99Birdman Posted October 19, 2006 Share Posted October 19, 2006 Not being able to affford the Traxxion cartidges for my forks, I shipped them to Dan Kyle to have them reworked. If you're not familiar with who Dan is, do a search here but he is highly respected in the perormance community. He has been highly recommended by sevearl board members who have worked with him in the past. I just spent about 45 minute talking with Dan about suspension in general and our forks specifically and he pointed out several things which seem to run counter to the conventional wisdom I have seen: The stock CBR1100XX forks are very undersprung and underdampenned. I know the general thoughts have been that they are overdamppened but he says that is not the case. He believes Honda and most other manufacturers rely on too soft a spring with too much preload (effectively creating a stiffer spring with less travel) and too heavy weight of oil. The stock spring is a .92kg and very mildly progressive (as opposed to the .89 most of us thought it to be). This is based on multiple measurements he has taken with a calibrated measurement tool. His put in an Ohlins spring equivalent to a .97kg for my weight (170-175). This is interesting since the spring recommended by Wilburs in the group buy was a .9kg which means I actually went softer. Add to that, the fact that I used the recommended oil weight of 2.5 and he said my oil looked terrrible and might as well have been water (this after less than 2000 miles). He also recommend as sag range of between 35mm-50mm (mine are set at 40mm). 30-35mm is way to little he feels. Another interesting point he made was that riding 2 up or with alot of luggage frequently would actually call for softer fork springs rather than stiffer due to the location of the passenger above or behind the rear axle which actually takes weight off the front end and causes stiff springs to be topped out often. As far as the rear, he said the stock springs are not bad, but the linkage is designed to accomodate, as much as possible, the fact that Honda could not anticipate the weight of the rider and uses way too much preload to achieve proper sag. They rely on a very progressive linkage to achieve close spring rates at extremes of suspension travel. For a lot of twisty riding, a less progressive, more linear linkage would be better. While he has used Blackbird linkages on F4's in the past, he couldn't, offhand, recommend a swap that would improve ours. In general, Dan is a great guy to do business with and he will spend as much time as you need to make sure you understand what he does to the forks (from polishing components to changes to shim stacks). I shipped mine to him on Monday and will have them back Friday (we're both in California but he turns them around in 1 day). Total cost was $440 including Ohlins springs plus shipping. Add the Penske shock comming in tomorrow and I'm ready for track day next weekend. Quote Link to comment Share on other sites More sharing options...
rideonXX Posted October 20, 2006 Share Posted October 20, 2006 Thanks for the write up-----information worth considering for sure. The statement about the stock spring being slightly progressive came as a surprise. The comment about stock being underdampenned with thicker oil leads me to believe there was a misunderstanding in the discussion. Thicker oil increases damping (less oil can go through a given opening for the same time period). All a person has to do is pour some 15wt in their Bird forks to find out what 'choppy' ride means. That would be overdampenned. As for the effect of preload on single rate (not progressive) springs----it may appear to change the rate to the casual observer----but it does not. From the Sportbike Performace Handbook by Kevin Cameron page 106----"When thinking about preload, alsways remember that adjusting preload up or down simply changes the height at which the bike rides. It does not make suspension stiffer or softer. The reason many riders intuitively feel preload changes adjust stiffness is that a bike with a lot of preload does not move as easily when they sit down on it. It takes more pressure to begin to compress the suspension. This is not the same as a stiffer spring!----" Dan Kyle does have excellent credentials---he does know his business. The communication process can create difficulties, especially when dealing with challenging concepts. For those that are interested---Max at Traxxion Dynamics has a two DVD set called 'Suspension for Mortals' that is well worth the price of admission IMHO. Again, thanks for the post------and much success and fun at the track with your new setup---happy traill kel Quote Link to comment Share on other sites More sharing options...
RC4G Posted January 19, 2010 Share Posted January 19, 2010 Dan is the man and is the only individual I trust with my suspension components. Quote Link to comment Share on other sites More sharing options...
silverbird1100 Posted February 10, 2010 Share Posted February 10, 2010 That's very interesting information, I've been messing aroud with my suspension from day 1 and wish I knew all that back then. Just make sure that when you call him, to take your time and slowly add info to the conversation in a slow and calm manner. I tend to talk fast and get ahead of myself when talking to someone I respect, so he always thought I was a stunter and didn't really have too much time for me. He's awesome though Quote Link to comment Share on other sites More sharing options...
Para045 Posted March 3, 2010 Share Posted March 3, 2010 Quote Link to comment Share on other sites More sharing options...
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