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Old 09-22-2009, 03:36 PM   #1
YetiGS OP
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F800GS Fork springs/kit for a 215 lb. rider

I've read through all the threads here and frnkaly my head is spinning and I can't seem to find a direct answer to my question. So here it is:

What fork springs should I get and where can I get them?


Oh, you need details?? Ok. I weigh ~215 and probably 230 with gear. I like to ride off-road as much as possible.

Last weekend I did a ride that I wouldn't call technical (at least for a "real" dirt bike) but it was rutted and rocky dual track. 4 or 5 times I bottomed out the forks on ruts crossing the trail, one hit was HARD. I clearly need firmer springs.

I've read about the Bitubo kit, looked at the Hyperpro springs, etc. and none of those look like they're appropriate for someone my weight. Someone my weight has the Hyperpros and said that they were a big improvement but that he still bottomed them out.

I really like the idea of the Bitubo kit since the forks could really use a lot less compression damping, but it seemed to me that they only come with one weight of spring. Am I wrong?

Thanks in advance.
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Old 09-22-2009, 04:32 PM   #2
Ducksbane
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Hyperpro Springs

I don't know about the Bitubo Kit ... too expensive, but I am about your weight and have the Hyperpro Springs.

I probably don't ride as hard off the bitumen as you do, but I think the Hyperpro's are a big improvement. I used to hate how the stock forks would bounce off things rather than absorbing them. I haven't had time to change the fork oil, but I am much happier with the forks. They don't bottom as easily and the other day I finally got some air on the 800 coming out of a causeway at about 90 - 100km/hour. On landing the forks were good and progressive, but the stock rear end (which feels a bit firm on small bumps) felt very soft and unprogressive. ITSATDM says the rear hyperpro makes a bigger difference than the front, I suspect that he's right.

Even with the front progressive springs the 800 suspension isn't really plush, but I think it helps make up for BMW making it a bit too road orientated and not progressive enough. (Also cheap) Personally, I am now reasonably happy with the front, and I suspect that when I change the oil in the forks and get the rear spring it will be good enough for my needs.

I guess that if you have the money to spend you should get the Bitubos and a rear hyperpro shock, otherwise front and rear progressive springs will help.
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Old 09-22-2009, 04:40 PM   #3
YetiGS OP
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Thanks. I just wish Hyperpro made a slightly heavier weight spring.


I spoke with Mark at Precision Concepts here and he said he could do something for me if I can tell him the outside diameter and free length of the stock spring, the stock spring rate and the spacer length (if any).

Anyone know this info?
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Old 09-22-2009, 04:48 PM   #4
johngil
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I weigh what you do and couldn't be happier w/ the Bitubo kit.
Bike has frequent off road use. You are welcome to ride my bike, but we aren't exactly close by.
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Old 09-22-2009, 05:03 PM   #5
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Quote:
Originally Posted by johngil
I weigh what you do and couldn't be happier w/ the Bitubo kit.
Bike has frequent off road use. You are welcome to ride my bike, but we aren't exactly close by.
Did you get a heavier weight spring or tell them your weight when ordering? Maybe there is a heavier spring option then.
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Old 09-22-2009, 05:13 PM   #6
johngil
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It comes w/ a 6.0. Seems to work well for me. I measured the springs when I got the kit thinking I would need heavier, but haven't needed to.
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Old 09-22-2009, 05:15 PM   #7
itsatdm
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I saw on one of the threads, an inmate saying that Hyperpro did make a heavier version of the Hyperpro spring. The spring weights I have seen quoted for the stock spring was something like .46. The regular Hyperpro spring weight range is .52-.73, that is a substantial difference and should be adequate for your weight. I am surprised that someone bottomed one out, they must be fairly heavy.
The Hyperpro is a true variable rate spring. Each coil is incrementally closer or further from the next, unlike some that claim to be progressive. A heavier rider may collapse a coil or two making them dead, but at the same time the spring is made shorter and getting into a heavier part of the spring, both increase spring weight. I found at 200#, I had to shorten the spacer to get proper sag. You can easily go the other way.
For reference, the spring rate in the Bitubo unit .62 straight wound and is supposed to good for up to 100kg, I have not bottomed that unit either, but I am old and slow. Repringing should not be a problem either, but I DNK what effect that may have on valving and that is heart of the unit.
As for the rear, I DNK the spring weight for the Hyperpro but it must be way more than stock. Even with no preload it will raise the rear a couple of inches. Coupled with Bitubo unit, I see no need to go aftermarket on the rear.

itsatdm screwed with this post 09-22-2009 at 10:33 PM
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Old 09-22-2009, 07:08 PM   #8
YetiGS OP
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Quote:
Originally Posted by itsatdm
I saw on one of the threads, an inmate saying that Hyperpro did make a heavier version of the Hyperpro spring. The spring weights I have seen quoted for the stock spring was something like .46. The regular Hyperpro spring weight range is .52-.73, that is a substantial difference and should be adequate for your weight. I am surprised that someone bottomed one out, they must be fairly heavy.
The Hyperpro is a true variable rate spring. Each coil is incrementally closer or further from the next, unlike some that claim to be progressive. A heavier rider may collapse a coil or two making them dead, but at the same time the spring is made shorter and getting into a heavier part of the spring, both increase spring weight. I found at 200#, I had to shorten the spacer to get proper sag. You can easily go the other way.
For reference, the spring rate in the Bitubo unit .62 straight wound and is supposed to good for up to 100kg, I have not bottomed that unit either, but I am old and slow. Repringing that spring should not be a problem either, but I DNK what effect that may have on valving and that is heart of the unit.
As for the rear, I DNK the spring weight for the Hyperpro but it must be way more than stock. Even with no preload it will raise the rear a couple of inches. Coupled with Bitubo unit, I see no need to go aftermarket on the rear.
So do you have the Bitubo or Hyperpro in your fork?

And, since you've mentioned it, how did you get the Hyperpro spring on your rear shock? Surprisingly, the Hyperpro kit from Touratech seems like a really good deal. I'm just not sure how I'd get the rear spring done...
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Old 09-22-2009, 07:19 PM   #9
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Had the Hyperpro, found it fine for pavement and smooth dirt. Went to the Bitubo because no spring or fork oil was sufficient to deal with sharp edge off road stuff like rocks.
You need a spring compressor for the rear spring. The preload stuff just slips off once the spring is out. I could not find a spring compressor so I just lashed up some short pieces of angle iron and 4 6in. carriage bolts and made my own. Needed 4 hose clamps to keep if from slipping off the springs
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