Tuesday, December 04, 2007

650B Truth?

650B tire size? Let's see now, mountain biking wheels come in the oldish standby size that supports 26-inch diameter tires (the so-called standard), then along came the 29er stuff (29-inch diameter tires), and now there is a new (actually quite an old standard) size that is 27.5-inches that has long been dubbed 650B (not to be confused with 650C).

Hmmm...this new-old 650B idea really peaked my interest since I have been seriously looking into the concept of building or buying a full-suspension 69er (that's a large 29er front wheel and a small 26" rear wheel on the same bike). Why?...I have tried several 29er full-sussy bikes and just never felt at home one. On the other extreme I found I have a preference for 26" full-sussy bikes, but I also found that I dislike the small front wheel (it's much more prone to endo action and I really hate going over the handle bars). So the whole bigger wheel in front and smaller wheel in back on a full-sussy bike made sense to me and I wanted to find out if it would be the ultimate super-butt squish ride for me.

So I was drooling all over Trek's new top Fuel 69er (actually I still am - yes I want one) when Kirk Pacenti alone had a real 650B mtb tire made - that man has some serious faith in the 650B tire size to pony up the $$$ to have one mass produced (yes it takes money to make a tire mold). After many obsessive "research" hours spent looking over the whole 650B thing I decided I was going to build a FS bike of my choosing and drooling that was like the Trek 69er, but built with a 650B tire up front vs. the overly large 29er tire up front.

My Ellsworth Truth is the bike I chose - you may recall that in earlier posts I said the bike was a rough draft...well that rough draft has come much nearer to completion with a Pacenti Neo-Moto 650Bx2.3 tire mounted to a Velocity Blunt 650B front wheel laced to a DT Swiss 240 disc hub (HOT!!!) that I just built up. I also enhanced the rear wheel with a Bontrager Jones ACX tubeless tire mounted onto Stans Notubes ZTR 355 rim laced to a DT Swiss 240 disc hub. More enhancements are still planned so I have the say the bike is still in draft form.

The ride with the 650B front wheel is better than I had hoped...more testing (time trials, long hauls, and pure sufferage) as weather permits, but so far all I can do wonder in awe...Is this a bike I will actually keep longer than a few months? Any bets?

6 comments:

Anonymous said...

Great pic. Your truth is much the same as my Ram 4.0 that I was wanting to 69. your post at mtbr and another showing a 650b fitting into a fox f100 has ahcnged my mind. I will now do a 67.5er

Anonymous said...

Very Sweet bike Super E.
So you have a tubeless in the rear and a tube in the front? I am planning on doing a 27.5 in the front of my full suspender, but I go through tubes in about 5 minites where I live in pinch flat city, N.M. Any ideas?

Eric Kop-ski said...

Super B - I'm going to try a 650B tubeless setup using a Stans Flow rimstrip in the Velocity rim...I'm not sure it will work but for me it's worth the effort since thorns are abundant here.

Anonymous said...

I'm waiting for Stan's ZTR 355 rim he is coming out with in the spring. This setup should be more foolproof. I'm not a fan of tires without a UST bead though, but it will have to do until...

Hope you are enjoying the ride. Again, it is a very sweet setup. Nice to have an option of a bigger wheel up front. 29 is too large for a bike that was not designed around it, and there are not many full suspension 69ers to choose from. I love my Rush although Ellsworth would be my second choice.

KJR said...

good looking so far.

I've got an '07 32 TALAS R on my 5" dual suspension bike - tempting to do this as I do like the feel of my 29er HT as well. The Fox fork action is so nice...

Any travel issues you have to deal with (like limiting)?

I run 819s so I'd look to convert a Velocity - any of the existing rim strips work, or would the 26" tube cut open have to suffice?

I run Stans Flows on my 29er, they'd be great in 650B size as well.

SDJacobson said...

Thanks for the beta - looks like a nice set up - inspired me to try it out...post some results later in the season