(I own a https://www.rei.com/product/784255 which currently has a cheapo Suntour fork, non-OEM on it)
I can't figure out what size the fork steering column (which is the part that the handlebars ultimately attach to, am I correct?) should be for my bike... Any help would be greatly appreciated.

Also, I'm trying to look for a new fork for my bike; I'm 110kg (240lbs) / 1.9m (6'3), and have a budget of ~$100. I'd like a fork with lockout / the SPV that I read about in the newbie MTB thread, but obviously on budget that's probably impossible... New or used, I'm fairly indifferent.

Thanks for reading

20:1 odds it's a 1-1/8 steering column. You can confirm this with a ruler. Use a 5mm hex key to remove the top cap screw and cap (don't loosen the stem clamp) and measure across the hole at the top. You don't need great precision because it'll be either 1" or 1-1/8", and if you can't tell them apart, quit now.

Next you'll need to know how tall, which is another simple measurement, from the top of the fork crown (bottom of the headset) to the top of the stem. Consider this the minimum length when buying a used fork, new ones will be plenty long and need cutting down.

Your real challenge will be finding something decent within your budget, but be patient and you might find a cast off decent fork from someone who upgraded.

Thank you; i'll do that in the morning when I have some light to go by

How about the specifics on a fork to best-fit my specifications (6'3 240lbs)? Are there any specifics in terms of spring tensions, the best height, etc that I should keep an eye out for? Or is this all bike/preference dependant?

I'd love to help, but I tend to ride tried and true old stuff and so don't keep up with all the newest offerings. Besides there's isn't a single suspension fork in my fleet, which is more of a reflection on the type and quantity of mountain biking that I do, then a statement for or against suspension.

According to the website the bike is intended for a 100 mm travel fork. Staying true to that will mean the least changes in bike behaviour, although the bike will still remain rideable even with quite drastic changes. Going shorter tends to make bikes squirrely, while going longer makes it a bit sluggish in steering. Going longer will also increase the strain on the head tube. Bikes will generally survive this, but it isn't advisable, particularly at your weight.

Some forks used to offer replaceable springs, for the ability to tune the fork to rider specifics. I still see that for rear shocks, but it's been a while since I saw it for forks.
Air-filled forks do require more upkeep, and are likely to break your budget, but do offer great adjustability.
Want it stiffer? Pump some more air into it.
Lighter forks tends to be flexier, and some even come with manufacturer's recommendations about rider weight. Allow the fork some weight, and do read the fine print.

The fork listed in the original spec is supposed to have a 1 1/8 steerer.

100mm travel means the distance that the shocks will "travel" to absorb something, correct?

Thanks for the informative response

one more question; if I buy a fork off of craigslist or something, and go to pick it up personally, are there any allignment things that I should keep an eye out for? I assume dents and such aren't great for a fork, but are there any underlying problems that I could spot with a little inspection?

Suspension forks are comparatively rigid and rarely get mis-aligned, and you're not equiped to make critical measurements anyway. Here's what you can do.

1- examine overall condition for signs of good care, or hard use.
2- examine the stanchions, especially the wiping area that the fork telescopes onto. Any dents, nicks or rust here will degrade performance, especially air and oil shocks which need to maintain a good seal through the travel range.
3 - mount a wheel you know to be true and centered, and see if it squares up perfectly in the fork.
4- with the wheel on the ground, stand over the fork and lean in to compress it. The movement should be smooth and even.

This doesn't assure a 100& perfect fork, but will help you weed out serious issues and make a decent judgment call.

Alright, I'll be sure to bring a true wheel when / if I go to buy a CL fork

Thanks a ton!

That's a good precaution, "my" regional forum have had two posts the last week about forks bent out of alignment. I've bent one too, aided by another rider who t-boned me.

Kinda, sorta. The travel is the distance between fully extended and fully compressed. (give or take a few mm for whatever happens between theory and reality).
But most of your riding is done with the fork already partially compressed (called sag), so you won't be getting the full travel when you hit a bump. You might get full travel when you touch down after the bump though.

You will not find an aftermarket new fork with lockout for $100, It just is not going to happen ..
You probably won't find a rigid suspension corrected fork, new, for that..

Used shopping, I'd have the length of the steerer tube on your bike's fork in mind , bottom of the lower headset to top of stem .
and not even think about one Used that is not that long.

Longer is great, You can add spacers , even above the stem , to see if you like a given height, before sawing too short.

Yeah, lockouts imply higher end forks and you won't find those at your budget. In fact you're not even going to find a decent fork at that price point for new. Double it and now you're talking but for new and $100 you're better off with a decent rigid.

Used is obviously a different matter. Shop well and be patient for a highly motivated seller and you can score really well. Along with a few quick eyeball alignment checks to ensure that things are not bent look at the swept area of the stanchion. Any bad scratches or dings say that the seals will not last long. ESPECIALLY dings in that area. They stanchions need to be pristine or walk. Anything less will soon lead to worn or torn seals and fork oil leaks. Try to wiggle the sliders against the stanchions as well. Worn bushings will allow a degree of play. Most forks will have a very small bit of play but if it's easily seen instead of barely felt then the bushings are too far gone to ride well.

Wow; I didn't expect any more replies to this. Thanks for the tips; I've got time, being very careful with this purchase because it's hard earned money and I want to get the best bang for my buck; i've got CL rss feeds set up and I check them every half an hour or so on my phone

About rigid forks: That's a neat idea, but, how durable would that be? Again, I'm a heavy guy, and to me it just seems like it would snap or something on a particularly hard landing. I'd def. consider one if it would hold my weight, and be able to handle my rather sloppy technique.

As fietsbob said, make triply sure that any used fork you buy has not had the steerer tube trimmed down too much for your setup. It's a classic mistake to buy a used fork and discover upon assembly that the tube isn't quite long enough for the frame/headset + stem. Also, make sure the fork has disk brake mounting tabs/posts.
As a minor note, although you shouldn't see anything else, you are looking for a "threadless" 1 1/8" steerer on the fork.

I got a new, rigid, suspension-adjusted fork for my bike and I love it. I don't mountain bike any more, but when I did I never needed a suspension fork.

This is my saga (I didn't unscrew the top to find out the real diameter of the fork tube, therefore my 1st guess was wrong)

https://www.bikeforums.net/showthread...rk-and-headset

This is my fork

https://www.bikeman.com/FK0001.html

They also look SO much better than suspension forks

You can get some really solid rigid forks that are tough enough that the wheel will blow up before the forks let go. But if you're jumping the bike then you'll want good forks. Frankly if you're jumping lots and high then you need to expand your budget and get something with a solid rep for laughing off lots of punishment. There's nothing at all wrong with the 100 mm travel forks but I consider the Avalanche to be more of a cross country style bike that is more happy sticking to drops of less than 3 feet for riding on a regular basis. If you are thinking of going bigger than that I suspect you've got the wrong sort of bike right from the get go and should have gotten a more burly urban or mountain big drop bike.

Well, it's not that I take 3 foot drops, or even 1-2 ( I am a novice, after all ), but I'm just concerned that my weight will be a big strain on a rigid fork; what characteristics are there to look out for on a good rigid MTB fork? Also, how will the handling differ on a rigid fork versus a fork with suspension(I've read a mixed pot of things; most say it improves your handling, others say it hurts a lot, others say it doesn't hurt at all, etc. )?

I assume that, because of the lessened complexity of a rigid fork, they can be had for higher qualities at lower prices? (also, apparent lower maintenance doesn't hurt at all for me )

The failed rigid forks that I have seen have all either been high mileage commuter forks, or damaged in crashes. And the occasional Jackass-inspired stunt of course. Never seen one fail during "regular" use, whatever that would mean.

If you're worried there's always the MTB trials riders. Any rigid fork that can take their usage has to be pretty much immortal under "regular" circumstances.

A good review on something like mtbr.com obviously doesn't hurt. Apart from that there isn't that much you can do realistically. It's the usual stuff of course, known distributor, known label on the fork(big names tend not to sell substandard parts), no obvious flaws in the workmanship. Allow for some weight and cost. Having both a weight budget and a price budget makes it real easy for the manufacturer to provide a strong product.

Roadies tends to talk a lot about comfort, vibration and road buzz. But for a bike running a MTB sized tire the tire will absolutely drown out whatever contribution the fork has to make to that.
To stay as close to the current handling of the bike you want to look for a fork with an axle-to-crown measurement as close as possible to what you have now when you are on the bike.
Then there's rake too. Rake is basically how much the for protrudes forwards. Easily seen on old steel forks with the curved legs, less visible on modern designs.
IME these things are rarely critical, pretty much whatever you do the bike will still remain rideable. Who knows, you might even prefer the change. Some people set great store to these things though.

If you try to ride rigid w/o adapting your riding, you will suffer in every way. There are things you suddenly can do and things that you suddenly can't do. At the "downside" you will need to be more more active with your arms. Don't wait for the jolt, anticipate the bump, be ready to bend the elbows and unload the bar when you go over some roots for instance. At the upside the front of the bike will be probably 2 pounds lighter, so yanking the wheel away from danger will suddenly be a lot more doable. it'll feel more responsive overall.
Generally speaking you'll want to be more active in your riding, pick your line more carefully and move your body around more.
Kinda fun, but more strenuous.
The real downside IMO is when you start to get tired. With suspension(and decent air pressure) there's always an option when faced with a moderately bumpy stretch to simply aim the bike, get up from the saddle and go for it. This doesn't work half as well when you're on a rigid.

It does different things under different conditions. When fatigue begins to set in a sus fork will help. When size of bumps begins to exceed what can be soaked up through upper body movement a sus fork will help. Before these conditions occur a sus fork is mostly ballast. Provides some comfort but you pay for it with a bit of sluggishness. And of course, the point where one situation transitions to another will be different for each rider.

It's really the moving parts, and the desire to keep the weight down that are the culprit. Once you ditch the moving parts it gets quite easy to build something strong enough w/o going to ridiculous dimensions and exotic materials.

Well, maintenance for a rigid fork is pretty much a non-issue. There's the headset bearings and the brake, but that's about it. The occasional wash and inspection for rust/damage should do the trick.

High-end air shocks OTOH come with quite tight service schedules for those who wish to keep them working at optimum. And after three services I will have payed more in maintenance than I did at the original purchase....

Yeah, so I've decided upon a rigid fork, however, I don't know how long it should be? I measured the fork that's on my bike at the moment, and my axle (the place where the wheel fits, dropout, right?) to crown (place where steering column and fork legs meet?), is 20inch/508mm, which seems to be larger than a lot of rigid forks I'm looking at. Maybe i'm measuring incorrectly?


(the bottom part of the tape measurer is on the dropout, 20inch mark is where the crown apparently meets steering column)

Heh, just looking at the image makes me think that there are a 1,001 things that I'm doing wrong with my bike.

But that's measured w/o sag. Once you get on the bike the fork should compress a fair bit. That's the measurement that you want to use, as it's closer to average riding conditions. Can't get your pic in full size, so I can't see if you're reading the measurement right or not.

This URL should give you the full image view https://img37.imageshack.us/img37/3221/biketv.jpg

So, once I sit on the bike, I should take the measurement and search for a rigid fork with the closes measurement to that?

Yes, though you'd need really long arms. Have a friend measure, or you can do it empirically and subtract about a third of the forks rated travel from the unloaded height. Super precision isn't called for, because forks only come in a few sizes.

My firewall liked that one a lot better ;-)

And looking at it, it seems like you're a tad off. My interpretation of the pic would put the crown race at maybe 500 mm - but it's a bit hard to judge angles.

That's the starting point. Getting a rigid fork at the same length as your sus fork would be while JRA will mean the least change in handling. It's a good goal to aim for, but don't sweat it of you can't get it spot on.

And a way to make the measurement easier is to put a zip tie around the fork leg right up against the seal while the fork is uncompressed. As you get on the bike, the zip tie will be pushed upwards. Then you can measure the sag, and subtract that from the uncompressed length.