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Old 05-04-08, 05:21 PM   #1
jrtozer
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Front and Rear suspension bottoming on Downtube FS

Hi Folks,
I have a 2007 Downtube FS 9 folder that I am still getting dialed in. I've noticed while riding that the rear suspension coil spring is completely compressed when I'm riding (I weigh 210lbs). It appears that the pre-load is adjustable by turning the metal disk, but that wouldn't help me (right?). Any ideas about how to add more spring?

Also, the front suspension is also bottomed out while riding. Is there a source for stronger elastomers or something? Does anyone know if the new Zoom Transarch fork upgrade is stronger (I know it has adjustable pre-load, but again, that's not the problem, right?)?

Thanks,
-J.R.
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Old 05-04-08, 05:37 PM   #2
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You are correct - setting pre-load won't change the spring constant. The only remedy is to get a stiffer spring. Where to get those - I suppose the LBS is a good place to start.
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Old 05-07-08, 04:32 PM   #3
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You are correct - setting pre-load won't change the spring constant. The only remedy is to get a stiffer spring. Where to get those - I suppose the LBS is a good place to start.
Well my LBS isn't much for custom stuff, but I did find a few sources of springs online. Surprisingly, it seems like the OEM spring is a pretty strong spring - it is marked as 850 lbs/in, which is higher than any aftermarket spring I could find (usually in the 3-500 lbs/in range). Also, I cannot seem to get the OEM spring off the assembly - has anyone done this yet?

I've read of other 200 lb riders, but no one's mentioned this problem (rear shock sags to limit with body weight) - Maybe I have a defective spring from Downtube? Is it working for other 200 pounders?

Thanks,
-J.R.
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Old 05-08-08, 04:42 PM   #4
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Just FYI, I broke the little collar of the rear shock assembly by trying to remove the spring. It sort of crumbled in my vice grips as I tried to twist it out to get to the spring. Now I need to at least get an OEM replacement, even if I cannot strengthen the spring somehow.
-J.R.
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Old 05-08-08, 05:41 PM   #5
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Hey J.R.

Sorry to hear your shock woes. Cast metal components are not as strong as machine bits. For a component that will bear such weight and pressure it's surprising that they didn't use a more appropriate collar.

Anyhoo, now that it's busted this will give you an excuse to get one of these!!


It has adjustable dampening for various riding conditions or style and due to a slight change in geometry for the swingarm appears to give a stiffer ride even tho the spring rate is 750 lbs. It's a bit taller than the stock spring but I'm ok with it personally. You will sit a bit taller.


Here's the link to the eBay seller I bought from http://cgi.ebay.com/New-Bike-Adj-MTB...2em118Q2el1247

The shortest shock he has is the 150mm one. Again, the longer shock will change your swingarm geometry a bit but it feels like it's making for a firmer ride than the stock shock.

HTH,

Norman
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Old 05-09-08, 04:51 PM   #6
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Wow, that's very cool. Thanks so much for pointing me to a replacement. It looks like a nice upgrade too! I am a bit concerned about the extra 2" of length - it will move my seat forward and that might put me into a bad pedaling position? I'll check it out though.

Thanks
-J.R.
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Old 05-14-08, 01:32 PM   #7
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Update

So I received a replacement OEM shock directly from DownTube (Yan) the other day, and it doesn't sag like the original one. It seems to support my weight much better, so there's room for compression when bumped. I am comfortable with it for now.

The amazing thing is that they sent me the shock free of charge - I didn't even have to pay for shipping. Great customer service!

-J.R.
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Old 05-14-08, 01:33 PM   #8
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I'm still looking for firmer elastomers for the front shock if anyone has any ideas.
-J.R.
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Old 05-14-08, 01:36 PM   #9
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I'm still looking for firmer elastomers for the front shock if anyone has any ideas.
-J.R.
Might I suggest stale marshmellows

Great to hear that Yan got ya fixed up. Is the Spring rated the same as the OEM?

Norman
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Old 05-14-08, 01:42 PM   #10
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Might I suggest stale marshmellows

Great to hear that Yan got ya fixed up. Is the Spring rated the same as the OEM?

Norman
Yes, the replacement has the same rating as the original. I wonder if springs loose their force over time? I had the original one half compressed on the bike with a high pre-load adjustment for about a year - maybe it lost some of it's "spring" as a result.
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