Spring 5 Upgrade Issues

[Apolito Ghosh]

Im currently looking into changing my rear spring and eventually my front. I've kind of lost track of how much weight I've been adding onto my bike and then also realising that the standard spring is so under sprung for the general Western man. I currently have outback motortek x-frame panier racks in the back, alu chain guard, alu oem rally bashplate 4mm, Heed upper crashbars. My rider's weight with full gear is probably close to 92 kg's. I've ridden with this + say 20kg of luggage on trips. Since I progressively added these mods on I find it hard to recall how my bike felt when I purchased it, plus the rally edition already comes heavier than a standard anyway. Because of this I don't exactly know what to expect once I uprate my rear spring. How and where will I feel the difference if I go to say a 90nm spring?

I got K-tech springs and valves fitted, exact values are in my topic called "full K-tech suspenssion upgrade". Contacted suspenssion specialist with my weight in kit and full weight of bike ugrades and he choosed spring rates.

But i can tell you comfort o tarmac has decreased significantly. Its now great offroad on faster sections and jumps, slightly to stiff on wet offroad as i prefer softer setup for mud (better grip) but on tarmac its just less comfortable and at he beginning it was even annoing... now i got used to it, but sometimes on tarmac i do miss this stock undersprung suspension that makes you feel like you riding a couch

For me updating the spring meant that rear suspension isn't that harsh. I actually became more plush. This might seem quite counter intuitive, but when you start to think about physics it starts to make more sense.

T7 has progressive rear linkage. What it means is that there is a mechanical system that will make the spring behave like it's progressive. If you have too much rider sag it will mean that progression gets "eaten up" and first part of the progression is already used and suspension starts from a relatively high progression rate. That translates to harshness because 1mm upwards motion will require more force (because relative spring rate will be bigger because of progressive nature of linkage).

For me stiffer spring on back ment less harshness on- and offroad. I was actually quite surprised about the difference in comfort increase. Especially with my travel gear on. I went on with compromise spring. Tad too stiff for me alone, slightly undersprung with my travel gear. Nothing some preload can fix though.

Steering is slightly more calm because of negligible change in rake. This is more prominent in hard braking and steering in. Overall it's slightly more firmer and there is slight improvement on braking and overall firmness. No night and day stuff. Just slight overall stuff. Although I have to say I did add some preload to my front before actually updating my front springs, so I have no direct comparison between stock vs. updated.

Things @Bartek describes in his post are IMO more likely to be result of complete suspension upgrade. On my experience upgraded shocks almost always result to drop in overall comfort. especially when optimized to offroad. Upgraded shocks tend to track better so you feel every bump under the wheels. When you are pushing your bike, this is information you need to know but when touring, this constant reporting on every single crack on a pavement can be quite tiresome.

I found this swingarm progressiveness largerly overrated. Riding it back to back with other bikes wih PDS suspension i canot see any benefits. I think yamaha employ some marketing to cover up for rubbish quality stock shock But that's just my opinion.

@witgenThanks for the nice write up. I'm also curious to your spring values. What is your experience with the changes you made to the front pre load? I haven't touched them yet myself but I do find that my front dives too much, especially during braking.

Good question. I have to check this out. I'm fairly certain I have 95N/mm spring on back and 6.6 N/mm on front. I weigh roughly 110kg and my touring gear is around 25kg. Sag is about 55mm with my riding gear on and I weigh about 110kg.

Although I think it is not comparable to stock bike. I have a custom seat, custom foot pegs and custom handlebar and I have a seating position that is different from stock. So it changes the geometry somewhat. How much it does that, I have no idea.

It's good to point out that for example KTM uses progressive shocks that do similar things than progressive linkage. So difference isn't that obvious. To be honest I think PDS is superior over progressive linkage as long as you have good progressive shock. But we are splitting hairs here. Fact is that there is way too much sag with stock springs and that does add harshness to rear suspension. If I was 25kg lighter I would probably only notice the fact that rear suspension is slightly firmer on big bumbs. But I have no reference point so I'm basically guessing here.

And I don't think T7 has a rubbish rear shock. It's just not optimized for offroad. It's more like compromise shock emphasis on non-offroad riding. Interestingly almost everybody thinks T7 is better on road than 790/890. I wonder why that is. Is it because Yamaha engineers just don't know how to tune suspension and geometry to work off road? Or maybe they knew all along that they will be making World Raid version with proper off road suspension and the goal for base version was to appeal to wider audience even though it meant using more street oriented parts...

Front springs don't have preload adjustment. I made my own adjustment blocks out of aluminium. I think most riders could actually skip front spring upgrade with these. Only problem is that if you don't have tools to make your own preload blocks, it's probably cheaper to buy new springs than it is to get someone do those for you.

Diving is a trade off for long stroke soft suspension usually used in adventure bikes. You cannot solve diving issues with stiffer springs. It's more of problem handled by low speed damping, but adding that creates other issues. There is a reason we have so many anti-dive solutions in forks. You also cannot actually adjust low speed damping in Tenere unless you revalve the suspension or get fully adjustable shocks.

Suspension is always a collection of compromises. Address one issue and you have a set of new issues. I think T7 suspension is wonderfully balanced between on/off road driving still maintaining relatively good touring capabilities. And that's quite a feat to achieve that. If you want offroad machine for technical off road driving, well... You want a supermoto, well... you want jack of all trades mediocre on everything? Bingo!

I also seen in videos that the spacers can help with a lot, that the stock front sag is actually pretty damn bad as well. I like having a jack of all trades, it's something you gotta learn to live with on the t7, it grows on you as well I feel. Knowing I can be alright to good in almost every scenario.

@witgen I'm not sure what you are referring to saying KTM uses progressive shocks... shock absorbers can be valved differently, but they will also behave linear, as shimms will flow oil through at even velocity at every part of the stroke. Only springs can be progressive, and they are not good offroad as they are diffcult to "feel" by demanding riders.

But it's worth mentioning i have come directly from WP CS4 with 280mm travel on 701 Enduro, and this was best suspension i have come across on dual sport bike - it could be set up softer for tarmac riding and it won't still bottom out when pushed offroad on massive jumps thanks to long travel. It is impossible phisically to achieve this with 210mm travel.

I cannot compare Tenere tarmac traction to 790/890, as i only ridden one offorad, but can compare to 990ADV, and Tenere is better round the twisties, but this is down to geometry in my opinion- rake, wheelbase, swingarm angle to main sprocket ect. T7 is brillant, 990 just feel long and sluggish compare to T7. On other hand 701 feels too light and past 100mph you just about to get airborne

To sum this up - it all depands from everyone's subjective feeling - I'm 101kg , have 85Nm spring on the back, compression damping set to minimum (within technical reasonability) and complainin it's hard on the road... While Withen is only 9kg heavier, got 95Nm spring and saying bike get more comfy.

high speed offroad it was actually not bad...until you hit some surprise little bump, and you are quickly reminded this isn't a tuned DRZ anymore. It also feels practically unrideable with a 130lb passenger....Although I guess to be expected.

I was considering an 85 rear spring, and 6.6 fork springs (currently reading into heavier oil as well?), to just compensate for the addons and get it back to the mentioned "jack of all trades". I talked to a few of the suspension companies and they all were different in their suggestions. So back to the drawing board.

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