Front fork travel

[viewdvb]

The front fork travel is listed at 190mm. I have put a thin tie wrap on mine to check travel and it has NEVER travelled more than 150mm even two up, fully loaded and braking for downhill hairpins. I have the preload at about 2 rings harder than stock, which is a very few millimeters difference, to provide acceptable loaded sag. Does this match other riders' experience? So what use is the extra 40mm travel? I notice that Racetech recommend a slightly harder spring which would not help to increase travel and that other contributors who have changed the spring have ended up with roughly the same as OEM but linear, not progressive like OEM, so that wouldn't help. I considered the recommended oil height of 150mm being restrictive but discovered that this is set with the forks fully compressed so shouldn't prevent the travel. Anyone got any suggestions about what restricts the travel to only 150mm out of 190mm and how to increase it?

 

[greg the pole]

Not sure if I can help shed light on this, as my suspension lingo is limited, but I have been tooling on my own stuff for a bit, and I'm a fast lerner )
On stock factory settings, stock oil (10w) I found the bike a bit harsh on initial compression. I tried backing out the preload, and compression damping, but it didn't seem to help.
This winter I took the forks apart, cleaned them (dampner assmeblies included), refilled them to 150mm each, but with lighter oil (7.5W)
Since i'm in the frozen tundra, I have not had a chance to try it out. I will start with factory setting, and make small changes from there.

 

[avc8130]

The front fork travel is listed at 190mm. I have put a thin tie wrap on mine to check travel and it has NEVER travelled more than 150mm even two up, fully loaded and braking for downhill hairpins. I have the preload at about 2 rings harder than stock, which is a very few millimeters difference, to provide acceptable loaded sag. Does this match other riders' experience? So what use is the extra 40mm travel? I notice that Racetech recommend a slightly harder spring which would not help to increase travel and that other contributors who have changed the spring have ended up with roughly the same as OEM but linear, not progressive like OEM, so that wouldn't help. I considered the recommended oil height of 150mm being restrictive but discovered that this is set with the forks fully compressed so shouldn't prevent the travel. Anyone got any suggestions about what restricts the travel to only 150mm out of 190mm and how to increase it?

The stock spring is NOT progressive. It is dual rate. There is a big functional difference.

A progressive spring will have a rate that increases as the spring compresses. The stock springs have 2 rates: ~.85 and ~1.1. The ~.85 is used to set preload and provide some small bump compliance. The 1.1 is around for the heavier hits.

This dual rate makes the stock front feel "harsh" and "wallow" as most riders are on the verge between the rate shift. This means the forks is constantly traveling between rates and this generally sucks.

The stock spring is actually quite stiff in the functional rate. Most suspension tuners suggest rates that are softer than this.

I would definitely suggest you talk to a suspension tuner. Nick at Stoltec Moto has extensive knowledge with the Tenere (sales@stoltecmoto.com). Jaxon at Ride On ADV is getting into the Tenere suspension realm too (sorry, I don't know his email).

ac

 

[mcrider007]

To answer the question that was asked, the listed travel is usually the total possible travel without springs or oil. However, the last thing you want to happen is metal to metal contact so the tubes have internal top out springs to give the rebound valving piston a soft landing when the forks are fully extended and a oil lock that creates a hydraulic lockup at the bottom of the forks during the compression stroke.

 

[Rasher]

The stock spring is actually quite stiff in the functional rate. Most suspension tuners suggest rates that are softer than this.

MCT is not far from you, they told me the sag used up most the soft part of the travel and made it quite harsh for road use, as I don't plan on anything other than the gentlest of offroad use they fitted linear springs (0.9 I think) and now it rides far smoother and I use most the travel now. They also told me it has bugger all damping and put much heavier oil in.

Posted more details elsewhere, but basically it feels far nicer now and despite softer springs the dive feels better (probably slowed down by the extra damping) costs about £200 ride-in ride out including parts, setup and advice.

 

[viewdvb]

Sorry guys - to cure any misunderstanding - I am not commenting on the ride quality or how to improve it. Just that my forks NEVER seem to use the quoted available travel, even with very heavy loads and hard braking. I take mcrider007's point. Of course they are set up to not hit a metal to metal bottom but that doesn't use up 40mm. I reckon the final hydraulic bump stop might be expected to use no more than 10mm. So what about the other 30mm lost travel. I can't believe that any designer could specify 190mm of travel and not expect to use most of it under some riding circumstances yet that is exactly what my measurements of the travel are telling me.

Racetech list the stock springs as .96 Kg/mm (53lb/in). They do not mention dual rate so it is not clear which of the dual rates they may be specifying or whether they are calculating some combination of the two. Their recommended single rate replacement is slightly stronger at 1.034 Kg/mm. The MCT recommendation as Rasher told me was .95 which is almost exactly what Racetech say is the stock rate. If Racetech are right, I cannot see how either of these spring changes would result in a greater fork travel. Nor can I see how using 10wt oil (the OEM is 5wt Greg) for greater/better damping will result in greater fork travel. Remember, I am not concerned with ride quality, just interested in making the full travel available.
You say you are using most of the travel now, Rasher, but is that a riding impression or have you measured it in some way?
Quite right, AC, multirate is not the same as dual rate. Forgive my sloppy terminology. Tell me - where did your spring rate numbers come from and what units are they measured in? Without specifying the units, I cannot evaluate your comments.

So.... no obvious pointers so far but I welcome every comment.

 

[Firefight911]

viewdvb,

Look up my topics on suspension. I have completely changed both front and rear. I'm in iPhone so can't link them for you. Just look up my profile and posts by topic and they'll pull right up.

The front are dual rate springs, not progressive rate. My swap to linear rate springs with oil swap and proper set up for my use provides me with full travel.




Sent from my iPhone using Tapatalk which means there are more than likely spelling errors!

 

[Rasher]

Look in the owners manual - it gives the stock rates :exclaim:

I (as others) have seen the springs and they are indeed dual rate, MCT measured mine whilst I was there as they never trust manuals and check for themselves, they agreed the manual figures were about right.

I can't believe that any designer could specify 190mm of travel and not expect to use most of it under some riding circumstances yet that is exactly what my measurements of the travel are telling me.

Have you tried a 6 foot jump yet :question: or this:-

http://www.youtube.com/watch?feature=player_embedded&v=bdEh3kEagZY#t=10s

I bet he had less than 40mm spare :exclaim: Check out around 1:50 - big air ::013::

 

[snakebitten]

Look in the owners manual - it gives the stock rates :exclaim:

I (as others) have seen the springs and they are indeed dual rate, MCT measured mine whilst I was there as they never trust manuals and check for themselves, they agreed the manual figures were about right.

Have you tried a 6 foot jump yet :question: or this:-

http://www.youtube.com/watch?feature=player_embedded&v=bdEh3kEagZY#t=10s

I bet he had less than 40mm spare :exclaim: Check out around 1:50 - big air ::013::

That's a BIG boy on the Blue Beast.
Obviously has no use for ABS or TC.
I bow.

 

[avc8130]

That's a BIG boy on the Blue Beast.
Obviously has no use for ABS or TC.
I bow.

Wow, with how he uses a tire he would NEED a K60 just to get to the corner store with enough tread to ride back home...maybe!

ac

 

[viewdvb]

Thanks for the pointer, Rasher. The factory information is always a good start. It's in the Workshop Manual, by the way, not the Owners Manual.