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Stiffening a suspension fork -or- swapping with rigid?

Old 12-17-11, 10:37 PM
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Telly
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Stiffening a suspension fork -or- swapping with rigid?

Hello everyone,

My daily commuter has a RST Neon TNL suspension fork with lock-out and pre-load adjustments. Even though I have the fork in the lock-out position there still is some play, especially when braking (normal, not-panic braking but keep in mind that I'm overweight). The fork itself has around 500km and has been like this from day one, and my LBS says that it's in top condition with no leaks or other problems.

Is there any way I can increase the load pressure on this model? And if not, can someone recommend a rigid fork that would fit my commuter; keeping in mind that my commute is done solely on pavement.

Thanks!

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Old 12-17-11, 11:17 PM
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If you are willing to swap to a rigid fork , then swap to a rigid fork but it might not be that easy. Rigid bikes are simpler and lighter and probably less likely to be stolen. You will have to do some work to re mount the light and any connection to the front hub dynamo (I assume you have). The stock hardware may work fine or may not. Also, unless the fork and headset appear to be of the older 'threaded' style, and most replacements are unthreaded, so you either need to find a compatible threaded ones or use unthreaded fork and get a new headset a stem to match.
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Old 12-17-11, 11:29 PM
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I'm relatively new to this kind of modifications so can you tell me how I can check to see if my front fork is threaded or not? Also I've read somewhere here at BF that there are rigid forks specifically made to replace suspension units; if that's not the case, then how can I calculate the correct length of the rigid fork?

Sorry if I'm answering your post with more questions, but I am mechanically apt and would like to try this by myself.
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Old 12-17-11, 11:41 PM
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That looks like a threaded stem, but here's an article about threaded versus threadless systems: https://sheldonbrown.com/headsets.html

As mentioned, most forks these days are threadless. If you have a threaded fork and want to put on a threadless fork you'll need a new headset and stem. Of course, make sure the fork you're looking at has studs for your V-brakes.

Rigid forks meant to replace suspension forks are said to be "suspension corrected" and have a larger axle-to-crown measurement. That's the number you want to look at. The distance from the axle to the fork crown - the point where the fork disappears into the headset. Contrary to what many believe, I don't think this number is all that critical. Your bike doesn't have much travel, even if you put on a non-corrected fork I doubt it would change the handling much. I've done these sorts of swaps before with no issues.

Finally, cheap suspension forks suck. A rigid fork is much better than a cheap suspension fork especially for commuting. A suspension fork is really not necessary for commuting, and I think you'll appreciate how much lighter and more efficient your bike will be with a rigid fork.

Last edited by FastJake; 12-17-11 at 11:46 PM.
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Old 12-17-11, 11:49 PM
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the ideal fork will have an 'axle to crown' length and 'rake' similar to the suspension fork. The axle-to-crown is the distance from the centre of the axle to the top of the crown of the fork - the surface the bearing race sits on - measured along the steering axis. The rake is the distance that the centre of the axle is in front of the steering axis, measured perpendicular to the steering axis.

Most people just find out or measure the approximate axle to crown distance and get something close. The rake on most forks is not too varied. This strategy works for most people. If you make a very big change, it can dramatically change the handling. If you make a small change in these dimensions, i will only make a small change in handling and you will get used to it within the first few miles of riding.

But if you get a fork with a threadless steerer tube, you will probably have to get a new headset and stem. A threaded headset has several flat-sided nuts on the top of the steerertube, and the stem goes down into the frame. I think this is what you have. Most new bikes have a threadless sterrer and the headset parts slip on the fork and the stem is clamped onto the top of the steerer tube to hold everything together. If you want to buy a threaded fork, you need to get one with the same diameter steerer tube, and the same length or a little bit longer than the stock fork. Threadless stems are purchased in one uncut length and are cut to fit each bike.
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Old 12-18-11, 02:08 AM
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Forks with lockouts don't really make them truly rigid. They keep the fork in a semi-static travel setting with some "play" to account for unexpected big hits done with some sort of blow off valve. I had a Manitou fork with a lockout that I left locked out and I rode a trail. Went downhill fast and hit a raised tree sapling waterbar at the bottom and heard a loud "pffft" sound. The lockout stopped working after that.

Lower end suspension forks normally don't have much in the way of adjustments. If you're commute is solely on pavement, then the sus fork is just extra weight on the front end. Convert it over to a rigid fork. Steel or carbon is recommended as aluminum can give a harsh ride.
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Old 12-18-11, 04:23 AM
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Looks like 700c 35 sort of wheels ?, long legged cross forks , are maybe not
long enough to keep the head angle the same
perhaps the MTB type will be long enough in the blade, but the brakes
may not line up, then , and you would need to convert to disc brakes..

Which gets close to just buying another bike, in parts cost.
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Old 12-18-11, 05:54 AM
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Same bike, same problem, same thread and answers:

https://www.bikeforums.net/showthread...ont?highlight=



What I could find was a fork that was about 5 cm shorter axle - to - crown. Didn't make the swap. Hope you will make one and hear how that goes, before I do it myself. It should change the handling.

When measuring axle to crown dimension, sit on the bike, so the fork compresses like it normaly does for your weight (rider sag). Good luck, interested to hear how you do.
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Old 12-18-11, 06:03 AM
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Thanks for all the advice. Reading all your comments, I wish I could just find a way to make the suspension a bit stiffer; that I can live with. Otherwise I'll keep cycling, loosing weight and hope that I reach the point where the suspension won't sag as much during braking (even when locked).
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Old 12-18-11, 07:45 AM
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N+1 Nice used rigid frame mtbs are plentiful and cheap, and make great commuters. Buy right, and it will be cheaper than the fork swapout.

Just noticed you are in Athens, Greece, market is probably significantly different.
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Old 12-18-11, 11:03 AM
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Originally Posted by Telly View Post
Thanks for all the advice. Reading all your comments, I wish I could just find a way to make the suspension a bit stiffer; that I can live with. Otherwise I'll keep cycling, loosing weight and hope that I reach the point where the suspension won't sag as much during braking (even when locked).
Go to RST Tech Support. They have information on spare parts. You might be able to get stiffer springs or elastomers. Or you could check with your dealer to see if they can get the parts. On the other hand, a little brake dive in suspensions...even when locked out...isn't abnormal. I have high end Fox forks that dive a few mm each time I brake and they have very good lockouts.

A fork swap wouldn't be impossible but it would require some work. I wouldn't worry too much about getting a suspension adjusted fork since the travel on your bike isn't all that long. Again, if you want to go that route, work with your dealer.
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