21 vs 20.5 TT?

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2/19/2017 1:02 PM
Edited Date/Time: 2/19/2017 1:40 PM

Is the size difference going to be really noticeable as a beginner? I'm 5'6" and ride a 54cm road bike. Longer torso. Mainly looking to do bunny hops, manuals and smooth flow riding. Nothing terribly technical.

Thanks

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2/19/2017 1:23 PM
Edited Date/Time: 2/19/2017 1:26 PM

In BMX we don't really do sizing, certainly not to the extent that road biking does but going off your height, I'd say the 20.5 would be better. It'll be a little quicker to turn so it'll make it very slightly easier if you decide you want to learn 180s and 360s. I've always found hopping on a slightly shorter frame is easier. Manuals are far more dependent on the chainstay length but a shorter toptube will make it a tiny bit easier to get into them.

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2/19/2017 1:41 PM

Gotcha, mostly going to be responsiveness. Meant to say 5'6" bad typing.

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2/19/2017 1:47 PM

Yeah, I second the 20.5" sizing.

While most of this BMX geometry stuff is personal preference, everyone grows more and more accustomed to their setup the more it's ridden, regardless of what type of ridding you put your bike through. smile

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2/19/2017 2:30 PM

Will focus on 20.5" frames thanks for the advice.

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2/19/2017 6:36 PM

I'm your height, Aescarion, and ride a 21" toptube as well. It feels just as good as a smaller toptube size. Dont restrict yourself to just 20.5, you might end up liking the extra room.

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2/19/2017 6:45 PM
Edited Date/Time: 2/20/2017 2:35 AM

Go for the 21" if you are more into fast and smooth riding than being a tech wizard.
Longer tube means stable bike because of the longer total wheelbase and the added room who gives a less cramped position, so more comfort and stability.
and 21" x 2.54 = 53.34 cm
It's close to what you ride now, even if the bike is fully different, bmx bikes are small enough to be a quick and funny bike without having to reduce the top tube size to make it even quicker.

To resume 21" is fine, a 20.75" would suit you well too but 20.5" is too short.
But as a beginner, you'll adjust to whatever bike you'll get.
And personnal preferences matters a lot and we sometimes end up seeing tall guys on small bikes and small guys on long bikes.
But you don't have preferences yet so try as many bikes as you can to see what you like, and figure out why
I am personnally a long bike lover (21.4" tt for 6'1) riding mainly street, I look for responsiveness somewhere else (short chainstays, high BB, short fork offset, shorter crank.... the list goes on).

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2/19/2017 6:46 PM
Edited Date/Time: 2/19/2017 6:55 PM

It's become a debate because I can get either an SE Gaudium for a steal of a price or a WTP Crysis for about 70 more. Former is 21" TT.

My Specialized MTB 29r is a 15.5" which is around 538mm actual TT length. So all the bikes would be roughly in the same ball park.

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2/19/2017 7:46 PM

Aescarion wrote:

It's become a debate because I can get either an SE Gaudium for a steal of a price or a WTP Crysis for about 70 more. Former is 21" TT.

My Specialized MTB 29r is a 15.5" which is around 538mm actual TT length. So all the bikes would be roughly in the same ball park.

Don't base your BMX off another different type of bike. Different types of riding have different requirements.

One thing you have to consider when asking this kind of question is the personal preference and experience of the repliers. I am 6'1" and I'm on a 20.75 whereas Francky is the same height and is on a 21.4. I've tried as low as 20" toptubes and as high as 21.25. To me both extremes felt like crap but to their owners, they felt amazing. I've settled over time on 20.75 as a point where I'm not too hunched over and it handles well on anything.

If it's more of a price thing, look at the parts and make a decision on what'll hold together best for you in the long run. Be sure to plan for the unexpected, you might at some point in the future decide to start learning some bigger things and learning bigger things is quite harsh on the bike.

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"Life should not be a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside in a cloud of smoke, thoroughly used up, totally worn out, and loudly proclaiming "Wow! What a Ride!""
- Hunter S. Thompson

2/20/2017 5:05 AM

I have no problem getting a second bike later on. Upgrading parts is a definite as time goes on also.

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2/20/2017 5:51 PM
Edited Date/Time: 2/20/2017 5:52 PM

I am 6'2" and ride a 21". I used to run a shorter Fiend frame and hated it! I'm nice and comfy on this one now for sure! But it's whatever you feel most comfortable on. It's hard to answer these kinds of questions as to what you're going to be comfortable on or not. I have a job that pays me well so I have the finances to be able to play around with stuff and be able to find my sweet spot. Some don't though and that's ok!

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2/21/2017 6:41 AM

I am 5'9 and I ride a 20.75 top tube. For me it feels just right because it's not too big to where it doesnt feel clunky as if i was riding a cruiser or something along those lines but also feels responsive. If I were given a chance to change to a 21" I might give it a try but 20.75 feels really good to me. 20.5 should be just right for you. I have a lot of friends your height who ride 20.5's with no complaints.

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2/21/2017 12:38 PM

Well as it ended up working out I have a 2017 SE Gaudium on the way. I needed to order bikes for the shop and it came down to supplier and pricing. Will see how it feels and I can always get a different frame or even complete down the road. If all fits well I can work on upgrades as I need them.

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2/21/2017 4:19 PM

Honestly you will get comfortable and be fine on whatever. If you anticipate growing a fair amount (base off parents etc), consider a 21 with a shorter reach stem.

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2/21/2017 4:25 PM

Hah. I'll be 38 this year. Not going to be growing much. Longer torso and arms here, stem change is planned if needed.

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2/22/2017 7:54 PM

You can be short and ride a long frame and be perfectly fine, you could be tall AF and ride a short and still be perfectly fine it really just depends on what's more comfortable to you. I'm 5"8 and I'm most comfortable on a 20.4 - 20.6" and I've ridden all sizes up to 21.25 and all kinds of rear ends from 14 - 12.75 so for me a shorter frame and shorter rear end is best for me.

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