May 28, 2017

Exposure to "Frame Geometry." Whoa.


I just picked up a Yaabaa 749 for a good deal, I found on my local Craigslist. I have always ridden 'old' bikes. (a couple of Monty's: MOD, and a Planet-X: STOCK).

So, I have been riding this Yaabaa for a few days and holy smokes! What a difference! (as compared to the x-Hydra).


The wheelbase is only slightly longer (10mm) than the Monty, but the BB rise is significantly different. I was doing MUCH MUCH better on the rear wheel hopping in a matter of a few minutes... NOW, getting back on the Hydra? I don't think so... LOL.


I did try the Hydra again and "pulling" the front end of the Hydra up is 'hard work' - the Monty feels much heavier too.. Haven't weighed the bikes though.. I'll be spending my practice time on the 'newer' geometry.


I'm hooked on this newer frame geometry... I guess this is what happens when you are 'away' for a while. The bikes have really changed in the geometry 'dept. - not just overall weight.


May 29, 2017

They figured out a way to make rear wheel everything better... also brakes are getting crazy , I just switched from the classic 2005 hs33 to a race line / trialtech line/ trialtech lever. It is mushier but only slightly, it is insanely strong... only problem is I need 2 more of the same set up, I've only one on two bikes... $$$$

May 29, 2017

I did 'side-by-side' measurements with the MODS I have.

I thought the BB Rise was a bigger difference than 5mm. Looking at this comparison chart, it seems it is the combo of differences that gives the 'improved' feel/effect.


The Hydra is only a little heavier. Also, a past owner of this 749 changed the cranks/sprockets.

The cranks are longer than original, and the bike now has a 18T rear FW / 24T front. (New it had 12T rear / 18T front FW).

I wonder what the reasoning was behind the sprocket/crank change up?


May 29, 2017

I'm a total noob so I might be wrong, but doesn't the shorter chainstay make a bigger difference on rear wheel hops than the BB height?

May 29, 2017

I am certainly a noob when it comes to effects of frame geometry - I know what I read - and have little experience (last week or so) on bikes with different geometry. So, that's a good question regarding: chain stay versus BB rise. I read they both are factors. I'm guessing you are correct that having your center of gravity closer to the rear wheel would have greater affect than a bit higher BB rise.

May 30, 2017

shorter chainstays, higher bottom bracket, and the longer reach are all going to make rear wheel hops feel much easier. The yaabaa is modern, but some of the newer mods are even lighter feeling on the rear. I definitely think it should help you progress more quickly! Looks like a fun bike :)

Jun 8, 2017

I too love the new geometry. I was riding a 2005 Echo and found what I think is 2009 frame new, unused on Ebay. What a huge difference. I am 44 years old and ride better than I ever have. Even though the frame is old by most standards it was a big jump in performance for me.


Jun 9, 2017

Jeremy, After I posted the Yaabaa frame specs I found a 2017 Echo 24 on Craigslist for a pretty good bargain and grabbed it. This thing is lighter than the 20 inch Yaabaa. And the chainstay length is the same yet the wheel is bigger. Needless to say, I am having a GREAT TIME on the Echo! Your Echo looks pretty similar (my BB might be a bit higher and my stem is definitely longer).


If you run into anyone wanting to start in trials, I am selling my old school rig LOL. A Planet-X Evil Eyes frame, ready to ride. ;-)


44 years old! Go man go. I'm 55 and I'm working hard at it..


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