both before and after the upgrade on a circuit of local roads that I know well. I was particularly interested to see how the bike felt on a piece of the A323 heading north into Fleet from Farnborough. The road surface has become particularly nasty over the last few years. The surface is tarmac with embedded gravel that causes the Metzlers to vibrate. The road has been dug up right down the middle of the northbound lane by a utility company and they have somehow created a surface which undulates up and down with a period of a couple of yards together with ripples every couple of inches.
With my old shock and forks riding on this was a pretty scary experience. The front of the bike was vibrating at several different frequencies simultaneously. It also felt difficult to control the direction the bike was going in as the edge of the dug up area would pull the bike about. I found the best way to get through it was to choose a position in the centre of the lane, deliberately relax and accept that the bike was going to vibrate a lot and drift about your intended line.
I had been advised that changing the rear shock improved the handling (http://www.ukgser.com/forums/showthread.php/184860-Twitchy-Forks-weaving-at-45-mph) but I was pretty dubious as there did not seem to be any play in the BMW unit and it appeared to be damping effectively. Shocks are also very expensive compared to other airhead upgrades I have been thinking of investing in such as lowered footrests.
The MoT Failure forced me to do something. I considered putting in another BMW damper unit or changing to an Ohlins but eventually chose HyperPro recommended by UKGSER Ras Thurlo because of good reviews and the unit appeared to be very rugged.
After I fitted the new shock I rode about a bit to get used to the bike and then headed for my test circuit. The rear shock was stiffer than the standard unit but more controlled. When riding over a rough surface I became aware of the seat beneath me absorbing the small vibrations (I have had gel inserts fitted). The most noticeable change was when I rode the nasty stretch described above. The bike’s tendency to get thrown off line had completely gone. The front fork was still passing on all sorts of nasty vibrations but I felt more in control. I had planned to leave the fork upgrade until I had played with the shock for a while but the difference was so great I wanted to upgrade the front as soon as possible.
After I upgraded the forks I went for a short test ride. The upgrade seemed good match for the shock as it was also stiff but controlled. I find that the experience of riding my bike depends on how the carbs pick up at very small throttle openings and I was experiencing some vibration from an in-balance, so I treated my carbs to a thorough clean. I did not balance them but I checked the cable clearances were the same on both sides. The carbs actually appeared very clean inside but I must have removed something as the engine ran far better afterward.
Now for that test ride. I find how I ride depends a lot on how confident I am feeling. If I am nervous in a turn my hands are resting on the clutch and brake levers and my feet are fluttering over the rear brake pedal and the bike can feel twitchy. At the best times I am hardly aware of turning at all and the only way to know that the bike is banked is because the horizon has moved from horizontal.
At the start of the test ride I was still a bit nervous and I misjudged the gears on a couple of turns but as the ride progressed I settled down. By the time I reached the nasty section I was enjoying myself. Once on it I felt totally in control. The rear shock meant the bike was on the line I had chosen and showed no tendency to be pushed off it. The front fork absorbed the high frequency ripples and was passing on the information that the road was undulating rapidly but gave great confidence that everything was under control. It was an unusual experience but after a while I found that I was drifting into the relaxed state. When I arrived home I was grinning from ear to ear and wondering what that section would be like 5 mph faster!
Steve
