If you plan to convert your 20" wheelset to a 24", you will have to note that the difference of 4 inches in wheelsize is too great. You may have a problem fitting the tyres through the fork installed. Even if you change fork to one for 24″ wheelsize, you will face issues with the frame.
As you can see from the image of this frame, the area mark “X” gets narrow towards the seatpost tube.
So, it is likely that the tyres will be touching the sides of the frame once the tube is inflated.
It does not matter if it is a regular bicycle or a folding bike, As you can see from these image of a folding bikes.
There is not much clearance space to fit a larger rim even if you remove the mudguard.
Find out how much it will cost you to buy a 24″ wheelsize folding bike. If you consider the cost and service fee to change the rims and replace tyres and tubes, you may want to consider buying new.
When you buy a fork for mountain bike, you have the option to buy one with suspension or without. There are forks in the market for 20″ MTB like the one shown here. 20″ MTBs are usually recommended for kids of age 6 and above.
If you plan to buy a replacement fork just make sure that it fits the size of the bicycle you intend to install it on. They come in sizes for 20″ right up to 29″ bicycles. Choose one with suspension if you plan on riding off road as it will take the strain off your shoulders during bumpy rides on your bicycle.
If you buy a cheaper fork with suspension, it is likely that you will not be able to adjust the shock absorbers as there is no dial on it to adjust their tension or to lock it so that it does not move at all.
BMX forks do not have suspension and they are usually built sturdier and stronger than other fork without suspension, eg, meant for a fixie or a regular 20″ bicycle. You will not be able to install your BMX rims or tyres on a fixed gear fork as the tyre width for BMX can be as wide as 2.35″
Mountings on the fork for the brakes are located differently for V-Brake, U-Brake or disc brakes. So, inform the shop the kind of brakes you intend to fix on your BMX.
In Malaysia, it is now popular for youngsters to modify their 20″ BMX with a double fork (with or without suspension) like this.
This is how they want their BMX to look like after modification.
Or like this.
This is how they ride (fly) the modified BMX.
This is dangerous and illegal. Bicycles like these get confiscated by the local authorities if riders are caught in the act.
