Tuesday, September 2, 2008

A better 29er Front Derailleur

Recently, SRAM did their public launch of their new internal front mechanism, the Hammerschmidt. With that came a bunch of forum and blog chatter. However, I've seen little on the new Shimano SLX dual ring front derailleur and it just might be one of the coolest little items on the market. Maybe I've missed it. Maybe this is old news. Just maybe what I'm about to write will be new news.

Before I get into the details, you will need a little back ground info to appreciate and understand my perspective on this new product. Think about 29ers. Think about big 29er tires. Now throw in suspension. Now think about the 29er crowd's thirst for more travel and even bigger tires. Now make the chain stays as short as possible. Now add in the requirement to properly design and position a front derailleur. There is a lot going on down there in the crank, bottom bracket and front derailleur area of a bicycle.

Back in February I was in Southern California and had the opportunity to see some prototypes of Shimano's new SLX group including their dual ring front derailleur. Since then, I've been excited to install one and test it on my own bike. I received my SLX group back in June, but unfortunately Shimano only supplied a triple front crank and a triple front derailleur. Recently, I got my hands on their new dual ring crankset and front derailleur and immediately installed it on my full suspension Big Mama prototype play bike.

Before I installed the new stuff, I took pictures of my Shimano XT front derailleur and triple crank set up. Here is a top and a side view. Notice that the rearward, lower portion of the front derailleur cage overlaps the big 2.4 Schwalbe tire mounted on Salsa's 35mm wide Gordo 29er Disc rim.

Now, take a look at this set up with the new SLX Dual Ring Front Derailleur and crank set.

Amazing. To top it off, the front derailleur cage is designed with almost the exact radius as the outer bash guard. The system virtually eliminates the possibility of throwing the chain over the outer bash guard. Wow, a drive train optimized for dual rings, big tires, a 36tooth max chain ring. That sounds good to me. It works great too.

In addition to all this, the system is optimized for a Shimano dual ring crankset. Yes, I know it is currently only available in a 104mm bolt circle and a 22-36-BG. But I would argue that this is the ideal set up. I've been running my "Play" bike with a 22-32 for over a year. It does work great, but in reality when I rode this bike in the Colorado front range, in Fruita, in Grand Junction and in SoCal, the 32tooth was too small. When I'm climbing those big long climbs, I'm dropping into the 22 anyway, especially on my 30 lb play bike. For me, the 22-36 is an ideal set up.

All I can say right now is that I'm smitten with this set up. I really like it for how I set up and ride my 29er. I also think it opens up some new possibilities in 29er design and bigger 29er tires. We'll see.


Guitar Ted said...

gnat: Yes, this should be big news, the thing is, Shimano isn't marketing or promoting it that way, at least not that I've heard. (And you know that I look for this sort of stuff.)

It isn't rocket science, but still, I am amazed that they did it. An easy mod, really, but Shimano probably needed the dirt jump/FR/AM crowd to push them to this and 29"ers were most likely an afterthought. I'm just speculating here, but that seems to be the case as I see it.

At any rate, this will be a great derailluer to test out on my Raleigh XXIX+G which has 17.25" chainstays and has always had issues with derailluer rub in the smallest front ring. In fact, with anything bigger than a 2.3", I couldn't use the granny at all.

If SLX works on that bike, I'll heartily endorse it.

MG said...

You know I've been a fan of the 22/36 setup for a while now, and I too have quietly been watching the introduction of the SLX parts. I know you and I have discussed it in private as well. I was thinking the other day that I'd even like to try going 22/38 and see if I could make the jump. I can do a 16 tooth jump on my 34/50 Shimano compact road crank, so why not on a mountain double? Now that'd be a spread worthy of mention! A 22/38/BG combo would be absolutely devine on a 29er!!!

Bring it Shimano, please!!! and thank you.


Head Honcho said...

It is curious that we haven't really seen anything about this setup. Thanks for showing the pics Jason. The difference is remarkable. As folks get used to the new pricing, I see less and less XT being put on bikes, and more SLX. May get one for me...you never know!

chuck said...

Excellent photos, Butcher. I haven't had any chance to see this stuff live yet. If only I still had a 29er to put it on. :(