I ordered a 100 N spring today and my expectation now is that I will have less dramatic impacts on bumps and road changes due to the ability to put the preload back in the middle of the adjustment.
I meant to ask him about a 200 lb rider and didn't get there.
If someone can help me understand more about the specifics, I still have some gaps in my understanding.
I used to own a garage door company. Garage doors are sprung in 10 lb increments. If you go up 10 lbs over it won't hold the door up, if you go 10 lbs under you can't get it to stay on the floor. Springs are much more precise than you'd ever imagine. The nature of them makes it seem like they'd work over a much larger range. The closer you get to matching your weight the better.
A word of caution. Fast Bike Industries is the USA distributor for Ohlins, Andreani and Nitron. David knows his shit. Skip and Lenny are at K-Tech and they know their shit. The one problem is that these people are working with track performance primarily. They recommend springs that will kill on the track. Not so much on the street. My local performance shop guy knows me, my bike and that I'm strictly a street guy. I want handling but I don't want harshness which the track springs on the street will give you. He warned me that they recommend track springs and that they don't make for a particularly comfortable street bike. He was 100% correct.
I weigh 250 - 260. Initially I went with a K-Tech 35 DDS lite rear shock with a 100 N spring and a K-Tech 100 N spring only (not cartridges). Got them installed and set up. The bike now handled but was harsh as hell. Local guy said I told you so. So then I ordered a 9.5 N spring for shock and forks. (it's easy to change shock springs). Got them changed and went on a ride to NYC and NJ from Massachusetts. Totally transformed the bike. I felt like the front end could be better but stock with the correct springs is pretty good on an MT 10. Now the bike handling was very precise and didn't make every bump a jolt which rattled my body.
Never one to leave well enough alone, I saw Andreani cartridges on sale for $595 back in January. I bought them from Fast Bike. They came from Italy totally wrong. It wasn't Fast Bike's mistake. Having lost confidence with Andreani, I put the $595 towards a set of Ohlins cartridges. They insisted that for my size I need 100 N springs. I argued but they were adamant. I received them and installed them and didn't like them. No better than stock forks with 9.5 springs. 2 weeks ago I ordered a set of Ohlins 9.5N fork springs and installed them this past weekend. I've got almost 300 miles on them and they're substantially better.
My takeaways from the experience. The rear shock is mediocre. I'd go aftermarket before doing an exhaust which sounds good but doesn't give you any additional performance really. The front forks are a lot better than I expected and unless you are a track rider, you can do well with changing just the springs and adjusting oil levels. The rear shock is not all that hard to replace. The front forks take a lot of study and require a shop manual. Not easy but for the more meticulous and adventurous types it;s doable. Hell, I've done them 3 times now. I'm an average rider that pounds it pretty hard most of the time on the street. Not a track guy. If you go the route of good aftermarket shock and cartridges and are a street rider that does some track days, these shocks and cartridges allow for a semi quick spring change and I could see doing that if I was looking to get on the track. The MT 10 is a very rigid frame and is very compliant to whatever you do, but also unforgiving if you don't hit it spot on. Even an average rider will enjoy upgraded suspension. It sneaks up on you and you start having a new confidence and start being able to ride smoother and faster and not get beat up. I felt like I became a much better rider. Having the confidence that you can ride through rough pavement and your bike will stay stable and you can keep it on a precise line and not feel like you're not sure where you're the front wheel is going to end up and your shoulders are going to be dislocated will do that.
I am 250Lbs and a 100N spring was to stiff / harsh for the street even though 2 suspension gurus recommended that size. 9.5 works really well for me on this bike and my previous FJ 09. I had to learn everything the hard way. At 220 pounds, I think it would be a good track set up maybe. Setting the sag / preload sets the ride height, which in turn should put the suspension in pretty much of it's sweet spot with no wasted motion or energy if you have the correct spring weight.
Per my local guy Justin at Adrenaline Cycle, track setup on the street makes for a miserable ride. Tracks are smooth and predictable, streets are not. I didn't listen and it took me over a year to get it right. I'm far from an expert but I now can take a set of MT 10 forks off my bike, completely break them down change cartridges, seals, springs and oil, reinstall, set up and go riding in 1 afternoon. 4th time was a charm. Fortunately I love working on motorcycles almost as much as riding them.
This gels well with my experience as well. I have used Racetech parts in RWU forks on my 90's Suzuki and Hondas, and if I went with their standard recommendations the suspension ended up on the harsh end of compliance on the street. My best front end was on my 1997 VTR1000F which weighs a similar amount to the MT (2kg different stated curb weight), and that had 0.85kg/mm springs which were lighter than recommended, and I also used a lighter compression shim stack. Very compliant and surefooted over bumpy bends. Same happened on my ST1100 which had recommended 1.1kg/mm springs, tried those and swapped down to 0.9 kg/mm which was much, much better.
