[Rum_Runner1]

I have a fuji Ace with a cyclone crank and wellgo clips. I want to know if I upgrade to the Ultegra clipless pedals will they fit my cheap crank? Basically I'm asking if all the sizes are standarized so any pedal will fit on any crank?

 

[alienator]

Yup. All pedals share the same threads for crank mountage.

 

[odeum]

shimano AX excluded...

Yup. All pedals share the same threads for crank mountage.

 

[Kerry Irons]

Pedal size

Essentially all pedals on any decent bike are 9/16" diameter, and 20 threads per inch, AKA 9/16 x 20.

 

[Dave_Stohler]

Essentially all pedals on any decent bike are 9/16" diameter, and 20 threads per inch, AKA 9/16 x 20.

Well, all decent bikes made since the mid 1970's. Before that, quite a few good Raleighs used an oddball whitworth standard-22 tpi, if I'm not mistaken.

 

[Bigchef]

Take it from my experience and wasted money

I suggest that you buy decent pedals. I tried cheap heavy pedals and realized I wanted better. So, the cost of the cheap pedals was lost. There are alternatives to Shimano. Great stuff too. Lighter, cheaper, better. Check the online stores and if you have a good LBS, try there. If you can, support the local guy. Might find what you want and on sale.
You can take some of the money you save and buy better cranks, or wheels, or tires, or...

 

[ARP]

Something to remember

It is not just a pedal, it is a system. Today that may not be important to you if you have one bike. I have about 3 or 4 that I switch off riding, I have one pair of shoes. So unless you only plan to have one bike, then it is not critical yet. Find a pedal system you like and marry it. You decide to change later then it can get expensive. I married Look system a long time ago and am about to divorce a set of pedals because of the creaking clip interface(it is the only pair of Looks I own that creak, sounds like someone grinding their teeth on every pedal stroke). Also, i have worn out 1 set of Look pedals in about 14 years, currently have about 5 sets of them.