drowling23

I bought my son a 24" bike with a Suntour fork (63mm travel, straight 1 1/8 steerer). The fork is abysmal junk and should be destroyed with a hydraulic press. Meanwhile, I want to buy a decent fork. Except there are no good 24" forks.

So I'm thinking 26" fork with 100mm travel, giving a vertical difference of about 37mm+1in=2.5in difference. I would aim at 2.5" tire width (Maxxis Hookworm), and probably would get a new front wheel, since I want an axle instead of QR.

Question: which fork should I get? Price doesn't matter, I just want the bike to actually have suspension. (Not the first time I'm throwing a Suntour in the bin.)

cyccommute 

That's a significant increase in height. More importantly, it's going to slacken the head angle significantly. Going to a shallower head angle is going to have an impact on the bike's handling. It will make the bike more stable on downhills but on climbing the wheel has a tendency to "flop" over from side to side. The steeper the climb the worse the wheel flop.

I would suggest an 80mm fork rather than a 100mm fork. It won't raise the front quite as much. The only problem is finding one now. A used one on Fleabay is probably the way to go. The best ones, hands down, are going to be a Fox. Air sprung Manitous aren't bad. Rock Shox are okay, especially for someone lightweight (they don't work all that well for heavier riders in my experience). Just make sure that anyone of them is an air fork.

On the other hand, you are talking about using a slick tire I'm assuming that you are going more road oriented, so why not just go with a rigid fork? Unless you are riding off-road, a shock has little utility. There are any number of 24" rigid forks out there. Your local bike shop should even be able to order one from Quality Bike Products.

Retro Grouch 

I'm thinking that if your objective is to improve the bike's handling, that's not a good way to do it. If you are convinced the stock fork needs to be replaced, I'd probably go with a rigid fork.

agmetal

What kind of brakes does the bike have? If V-brakes or cantilevers, it won't work without also changing the wheel.

Kapusta

You want to stick a new through-axle fork, new wheel, and new tire on the front of a 24" kids bike?

If money is no object, just get a 26" bike.

As far as how much the fork will raise the front end, it is not as simple as subtracting the old travel (67mm) from the new travel (100mm) and adding an inch.

First, you need to look at the differences in the axle-to-crown distance of the two forks. The fact that the new fork is for a larger wheel will likely mean that this distance would be larger even for similar travel numbers.

Then you need to add half the difference in the tire circumference. Don't assume it is 1" without checking (24" and 26" are approximations)

Then you need to add on for the fact that you are sticking on a 2.5" tire which is probably a lot fatter/taller than whatever came on this 24" bike.

My guess is that you are going to be raising the front end at least 3" which will slack the head angle out at least 5 degrees, which is huge. And the BB will be raised about 2/3 whatever the front end it raised. Oh, and the seat angle is also going to be slacked out as much as the head angle.

Either put a rigid fork on there or buy a 26" bike.

drowling23

Thanks for the advice everyone. However, a rigid fork is not an option because biking infrastructure is nonexistent here and curbs are everywhere. So some front suspension is definitely a must (I already have a Thudbuster for the back).

Buying a 26" bike is not an option because it would be far too big (even an S frame). I think we'll get a few years out of the 24" frame before going to 26".

Kapusta

How about a 24" fat tire in the front?

I see 24" fat tires for sale, there must be forks for them.

Here are a bunch of 20"-24" fat bikes. maybe you can score one of these forks.... or the whole bike.

If a small 26" bike is too big, then jacking the front of his current bike up 3+ inches may also cause problems.

Lazyass

This is a decent 24in fork.

https://www.ebay.com/itm/NEW-SR-Sunt...MAAOSwl2haA1Mo

fietsbob

yes the nominal radial difference is 1", so that is probably how much higher the head tube moves, lowering that angle ,

increasing the trail a bit , so it will feel different,

but the kid may adapt quickly ti that, but the meeting of the rim brakes and the rim wont happen..


is this a suspension fork?

Have you considered taking it apart and blocking up the inside parts, so that makes it no longer moves, so as to have a rigid fork.. ?





....

Kapusta

Besides the wacky things a 26" fork and wheel will do to the bike handling, if he is too small to fit on a small 26" bike, you are going to have a hard time getting a 26" suspension fork to work well for someone as light as he is.

cyccommute 

Kids have been riding over curbs since bicycles were invented...some kid was probably riding over curbs before bicycles were invented. It hasn't stopped them. They could probably learn a bit of finesse as I see a lot of flattened rims at my co-op but even that doesn't seem to stop them.

That said, I can see where you are going. What you want to do isn't going to be that cheap. I would stick with the 24" wheel in a 26" fork to keep the front end down a bit. You'll need to run disc brakes. I don't know what bike you have now nor what brakes it uses but if it has rim brakes, you'll need discs to make it work.

Like I said above, get an 80mm fork instead of a 100mm fork which will also keep the front end down. I would also look for a high quality air fork because an elastomer fork is going to be difficult to get soft enough to make the fork anything but a defacto rigid fork. A Rock Shox SID, Fox Float or Manitou would be the best choices. They aren't going to be that cheap however.

All of this isn't going to be cheap. The shock could cost you $200+, new wheel (if your wheel isn't disc) $50 to $100 depending on what you can find, the brake caliper $35 to $50 and possibly labor if you can't do your own work. That's dragging $300 pretty seriously and pushing $400.

And, like Kapusta said, it may be hard to get the fork to move even if it's an air fork. They aren't really meant for superlight riders. That may even be the problem with the fork you have now. It's not a wonderful piece of engineering by any means but the problem might be more rider related than the shock.

Kapusta

I just had a thought (uh, oh)

What exactly is the problem with the fork the bike came with? You might be able to fix or mod it to work better.

drowling23

The problem, to put it simply, is that Suntour forks are just for show - they don't really offer any suspension. Of course this needs to be put into perspective - I ride with a Fox 34 Factory so I'm kind of used to butter-smooth suspension. I suspect the real issue is the child is not heavy enough to cause actuation of the Suntour fork. However, when I reduced the pressure by half (from 60 to 30psi), the fork folded.

RLTennant

Hi there, I know this is an old post, but wondering what the outcome was here? We have a nice 24” Islabike but the Spinner shocks it Came with have now had it and want to replace for younger child. Money is tight and not much is on offer for 24”. We thought of buying decent but used 26”.... any thoughts?