How to measure travel on coil shock?

[teK--]

So can anyone offer advice on how to reliably measure the amount of travel being used in a coil shock?

Sag is no issue this is easy to measure the E2E, but I want to know how much maximum travel is being used.

Sliding the bump stop up to the damper body doesn't work, because it is 8mm thick and this makes up 14% of the shock's travel. How would I know if I was merely touching the bump stop or near bottoming out to within a millimeter of its life?

Cheers.

 

[The Duckmeister]

Can you get in a put a small cable tie around the damper shaft?

 

[teK--]

Can you get in a put a small cable tie around the damper shaft?

Yeah I could but if I hit the bumper or bottom out then the zip tie will just get crushed up against the wiper seal which wouldn't be pretty... Or it would get squashed into the bump stop which doesn't give a good idea of what amount of travel was used.

 

[Zaf]

Two P-Clips with some wooden dowell attached to each eyelet part of the hardware. Secure one side firmly so it moves with the linkage, and the other P-clip to simply guides it's path. On the wooden dowel you can mark out measurements, and then simply use a rubber o-ring or subsitute that gets pushed down the shaft by the second static P-clip on compression. If the o-ring reaches a measurement point indicative of your shocks stroke length, you've achieved full travel.

 

[teK--]

Two P-Clips with some wooden dowell attached to each eyelet part of the hardware. Secure one side firmly so it moves with the linkage, and the other P-clip to simply guides it's path. On the wooden dowel you can mark out measurements, and then simply use a rubber o-ring or subsitute that gets pushed down the shaft by the second static P-clip on compression. If the o-ring reaches a measurement point indicative of your shocks stroke length, you've achieved full travel.

Thanks I thought of that but the lower eyelet is deep in the frame so cannot really attach anything to it.

My initial idea is the same as yours, to replicate the commercially available types like this:



But there is no where up top to attach it to. So i was thinking of making up a plate that sits between the spring each of the two collars like my povo paintshop drawing:


Anyone got a 3D printer or laser cutter? :laugh:

 

[Markee]

Instead of a cable tie on the shaft try a small length of elasticised cotton tied around it. It won't do any damage if bottomed out then.

 

[Nautonier]

You read my mind, I've been thinking about the exact same issue. What happens inside the bottom out bumper is a significant part of the shock's travel and needs to be measured accurately. For all I know I'm bottoming out my 400lb spring way more often than I should be.

I've thought of removing the bumper and using the cable tie method, but it will be harsh on the shock when I do bottom out and could cause damage.

What shock are you using by the way? You're on a 6" bike aren't you?

 

[Nautonier]

Instead of a cable tie on the shaft try a small length of elasticised cotton tied around it. It won't do any damage if bottomed out then.

Yes, but it will stop at the top of the bumper and not measure that part of the travel.

 

[teK--]

You read my mind, I've been thinking about the exact same issue. What happens inside the bottom out bumper is a significant part of the shock's travel and needs to be measured accurately. For all I know I'm bottoming out my 400lb spring way more often than I should be.

I've thought of removing the bumper and using the cable tie method, but it will be harsh on the shock when I do bottom out and could cause damage.

What shock are you using by the way? You're on a 6" bike aren't you?

That's right in my case the bumpstop makes up the final 8mm of shock travel which equates to roughly 20-22mm of the 160mm wheel travel in that part of the stroke..

Quite significant amount and important to get the shock settings right, since the frame leverage curve goes from slightly progressive to linear then slightly regressive during that final part of the stroke.

I have searched high and low and not found much discussion on this topic, nor suggestions other than just to go by feel (or strap a spoke/dowel into the side as suggested above)

Shock is CC DBIL coil.

 

[Nautonier]

That's right in my case the bumpstop makes up the final 8mm of shock travel which equates to roughly 20-22mm of the 160mm wheel travel in that part of the stroke..

Quite significant amount and important to get the shock settings right, since the frame leverage curve goes from slightly progressive to linear then slightly regressive during that final part of the stroke.

I have searched high and low and not found much discussion on this topic, nor suggestions other than just to go by feel (or strap a spoke/dowel into the side as suggested above)

Shock is CC DBIL coil.

I have the same shock and the CC calculator has put me between a 350 and 400lb spring, I opted for the 400. Whilst the shock feels great, I have noticed that if I use the bumper to measure travel, it moves very quickly to the bottom of the shaft, which is where measurement becomes impossible. It doesn't feel like it bottoms out harshly, but with a bumper and quite a lot of HSC it probably wouldn't. Like yourself, I'd prefer to know for sure what's happening during that last 8mm of stroke, so will be watching this thread with interest.

I'm about 75kg kitted up and on a Range. I also tried a 350 spring and it didn't feel terrible, I'd like to also try a 450 to see what that feels like. If you need a 350 or 400 to try I have both spare assuming you're on a 2.5 stroke.


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[Zaf]

I have the same shock and the CC calculator has put me between a 350 and 400lb spring, I opted for the 400. Whilst the shock feels great, I have noticed that if I use the bumper to measure travel, it moves very quickly to the bottom of the shaft, which is where measurement becomes impossible. It doesn't feel like it bottoms out harshly, but with a bumper and quite a lot of HSC it probably wouldn't. Like yourself, I'd prefer to know for sure what's happening during that last 8mm of stroke, so will be watching this thread with interest.

I'm about 75kg kitted up and on a Range. I also tried a 350 spring and it didn't feel terrible, I'd like to also try a 450 to see what that feels like. If you need a 350 or 400 to try I have both spare assuming you're on a 2.5 stroke.


Sent from my iPhone using Tapatalk

Got a go pro that you can mount pointed at the shock and then review? That's another way of going about it.

 

[Nautonier]

Got a go pro that you can mount pointed at the shock and then review? That's another way of going about it.

A Gopro shooting at 240 fps and then slowed down would be an awesome way of seeing what's going on, especially if it was synced with another camera showing the trail features so you could see how various jumps, drops, berms and g-outs affected the suspension characteristics. Surely pro suspension tuners have thought of this?

 

[teK--]

A Gopro shooting at 240 fps and then slowed down would be an awesome way of seeing what's going on, especially if it was synced with another camera showing the trail features so you could see how various jumps, drops, berms and g-outs affected the suspension characteristics. Surely pro suspension tuners have thought of this?

Andrextr has already thought of that... and there is free software that can give you some pseudo-telemetry as well:

https://www.youtube.com/watch?v=4BRbtkiW2tg&t=1s

I suppose key would be to locate the camera sufficiently so you don't get too much parallax error.

 

[teK--]

I have the same shock and the CC calculator has put me between a 350 and 400lb spring, I opted for the 400. Whilst the shock feels great, I have noticed that if I use the bumper to measure travel, it moves very quickly to the bottom of the shaft, which is where measurement becomes impossible. It doesn't feel like it bottoms out harshly, but with a bumper and quite a lot of HSC it probably wouldn't. Like yourself, I'd prefer to know for sure what's happening during that last 8mm of stroke, so will be watching this thread with interest.

I'm about 75kg kitted up and on a Range. I also tried a 350 spring and it didn't feel terrible, I'd like to also try a 450 to see what that feels like. If you need a 350 or 400 to try I have both spare assuming you're on a 2.5 stroke.


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Mine calculated 420lb for 30% sag, so I took a 450 spring which gives 27% sag with 1 turn preload. Happy with that. Note our frame ratios are different.

Since you used the same calculator you probably have the correct spring and I think 450 would be too firm. Maybe go for a 425lb if you can afford the fancy springs that come in those increments?