The Karlie Wonderland wood wheel is the quietest I reckon - virtually silent. They are nice sturdy wheels and the 29cm is a good size for any Syrian, small or large. Occasionally someone gets one that has a few splinters, so they need checking over carefully, especially on the inside near the struts. I just sanded my last one inside with grades 100 and 240 sandpaper - very lightly - took 10 minutes. Then paint it with plastikote paint which is pet safe. It helps seal any rough bits you might have missed and helps waterproof it.
This is the Plastikote paint - I brushed it on with a half inch paint brush.
http://www.amazon.co.uk/gp/product/B...rch_detailpage
The Trixie wheel can be noisy and rattly (so can 'silent' spinners!).
The next quietest wheel after the Karlie wheel, if you don't fancy a bit of sanding and plastikoting (although it really was quick when I did it - a coat dries in an hour or two).
Is the Wodent wheel. I have the larger Wobust 30cm one and I'd call that silent. Some people end up with one that squeaks a bit but then you oil the spindle with veg oil. The standard size for a syrian is the 27cm senior wodent wheel, which should be fine unless your hamster is a mahoosive one like ours.
They are hard to get hold of but the sugarglider site sells them for about £15.50 - they import them. Postage is about another £5.50. You get to choose the colour of the front and back plates and the running track and it comes fully assembled.
Here are the links for the two wheels. I like both of them. But I think the Wodent wheels work best hung from the top of the cage - ours runs much more smoothly that way - gravity I guess! It's easy to do - you slot the stand through a bar on top, attach the wheel inside the cage and the base just rests on top of the cage, but needs about 3 cable ties to secure it. The other advantage of doing that is it saves floor space in the cage - the substrate goes under it so more room for digging (or just hiding under the wheel!)
Wonderland Exercise Wheel: Great Small Pet Accessories at zooplus
11" Wodent Wheel (Senior) & Free Tail Guard
Yes Kaytee and Superpet are the same company - they changed the name recently but I can't remember which one changed to which!