Benito wrote:
The standard bushings are fairly rubbery and allow a fair amount of lateral play when going over bumps or pot holes. As a result of the lateral play I found that with the OEM bushing going over a bump/pothole you would almost not come out of it going in the same direction. The Jettin rear suspension bushings are stiffer polyurethane and do not allow this lateral play. Thus coming out of a pothole I feel that the bike continues to track true and comes out of the pothole in the same direction as when entered. I do not find that it stiffens the ride, nor is it supposed to.
Benito, let me just add to what you said, which is correct.
The urethene is a higher durometer number than the stock bushings. Durometer has a scale from 1 to 100 being the highest. It measures a materials ability to resist permanent indentation, and they have a number of different scales for different materials, like steel, rubber and urethane, etc. At 100, you would expect virtually zero flex at all, and they would be rock hard. The Jettin bushing has a durometer of 90, which is pretty stiff.
Now, to veer totally off topic: I learned about urethane durometer ratings back when I was a semi-pro skateboarder in the late 1970s, and we had softer durometer wheels like the red Kryptonics that rode smoothly (and were very fast) and would flex, but were so soft that they would also chip. Those were a durometer of about 75-78, as recall. The blue Kryptonics were a higher durometer in the 80s, and the green were the highest near 90. I eventually was sponsored by UFO wheels for a time, and they were rock hard well over 90 durometer.
There was also a durometer rating for the bushings in the trucks of the skateboard. We all rode Bennett trucks in the beginning, but the rubber was too soft so everybody would swap out for Tracker trucks bushings, and we eventually switched to Tracker trucks, and then Independants, which I think is still one of the leaders today.
I found some of my old boards in my parent's garage a few months ago and brought them home with me.
One of my first hand made boards. Before this I used cut down water skis they tossed out from Cypress Gradens. After this board I had a Logan Earth Ski.
One of my early Gordon and Smith decks. That one had Bennett trucks and Road Rider 4 wheels, and later OJs.
This was one of my favs. I had it set up with Trackers and UFOs, and I toured out in California at Upland and Spring Valley.
My last board was a Caster with Independents and Green Kyptonics. I probably had 25 boards, but they are all gone but these.
Sorry for the off-topic post, but urethane and durometer are words that bring back a flood of great memories for me.