Links: Good or Bad?

[BLZ2DWL]

I've read all sort of opinions over the years about lowering links and their impact on leverage ratios, etc. However, I'm not convinced they apply to the T7. From the shock's perspective, how does it know you have lowering links? The pivot point on the swingarm and the location of the linkage attachment are fixed, so the swingarm is exerting the same force through the link no matter how long it is. It would be different if you were moving the location where the link attaches to the swingarm.

 

When I look at the T7 specifically, a longer link simply moves the swingarm and wheel up closer to the bike, within the same stroke as the stock link. It would appear to me that the wheel is just already closer to the frame, but nothing about how the shock works has changed. It would certainly change the leverage ratio if the bellcrank (or whatever you call the piece that attaches to the shock) lengths were adjusted, but the lowering links seem to simply exert forward or rearward pressure. They aren't really rotating (example of short or long wrench does not apply). 

 

I also hear "use an internal lowering spacer to maintain stock operation", but doesn't an internal spacer simply mean you are starting part way through the shock's stroke? You are essentially limiting how much the shock can extend, meaning you have shifted the entire stroke of the shock. How is that good? 

 

Long story short: I am 105kg and need to both lower the bike a bit and fit a higher rated spring. I was considering the 90NM spring, but RR says to go up if you are running lowering links. I just don't understand why longer links change the leverage. I'd love to be convinced otherwise. 

Edited December 20, 2020 by BLZ2DWL

[MGG]

7 hours ago, BLZ2DWL said:

I've read all sort of opinions over the years about lowering links and their impact on leverage ratios, etc. However, I'm not convinced they apply to the T7. From the shock's perspective, how does it know you have lowering links? The pivot point on the swingarm and the location of the linkage attachment are fixed, so the swingarm is exerting the same force through the link no matter how long it is. It would be different if you were moving the location where the link attaches to the swingarm.

 

When I look at the T7 specifically, a longer link simply moves the swingarm and wheel up closer to the bike, within the same stroke as the stock link. It would appear to me that the wheel is just already closer to the frame, but nothing about how the shock works has changed. It would certainly change the leverage ratio if the bellcrank (or whatever you call the piece that attaches to the shock) lengths were adjusted, but the lowering links seem to simply exert forward or rearward pressure. They aren't really rotating (example of short or long wrench does not apply). 

 

I also hear "use an internal lowering spacer to maintain stock operation", but doesn't an internal spacer simply mean you are starting part way through the shock's stroke? You are essentially limiting how much the shock can extend, meaning you have shifted the entire stroke of the shock. How is that good? 

 

Long story short: I am 105kg and need to both lower the bike a bit and fit a higher rated spring. I was considering the 90NM spring, but RR says to go up if you are running lowering links. I just don't understand why longer links change the leverage. I'd love to be convinced otherwise. 

...I have 20mm lowering links ... with 90NM spring ... I am around the 100kg and to get the sag right I had to go to 10clicks on the preload. With camping gear I go all out and it's excellent. If I was to do it all again I would go to 95NM just because it's more, but at the same time if I eat a bit less during winter I will be glad the 90NM is on  

Keep in mind that the behaviour of the rear pivots creates the equivalent of a progressive spring. So if you compress the suspension by the equivalent of 20mm travel (the lowering links), then the spring needed would have to be a bit stronger to compensate for the normally compressed sprint at that position. So I think that it makes sense what RR tells us. How much, that is up in the air at the moment. That is just my understanding.