Frame Sizing Advice

[TrailSeeker]

I’m trying to determine the right frame size to go with on a Specialized Stumpjumper hardtail. I would love to hear some of your personal experiences on the frame size you’ve chosen in comparison to your height,weight, inseam, etc. Personally, I’m right at 5’7 and 1/2" with a 31 inch inseam at 150lbs. I do favor a smaller more manueverable feel, but i’m not sure if the 15.5 would be too small. I mainly ride XC with some technical as well. Any insight or advice would be appreciated.

Thanks!

TrailSeeker

[Slyp_Dawg]

I’m about the same build (maybe 2-4 inches taller and about 5lbs lighter) and from the advice my local performance bikes shop gave me, when sitting normal-like on the bike, if I look down at the front axle, the fork tubes should block the quick-release ends from view. at least if the front axle is offset to the front of the fork tubes. based on that, I ride a 19.5" GT i-Drive 5.0 DS. there are times where I wished I had a bit more manuverability, but it is very stable at top speed. if I want a bit more manuverability then I’ll get a fork that has the axle directly in-line with the fork tubes.

[Bombardier]

It’s hard finding the right size frame if you don’t have an LBS with a bike sizing machine handy.

However, I generally give the following advice, based on a few starting parameters given by the rider.

A. What is your riding style? XC/race, Trail, AM, or Freeride/DH?

B. Do you want a nimble bike, with a bent towards slower, more technical singletrack, or are the majority of your rides fast and flow-y?

Starting with the basics, you want a frame that, with your riding shoes on, the top tube should clear your groin by at least 1, 1-1/2 inches. After that, when balanced on flat ground, and your feet on the pedals at 3 & 9 o’clock positions, your knees should be directly about your ankles. That is not as important with mountainbikes as it is with roadies, but it’s a comfort issue, especially if you have joint problems. Over or under extending your knees during an even pedal stroke both wastes energy and can cause pain.

Then, you need to figure out your favored riding position. If you like to be stretched out and in an attack position for sprinting or climbing, a slightly larger frame will allow you to be in such a position while running a flat bar and not put your center of gravity too far forward. A smaller frame with a riser bar is better if you spend as much time or more going down than up. It will put you in a more neutral, upright position, and be more forgivable when the time comes for a dab or quick dismount.

Based on your original question, I’d say yes, a 15" frame would be too small for you. I’d say look for a 16, 17, 18" frame, with the 17" being my guess as being right for you.

When you go looking at rides, ask the LBS to remove all the spacers from under the bar. Generally, bikes come from the factory with up to 3 too many spacers. The idea is to set the bike up for the beginner riders by putting them in an upright position, which is acceptable for beginners, but a big difference is made when the correct bar is used with only one or no spacers on the steer tube.

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