Have a look at http://www.macbike.nl/ or http://www.mikesbikeamsterdam.com/ or hire them at the Centraal station.
Be careful as the roads could be very slippy if it is at all cold. Blackice is common at that time of the year. Also be very careful at traffic lights - watch out for lorries turning right- I'd hate for you to fall under one. trams and more importantly tramlines are a hazard too!

Station Zuid-WTC - train station not far from your hotel has a bike rental place in it.

I would not advise city biking in Amsterdam, esp in winter - biking IMO in Holland is best in good weather and then thru the countryside on the myriad of bike paths.

Trams and buses are so good in Amsterdam - a tram goes from near your hotel and the city centre is so compact - insurance? well if your bike is nicked then the sizable deposit you must put down will be forfeited - rental companies may provide insurance but no helmets (i've asked several and they laughed)

Like hetismij says city biking has its perils - bike paths that are crowded with speeding commuters and add any ice...

thanks for the advice guys. so dont rent??? darn, i was looking forward to checking out the city on bikes! guess i'll have to wait until next time we get out to A'dam.

I really would save cycling for a spring/summer/autumn visit, and then rather than cycling around the city get out to the nearby countryside and enjoy the bike tracks away from other traffic.
Helmets are not normal in Holland, unless you are a racing cyclist. If you want to wear one then you need to bring your own.
The bike may be insured against theft/damage but you need some insurance on your self also. Not sure how third party claims would be covered.
Theft of bicycles is a real problem so if you decide to rent and leave the bike do make sure it has a good lock with it, and chain it to something solid!

I recommend a spring time ride in the countryside also. Or for a city cruise get your training in Haarlem before venturing out in Amsterdam. Dutch bikes handle differently than anything in the USA.

In Amsterdam you might hire a bike rickshaw with pilot/navigator. They are everywhere and cost about €25 per hour.

We've rented from Mac Bike at Leidseplein a number of times, but I think it would be far too cold to be biking in December. We usually go in April or September - temps are decent then.

If it is just cold it isn't a problem cycling - you get warm from the exercise after all. Dutch people don't put their bikes away just because it's chilly. BUT if it is freezing then you do have to be careful as the bike tracks and roads can be slippery even though the council does it's best to salt/grit them. The same is true of the pavements of course, but as a pedestrian it is easier to spot ice than as a cyclist.
Cobbles tend to be slipperier than normal roads or paving slabs too.