|04-23-2011, 03:17 PM||#1|
Joined: Sep 2007
Location: Columbiana County, OH
Project WeeStrom 7.5
What Is It?
A 2004 DL650 with 7.5 inches of front and rear suspension travel, and 7.5 inches of ground clearance.
What I Did
I modified the damper rods of my front forks to gain 40mm of front suspension travel, and to increase the ride height. My front ride height increase is actually 27mm over stock, with the proper rider sag dialed in and accounting for the rake of the chassis. Custom springs and spacers were necessary to achieve the proper sag. I also have “widgets” installed in the forks, which basically act like emulators to control damping. These have no influence on ride height or overall suspension travel though.
Stock Fork, Full Compression Travel Measured:
Modified Fork, Full Compression Travel Measured:
Modified Forks Installed:
I also raised the rear of the bike with a custom made longer travel shock from Cogent Dynamics. This shock provides 41mm more travel than stock. The actual rear ride height increase with me in the saddle is 29mm with the suspension sag set correctly, which maintains the bike’s handling balance.
This Cogent shock is a premium unit. The shock uses a stiffer spring to obtain the proper sag numbers for my 225 lb weight. For damping, this shock has a remote reservoir with high and low speed compression adjustments, and adjustable rebound near the lower clevis. Rick made the shock with a 46mm body and a 16mm shaft (stock is 40mm and 14mm, respectively). This allows for a greater volume of fluid, therefore providing performance consistency and more accurate adjustability. The shock body and reservoir are both aluminum, which further aids in heat dissipation (the stock shock is steel, and is an emulsion type, with no piston to separate the fluid from the nitrogen).
Custom Cogent Shock Vs Stock Shock with aftermarket spring
Why I Did This
There are 2 major short comings of the DL650 when it comes to rough road/ offroad capabilities: limited ground clearance and limited suspension travel. I want to be able to ride this bike on basically any non-maintained dirt road and not have to worry about getting high-centered. I also want a plusher ride, but with bottoming resistance.
Stock DL650 High-Centered on a trail ride last year
I know the DL is not a dirtbike and I’m not trying to make it into one. I have a couple other bikes for real trail riding. I’m simply trying to improve it to the capabilities of the other adventure bikes out there, such as the Super Tenere, the GS1200, or the new Tiger 800. I know my modified bike’s offroad capabilities fall short of the benchmarks: the KTM 950/990 Adventure and the F800GS. However, those bikes have some reliability issues and price tags that I’m not willing to deal with, and I probably don’t need that much offroad ability for what I do with my Strom. FWIW, I used to own a 950 Adventure.
If you just ride on pavement most of the time, 5-6 inches of travel is all you really need, as it keeps the center of gravity low and minimizes chassis pitch during acceleration and braking, while absorbing most small bumps. Now start taking that bike on beat up roads and the forks/shock will quickly blow through the stroke and bottom out if you weigh over 160 lbs. If you’ve ever bottomed the suspension, you know it is neither pleasant nor safe. Even if you don’t bottom all the way, the last 20mm of travel are rather “firm”, since there is an oil lock piece in the bottom of the fork tube that quickly increases the resistance to travel. It’s like pulling your parachute in a free fall (it’s better than hitting a wall). I’ve bottomed out the stock suspension (preload maxed out) on just beat-up “maintained” roads and potholes, using all 135mm of compression travel.
So the typical thing to do is install stiffer springs (30% higher rate than stock in my case) and heavier fork oil, and maybe emulators (I did all the above). Now the suspension is less likely to bottom out, which is good. Those same roads that used 135mm of compression travel, now only use 120mm of travel and we are almost out of the dreaded oil lock territory. However, we now have to deal with less compliance (i.e., plushness) over all the smaller impacts. Simply put, the suspension now moves less and the chassis moves more. Not a great compromise for comfort or traction, but better than stock in most people’s opinions (mine included).
With the 40mm increase in travel, I was able to lower the spring rate by 10-20% because there is more travel in the suspension before it will bottom out. Yes, it will still eventually bottom out, but all the impacts up until bottoming cause less chassis movement and better tire contact with the surface, resulting in better comfort and traction. Those same roads that used 135mm of travel with the stock springs and 120mm with the stiffer setup, now use 130mm of travel (the spring rate is 10% stiffer than stock in my case). Another big difference compared to the stock suspension is my bike stays out of the oil lock territory longer, so even the bigger impacts are nicely absorbed by the suspension (no parachute effect).
'11 KTM 250 XC (dual sported)
'05 KTM 450 EXC (dual sported)
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