Should I be on a medium or small bike?

Hi Lee

I just signed up for your RideLogic bike setup service. I’m 5’8″ and am a little stunned at the difference in dimensions that it recommends vs my current bike.

I have one of those long low 27.5 Whyte bikes, and I ride a medium with a 450 mm reach (The RAD on that bike is WAY longer than what RideLogic recommends, but it actually feels really good).

I was shocked when your article said I should be on a 410 mm reach bike. I am looking at 29ers (never owned one before), and I rode a Guerilla Gravity Smash medium which was at 460 mm reach and I hated it.

After looking at RideLogic, I should have demoed the small instead. Most of the bike websites out there say I should be a medium and the average reach on those is 425 mm which still have longer RAD numbers. Do I really need a small??

It looks like RideLogic doesn’t discriminate on someones proportions (arm length, inseam etc). Do those factor in or is it pretty standard that someone who is 5’8″ will fit into a certain RAD?

Matt M.

Hey Matt!

First of all: If you love your bike, keep on loving it. If you find a setup that works for you, work it.

In my opinion, 450-460 is a long reach for someone of your height. You can make it work, but with these caveats:

  1. If you have great mobility and skills, you can ride just about anything.
  2. You might not know what a great setup feels like, so you don’t know what you’re missing.
  3. You might be more than a passenger than an engaged driver — and you might know what you’re missing.

The basic RideLogic setup suggestions at the Lee Likes Bikes MTB School are based on average proportions. The best ways to find your specific RAD are to 1) use the on-bike check and 2) measure with a RipRow. Both of those methods account for your proportions. They are detailed in the Bike Setup section of the site.

The site also has an advanced calculator that lets you input your specific proportions, but it’s easy to make measuring errors.

I’m about 5’8.5” tall and rode the small Guerrilla Gravity Trail Dogg. It was a fun bike, but with a reach of 440mm it was still a bit long for me. I’d prefer the extra small. My 2017 Enduro Coil has a reach of 430mm, and that’s about as long as I want to handle.

More and more riders will be well served by “sizing down.”

The new Dialed book describes all of this in detail. No website membership required.

I hope this is helpful,


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