[dubjay]

I read another post stating that some bikes don't actually have as much suspension as their marketing departments claim. Especially those that may round up, like...4.25" of travel is marketed as a 5" bike.

So...I got a little curious, and since it was a slow day at the home-office, I set up the following test.

Test Subject: 2006 Chumba Evo - Advertised as a 6" bike

I clamped down the seatpost to my workstand and lowered it so that both wheels would be on the ground.

I stuck a ruler behind the cassette.

With one elbow on top of the seat and a foot on the workstand legs, I pulled up on the rear wheel (after letting the air out of the shock obviously).

I realized that the ruler wasn't straight up and down after I downloaded the pics, so it may be off +/- .125" or so. It looks like it really is a 6 inch bike.

I'll going to do the same thing to my 2004 Specialized Enduro once I get a real wheel put back on there. I have a feeling that one will come up a little short.

 

[Tracerboy]

Curiosity killed the cat....

 

[FireDog46]

or one's enthusiasm

Curiosity killed the cat....

for the bike you find in error.

a little ignorance can be bliss.

michael

 

[womble]

Excellent effort! In hindsight, it's a little surprising that I haven't seen a post like this before. People obsess enough about claimed weights, so why not travel?

I do wonder how accurate travel claims are, and simply assumed that manufacturers were giving accurate figures (especially as some measurements are very specific- 4.2 for a Trance, 5.75 for a Yeti 575).

 

[shiggy]

Do you realize the forks have less vertical travel because to the headtube angle? And the slacker the HTA the less actual travel there is?

 

[womble]

The OP is talking about about rear suspension.

 

[Jayem]

There is a full spread in the MTB world.

First and foremost, pretty much ALL rear shocks, air or coil, have bottomout bumpers. On air shocks they are internal and you can't see them. Under the hardest of impacts, they will compress down to a mm or so, in other words a fraction of the 10-15mm that they usually are, so they don't restrict travel, but you won't be able to compress them unless you can apply 500-700lbs of force.

Cycling the suspension on a stand doesn't work because of the bottomout bumper, and taking the shock out also doesn't really work because you need to measure the correct stroke. It's difficult.

Secondly, some manufacturers count vertical distance, some count "arc length", some give you the actual advertised travel, and some fall short. I have a turner and his bikes are kind of nice because he actually goes a little "over" the advertised travel, so the 6" bikes are 6.125-6.2 and so on, but that is fairly rare. Some bikes like the ellsworth Id would only get 5" when you changed to the "california" edition with the lower BB, but this wasn't advertised and people wondered why their bikes got 5" instead of the claimed 5.5". So, you'll see the entire spread. Generaly most manufacturers are close, but you'll find ones that don't have the claimed travel and occasionally ones that have a little more than the claimed travel.

 

[sonyisdope]

There is a full spread in the MTB world.

First and foremost, pretty much ALL rear shocks, air or coil, have bottomout bumpers. On air shocks they are internal and you can't see them. Under the hardest of impacts, they will compress down to a mm or so, in other words a fraction of the 10-15mm that they usually are, so they don't restrict travel, but you won't be able to compress them unless you can apply 500-700lbs of force.

Cycling the suspension on a stand doesn't work because of the bottomout bumper, and taking the shock out also doesn't really work because you need to measure the correct stroke. It's difficult.

Secondly, some manufacturers count vertical distance, some count "arc length", some give you the actual advertised travel, and some fall short. I have a turner and his bikes are kind of nice because he actually goes a little "over" the advertised travel, so the 6" bikes are 6.125-6.2 and so on, but that is fairly rare. Some bikes like the ellsworth Id would only get 5" when you changed to the "california" edition with the lower BB, but this wasn't advertised and people wondered why their bikes got 5" instead of the claimed 5.5". So, you'll see the entire spread. Generaly most manufacturers are close, but you'll find ones that don't have the claimed travel and occasionally ones that have a little more than the claimed travel.

While I understand what you are saying, and for the most part, I agree with you, I also feel that there should be some standard to test travel.

Dubjay's test, while not the most accurate, can be set as the standard. I mean, who cares about arc travel, or whatever, if we can agree on a standard, then that will be the standard for rear wheel travel.

So, I think that we should agree on the standard that wheel travel is measured straight up and down, and should be measured by standing shock travel.

 

[Ronnie]

You can accurately measure the the frame's designed travel by taking the shock out of the equation which you need to do. I've got a Manitou Swinger which is supposed to have an eye to eye of 190mm. If I measure from bolt hole to bolt hole with the shock fully inflated, it is only about 185mm. The 5mm. translates to 10% of the stroke. If I depressurise the shock it does not stay at the same length, it shortens. I've asked about this and I've been told it has something to do with negative charge.

You need to construct a dummy shock. A piece of PVC pipe is perhaps the best thing to use. Lets say you have a shock with an eye to eye of 190mm. and a stroke of 50mm. Use a piece of pipe that is narrow enough to fit into the shock mounts. Drill two holes at each end 190mm. apart. Then drill a hole 50mm. from one end. You can now measure accurate full stroke travel.

Ronnie.

 

[imridingmybike]

There is a full spread in the MTB world.

First and foremost, pretty much ALL rear shocks, air or coil, have bottomout bumpers. On air shocks they are internal and you can't see them. Under the hardest of impacts, they will compress down to a mm or so, in other words a fraction of the 10-15mm that they usually are, so they don't restrict travel, but you won't be able to compress them unless you can apply 500-700lbs of force.

Cycling the suspension on a stand doesn't work because of the bottomout bumper, and taking the shock out also doesn't really work because you need to measure the correct stroke. It's difficult.

Secondly, some manufacturers count vertical distance, some count "arc length", some give you the actual advertised travel, and some fall short. I have a turner and his bikes are kind of nice because he actually goes a little "over" the advertised travel, so the 6" bikes are 6.125-6.2 and so on, but that is fairly rare. Some bikes like the ellsworth Id would only get 5" when you changed to the "california" edition with the lower BB, but this wasn't advertised and people wondered why their bikes got 5" instead of the claimed 5.5". So, you'll see the entire spread. Generaly most manufacturers are close, but you'll find ones that don't have the claimed travel and occasionally ones that have a little more than the claimed travel.

I'm not sure what the standard should be.

I can see an argument for measuring travel on something other than a vertical trajectory. If a bike's rear wheel moves inline with bump forces - it will move up and back. This is a good thing - if high speed bump absorption is what you're looking for. Depending on the angle though - an 8" travel bike - measuring the total trajectory, may end up appearing significantly less than that if measured on the vertical axis.

The OP showed a valid test - I just have to wonder if this test will work for all the different designs out there.

A battery of tests may be better:

Arc Length (would probably cover what I mentioned above)

Vertical Wheel travel

Difference between the above.

 

[used2Bhard]

Asr-sl

Maybe something was hosed with my bike, but with no air in the shock, and with the shock removed, my ASR-SL got more like 3.1 or 3.25, not 3.9.....

 

[timehoc]

Maybe something was hosed with my bike, but with no air in the shock, and with the shock removed, my ASR-SL got more like 3.1 or 3.25, not 3.9.....

maybe the claimed yeti travel is based on wheel path and not vertical distance.

on my Norco fluid with 5.3" in the rear I was able to get 5" with the vertical distance. I could see 5.3" being plausible via wheel path.