Bike sizing

Question

i am currently 5'8 and still growing. i am looking at a bike that is 53cm. would this be big enough for me in a year. what size should i be looking at?

Answer 1

Yes it will be fine.  The saddle can be adjusted higher as you get taller.  the current trend is to use a smaller frame and have the saddle higher above the top tube.  This allows the handle bars to be lower and the rider will be more bent over with a straight back for  a more wind streamed profile during a performance event.  A smaller frame is also ligher.  Better to use a smaller frame than one that is too large for the rider.  Saddle to pedal distance is very important for proper leg extension and power.Don't worry if your feet do not reach the ground very easily.  Do you propel yourself by pushing your feet along the ground?  Your 53cm will be just great.

Answer 2

Unfortunately, there is no way of knowing.

Someone skilled in bike fitting and working with you in person could give you some insight, but...lacking a crystal ball...s/he still won't know.

There are some things you could consider in the meantime.  First, the frame size (53) doesn't tell you the whole story; mfrs use different methods of measuring frame size.  So, I'll ignore the 5' 8" & 53cm.

You should consider two measurements.  First is the standover height.  This is typically the distance measured from the top edge of the top tube (at the center of its length) to the ground.  If this measurement clears your pubic bone by an appropriate distance today, you can bet it will next year, too.  If it doesn't give the right clearance today, it's not a good (safe) choice.

The second measurement, and just as important if not more so, is the effective length of the top tube.  As you grow, both your torso length and the length of your arms will increase.  While you can extend the seat post and adjust the saddle to compensate for your growing legs, what are you going to do about your torso and arms?  Adjusting the seat post won't solve this problem.  Remember that the length of the top tube is largely responsible for your riding position.  Racers typically want longer top tubes (and shorter head tubes) that get their back flatter and their overall position more aero.  A shorter top tube will put them more upright, all else remaining the same.

You can compensate for some growth in your torso/arms by changing to a longer stem at a later date, changing the position of the stem on the steerer tube, and/or flipping the stem.  As you make these changes, the handling qualities of your bike will change some, which could be good or bad.

If the size you're considering fits you well today, it may or may not fit you well in a year.  How much do you realistically believe you'll grow during this year?  A former coworker of mine grew from a fraction over 6' to nearly 6'6" between ages 17 and 18.  In his case, I'd say there wouldn't have been a chance of making one frame work for those extremes.

If your purchasing this bike new from a dealer, have you discussed this concern with the staff?  One thing you could do is take a ride on the same bike in the next size smaller (51cm?).  See if it feels awkward, and try to determine what changes could be made to make it a good (or better fit).  Would merely adjusting the seat post make it comfortable?  How about switching out to a longer stem, from perhaps an 80mm to a 100mm or even 110mm?

I hope you get the answers you need to make a good choice.  If you have any doubts, perhaps dropping a significant chunk of change on a new bike that won't fit next year isn't the best route.  Find someone that knows their stuff and make a very informed decision.