Can someone explain suspension springs to me?

[Z-Rabbit]

I'm still a newer rider, bought my first wheel last July from someone on this very forum! A V12 HT, it's been awesome. The general consensus is that it's a great starter wheel, and I have to agree. That being said, after putting ~900 miles on it, I'm ready to move to something bigger. And more importantly, something with suspension. I get wicked foot pain in a relatively short time, and while I've learned various ways of mitigating that via altering my riding stance/shifting weight/etc., I recently learned that I have a genetic trait--hallux rigidus--in my feet that affects how I stand and exacerbates foot pain. I'm doing stretches and getting orthotics to help, bla bla bla.

ANYWAY. I love my V12, but I want to get a suspension wheel to see if I can extend my time on the pedals before I gotta let my dogs cool off. Plus the idea of having more than 30 miles of range is muy enticing. And going faster than 30 mph without feeling squirrely AF... you get the point. I'm definitely liking the taste of the Lynx kool-aid, but one thing I can't seem to find any information on is the difference between the 3 spring weights: 62, 66, and 70 lbs. Obviously the idea is "heavier riders should get heavier springs". But even people who are considered "heavy riders" (200+ lbs) are saying they love the 62 lb springs, while others say they would only ever consider the 70 lb option.

What I'm asking is: how do I look at this critically? What do the different numbers mean? Is it 62 lbs of force per inch of travel, or millimeter? How do you even measure that with progressive springs? I don't know anything about suspension systems, and I've been reading up where I can, but I still haven't figured this one out. If anyone has some insider info, I'd love to hear your take.

[Whalesmash]

Generally the springs are rated in lb/in. I haven't seen a spring rating with mixed units like lb/mm. There is N/mm, but i have never seen the two mixed together. For the Veteran springs, we aren't given the amount of progression that is built into the springs, so we can only say that the initial part of the travel is rated at whatever it is they listed (62, 66, 70). We also do not know how much that number ramps up to or where within the travel stroke the progression begins to kick in. 

As for what the correct spring rating is for whatever rider should be whatever gives them the correct amount of sag at idle (geared rider standing on top of the wheel). From the MTB world, that number is usually 20-30% of the available travel. There is a lot of personal preference baked into why someone might go higher or lower than their suggested spring rating, but the hydraulic nature of the lynx's suspension covers up a lot of the pitfalls of going too far in either direction. Here's how I would list out the potential extremes:

Heavy rider picks 62lb suspension:

• Idle ride height will be lower 
• Less available compression distance = more likely to bottom out (partially mitigated by good damper adjustments on the lynx and the fact that it has a lot of oil to create progressiveness)
• Softer spring is probably a bit more comfortable

Light rider picks 70lb suspension:

• Idle ride height will be high
• Probably gets some annoying "top out" (again partially mitigated by good dampers)
• More available compression distance
• Harder springs = perceived harsher ride (initial force required to compress the fork will be higher)

 

[Z-Rabbit]

Thank you for such a detailed post! I also had a ride last night with someone who owns a lynx; he's on the heavier side, and he has the 70 lb springs. He said that he feels they're a little stiff for his liking. Between what you said and his input, I think I'm going to look at the 62 or 66 lb option. I don't see myself doing a ton of extreme jumps or anything, but I might want to do the occasional curb bonk, etc. 

[rcgldr]

There are also progressive springs where lb/in increases as spring compresses.

 

[drader]

This is just an educated guess, so I might get some stuff wrong (and this is more based on the Patton than the Linx): I believe the two sides are the same, so you actually have TWO of those springs, so the spring rating would be  (2 X 62) = 124 and (2 X 66) = 132  and  (2 X 70) = 140.  These are pounds per inch. If you weigh 200lb you will compress those options: 1.6" , 1.5" and 1.4". Ok, what is ideal? In the MTB world they tend to aim for 1/3rd sag. IMO if you want to float like a caddy and not do drops aim for 1/2 sag. Also IMO - 85mm is not enough to have your cake and eat it too, I'm guessing we'd need more like 180-200mm travel to really be able to drop off a picnic table and not bottom, while also feeling plush. At 85mm you have 3.3" travel. Honestly the options are not a huge range... I would err on the 70 option, and if you weigh more than 200 DEFINITELY the 70 option.

[Rawnei]

Don't overthink it, follow this chart here to get a spring that correlates to your riding weight and everything will be geat:

 

 

[Planemo]

2 hours ago, drader said:

 In the MTB world they tend to aim for 1/3rd sag. IMO if you want to float like a caddy and not do drops aim for 1/2 sag.

Way too much IMO, I don't know anyone running 50% sag on MTB. 33% max, and thats for hardcore downhill with oodles of travel available to fine tune the curves/play with damping.

I run 25% on my EX30 (95mm travel), 25% on the front of my MTB (180mm travel) and 30% on the rear (160mm travel).

[drader]

I don't know anyone running 1/2 sag on an MTB either... because big drops are expected. But we are talking about EUCs and not everyone is doing jumps. In my experience I just found I vastly preferred 1/2 sag on my T4 for cruising around, mostly on dirt. Rebound travel is often underutilized in suspension systems (this is the ability for the wheel to fill a pothole).  But keep in mind I designed my own linkage and am using a Marzocchi Bomber - I did this to eke out a little more travel, so I have more to spare than normal.

[Planemo]

I do agree with the crux of what you're saying but 25% is usually the best start point and riders can then go from there. But to give you two of my examples:

On my MTB yes I am generally never getting anywhere near full travel unless riding the alps. But its still 'plush enough' even at 25% for riding dirt/general off road. I just don't feel it necessary to adjust air pressures depending on terrain. Part of that is because with 180mm available it's not as critical as most EUC's because even at only 25% I'm sagged 45mm which is nearly half of the available travel on my EX30 (95mm).

On my EX30 I use 25% and find that even on road/trails I can often hit near max travel just going over sleeping policemen, kerb drops or potholes. Yes one could argue that I should maybe consider a higher poundage spring (I'm running 750lb for my 95kg riding weight on stock linkages) but all it will do is reduce comfort and maybe prevent a bottom-out that I will maybe hit once in a blue moon (I don't do drops/knarly off road) so I'm staying with the plush option at 25%. I feel it's perfect for me, giving max travel with the most plush ride with rarely a bottom-out (I think I've had only one in a year of riding).

Theres so many use cases out there that it's a hugely variable thing but in a way I do agree with you. The simple, bottom line is that if you're not hitting bottom out regularly then you can afford to run more sag. But there comes a point when you're sacrificing your remaining available compression travel and on many EUC's there isn't a lot to start with. In your example you're considering the option of running more sag to allow the wheel to rebound into a pot hole (which is an entirely fair statement) but you're sacrificing the amount of compression travel you have left for bumps. I guess it's on the rider as to which way they want to go. I avoid pot-holes like the plague and I nearly always see them so I opt for more compression travel.

Out of interest what total wheel travel do you have with your modded linkages?