Downhill bike sizing

My eldest boy has taken to downhill and it’s a good excuse to own a dh bike again for me to ride the the local shuttle tracks with him, rough steep and moderate speed is how I would describe them, down to the bedrock in most places. It will be the first time in decade I’ve owned a dh bike and I’m a bit lost with what would be the best size. At 5ft 5ft I’m firmly in the small to potentially medium range. For my trail bikes I always prefer slightly bigger bikes, around the 440-450 reach area but common sense tells me to size down slightly for a dh bike. Looking at a small V10 it has a smaller wheelbase than my s3 stumpy which somehow just doesn’t feel like it would be right. Anyone with any experience I would appreciate some input. 

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Stewyeww
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6/8/2026 1:02pm

You 100% don't want a DH bike with a shorter wheel base than your Trail bike lol

 

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TEAMROBOT
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6/8/2026 1:25pm Edited Date/Time 6/8/2026 1:27pm

I agree. I think the norm is that reach should tend to be the same or shorter on a DH vs. single crown bike, but wheelbase should absolutely be longer. The only way your wheelbase wouldn't be on a DH bike is if you already have a trail bike with DH geometry (i.e. longer chainstays and super slack head angle). I suspect that's not the case, because Stumpjumpers aren't known for having super long chainstays, and V10's are.

But even if your new DH bike has a similar wheelbase to your trail bike, you'll still notice plenty of benefits on your new DH bike once you point it downhill:

  1. There's no replacement for displacement. 200mm of travel will always be > 150mm of travel.
  2. The dual crown fork. Yes, it's that much better over rough terrain.
  3. Death by a thousand cuts. When you have a bike that is totally and shamelessly optimized for one thing only, it tends to be really good at that one thing. Heavier tires, bigger brakes, shorter cranks, bigger clipless pedal cages, a coil shock, wider bar, taller stack (along with a stiffer fork and more travel), and potentially tire inserts or pedal kickback devices will all combine to put a big smile on your face the first time you plow through rough chop.
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6/8/2026 1:47pm

I loved dh bikes back in the day, looking forward to riding one again. The book spec wheelbase on my stumpy 15 is 1218mm but it measures 1237mm in reality which does take it into small sized dh bike territory. I assumed a smaller reach would be better on a dh bike but I will maybe have to look for a medium to get something a bit longer than my stumpy which I find very comfortable to ride. My last dh bike was a 2012 devinchi Wilson, can’t remember what wheelbase it had but I’m sure it was very short, felt great at the time!

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TEAMROBOT
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6/8/2026 2:23pm

Just checked out geo charts for both bikes, and I would definitely recommend the medium V10 for you. If you're comfy on the S3 Stumpjumper with a 445mm reach, the medium V10 can be setup with as low as a 444mm reach. The small V10 is much smaller than your S3.

https://www.santacruzbicycles.com/collections/v10/products/v10-dh-s-2027?variant=51695610954010

https://www.santacruzbicycles.com/collections/v10/products/v10-dh-s-2027?variant=51695610954010

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6/8/2026 4:10pm

Ari S1 , it’s a Schmedium   Perfectly between medium and small. Suspension can easily be set for race or park riding 

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6/9/2026 3:17am

I ride a medium on my trail bike (455 reach) and a large on my dh bike. (470) And I’d honestly grow the dh bike a little bit if it was free.


Unless you just plan to hit jump lines all day I’d definitely get the largest size you can comfortably ride which would be the medium.  There are so many situations for Dh riding versus trail riding where stability >>>>> twitchiness.

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