Anyone here in Colorado?
 

I have two weeks in Broomfield coming up, starting from the 29th of September.

I'd love to hire a bike and go up into the mountains- any residents of the area who could advise?

If this is lunacy I'll just take my running shoes, but the mountains look enticing.

Why would it be lunacy? Because of snow or something? Just last night, we got snow in the foothills of Boulder and surroundings, but it will melt off by tomorrow, when the high is supposed to be 72 and 81 on Sunday. Early October is often the best time for riding around here; just watch out for the occasional snow storm that melts off by the next day or so. In a two-week time frame, you are very likely to catch some nice fall days for ridings in the foothills. Note: I never ridden in Broomfield, but my guess is that it contains lots of sprawl, so you may just want to head up to Boulder or Golden and start your rides from there...

I'd need to hire a bike, best to catch a ride to Boulder and find a hire shop there?

Boulder BikeSmith...they rent decent bikes.

Boulderbikesmith.com

$35 for eight hours on a Giant Defy.

Now to find a club going out on a Sunday.

No offense, but what elevation are you coming from? If sea level, then I would advise against trying to hook up with a club to go uphill, unless they are 70+ years old or you are well acclimated to the elevation and in pretty good shape.
Look on strava for hilly rides in the area or search past threads here.

Signature link indicates London, so sea level.

In my experience simply Denver / Boulder proper, not even in the "real" mountains yet, are noticeable for us lower altitude types.

Boulder
 

There is great climbing in and around Boulder, which is close to Broomefield, that are great. Just ask at one of the shops or check out 303cycling.com for climbs. University Bicycles also rents quality bikes. CX season is in full swing out here. Races in both Sat and Sun on most weekends if you're into that sort of thing.

As surmised I'm normally at or around sea level, when I came out in January I ran a half marathon in ~1.45, but did find that faster paced efforts saw me run out of steam earlier than usual.

So I take your point on that one, might be better to head out on my own.

Thanks for the links I shall investigate further.

There's great road and mountain biking in or close-to Broomfield.

Marshall Mesa / Dirty Bismarck is a good start and can be linked up together for some good mileage (25+ miles). It's just West of Broomfield in Superior.

Check www.mtbproject.com for the trails

For road riding, Hwy 128 from Rocky Mtn Airport and West is some good rolling hills, but not crazy elevation climbs like Flagstaff or Left Hand Canyon in Boulder.

If you're coming from a near sea level elevation with few hills, the Denver-Boulder area would be better.

Denver-Aurora has many miles of dedicated bicycle trails that do have a few hills. The Cherry Creek Reservoir area has some fairly challenging climbs for a flatlander. I noticed the locals didn't have much difficulty but I did.

Living in Denver, riding Denver
 

I live in Denver.
Broomfield is lousy riding-but easy to get to Boulder or Denver, foothills for great riding. Fall is fabulous - afternoon rains are mostly rare, temps very moderate. Need wind shirt for early or late. Elevation typically not an issue for most healthy people IF you remember to stay hydrated. Best bike club ride on Sundays is found at:
rmccrides.com
And their Sunday rides are typically flat(ish) and more recovery driven. There are also rides typically listed at Meetup.com
Rentals? I like Boulder Cyclesport - but there are many others
PM me if you want more info - or want a riding companion. ...

why broomfield?

broomfield is terrible. close to denver and boulder, though.

Jayfree- thanks, I'll take you up on that.

Why Broomfield? Our offices are there.

Probably silly question - I need to post my SRM cranks to SRM, once I land.

Does UPS/etc have bricks and mortar establishments I can walk into to do this, or will I have to arrange a courier to pick the parcel up?

How does this work in the US?

Either a UPS/FedEx/Kinkos store or get some free boxes at USPS and mail from there.