Toronto has a surprising number of climbs that will test the mettle of all but the most fit cyclists out there. While none of them extend much beyond a kilometre, there's some lactic-acid inducing gradients out there that will make enthusiast riders feel like their ascending the slopes of Alpe D'Huez, if only for a a few minutes.

These are my picks for the top hills for cycling in Toronto.

Brimley Road

Winding up the Scarborough Bluffs, Brimley Rd. starts tough and doesn't let up much until more than three quarters into the climb. Last time I road this one in 30+ degree heat, I thought I was going to have a heart attack (and I was in pretty good shape at the time). The gradient passes 12 per cent at times on this roughly two kilometre climb.

Twyn Rivers Drive

Arguably more difficult than Brimley and just as beautiful, Twyn Rivers curls up the Rouge Valley towards Toronto on a two lane road that looks every bit like it could part of a mountain stage in the Tour. You have to watch out for cars here as there's no shoulder, but it's worth the accomplishment of bagging this one.

Redway Road

Redway Road is the steepest in Toronto with a gradient that hits 18+ per cent up the valley wall. The climb isn't long, but I challenge you to do the whole thing sitting down on a road bike with two chain rings. The big bonus is that there's almost no traffic here, so if you're sadistic enough, you can do intervals. Beechwood Dr. on the other side of the valley is also a leg-burner.

Pottery Road

Pottery Road has always been a punishing Toronto climb, but it's become much safer since a dedicated bike/pedestrian lane was installed on the right side. Now you don't have to worry about the cars behind you when your legs turn to jelly at the top of the climb and you're prone to swerving into traffic.

Lawrence Avenue East

This low traffic climb starts at the base of Glendon Collge and heads straight up the ravine wall. This one gets harder as it continues, so don't be fooled when you get to the halfway point and feel pretty good. The best bet is get out of the saddle and pump up the last 50 metres of the climb.

Glendon College

Something of a sister climb to Lawrence Ave. East, this is one of my favourites in Toronto, but it can be quite dangerous. You have to ride against traffic to get up this tree-lined road, which comes complete with an 18 per cent pseudo-switchback at the top. Fortunately, cars travel slowly down the hill, so it's easy to give them a wide berth.

Bayview Extension

This is one of the longer climbs in Toronto, which extends just beyond a kilometre if you start at Pottery Rd. and finish at the Loblaws parking lot. It's not particularly steep, so good riders can establish a good rhythm and test out their fitness by flying up this one.

Poplar Plains

Probably the best place for interval training near downtown, you can head up Poplar Plains before working on your descending skills by flying down Russell Hill Rd., which has an awesome corkscrew turn at the bottom (if you're willing to run the stop sign). The last part of the this climb is the steepest, but it's just short enough to sprint up the whole way.

Humberview Road

There's a variety of hills that wind up the Humber Valley near Old Mill, but I tend to favour Humberview Rd., which makes the steepest ascent up. It's short but tough, and features much less traffic than the nearby Humbercrest Boulevard, which takes a more gradual route up the valley.

Kingston Road

The climb up Kingston Rd. from Woodbine to Victoria Park is nowhere near as steep as some of the streets that head north up the old Lake Iroquois shoreline (Lee Ave. is a good one), but it's one of the few ascents in Toronto where you can set a rhythm and climb for more than five minutes. There's a few flatter sections, but it doesn't get easier -- you just go faster.

What did I miss? Add your favourite Toronto climbs in the comments.

Photo by BruceK in the blogTO Flickr pool.