Tuesday, September 1, 2009

Banshee Legend MkII

As most of you know, a total of 62 Legend MkI frames have been used, abused, raced and podiumed over the last 18 months, all in the name of progress. I have had huge amounts of feedback and suggestions from a lot of great riders, bike mechanics and engineers, and I have tried my best to take it all on board and use it to develop, refine and improve the Legend for the MkII version which will be available to the public for 2010.

In general the feedback was very positive. Everyone seemed to comment on just how fast this bike was and the majority loved the way it rode, but there was definitely room for improvement.

I'll admit that we did run into a few issues. The biggest issue was pivot wear... not the bushings wearing out, but the axles! I've tried a couple of different materials, but due to the high loads and large diameters combined with wide angles of oscillation wear has proven to be an issue on the legend. The other issue with bushings on the legend frame has been stiction if tolerances are not spot on, or pivots are over tightened. So after much debate, I have switched the design to run on high quality (INA) large diameter fully sealed cartridge bearings, combined with a new pivot assembly to reduce friction in pivots to an absolute minimum, whist still being able to handle the loads without needing to be replaced regularly.

To put this in perspective, the bearings I am using in the main pivot where loads are highest are 6202-2RS bearings which have a 35mm OD. Bigger bearings cope with bigger loads. All the bearings I have used are also common bearings, and so affordable and easy to source. If you did need to do a full bearing replacement for every pivot, then I calculated total cost to be around $40 if bought from a regular bearing supplier. I was checking out a competitors bike, and the main pivot which takes similar load to the legend main pivot, uses a bearing that only takes 1/4 the load, and costs almost 4 times as much!

I considered needle bearings and double row angular contact bearings, but after some number crunching and load analysis, the deep groove ball bearing came out on top. It can cope well with lateral loading (which happens a lot in DH racing) as well as the axial loads that the suspension demands. I have kept the pivot assemblies as simple as possible, as well as fully floating, there is zero friction caused by friction on washers or anything like that. All pivot axles will be manufactured from high grade steel (12.9Cp) and we will be looking at doing a racer upgrade kit in titanium in the future to save some grams, and add a little bling.

The bearings themselves add a little weight over bushings, but I have cancelled this out by weight savings elsewhere, while also making the bike stronger in the process.

It is not just the bearings that have changed however, there have been literally hundreds of tweaks and alterations based on the feedback I received. Not a single CNC part remains the same as the last batch, everything has been looked at again and refined or totally redesigned. It might take a keen eye to spot them, but there are changes almost everywhere to strengthen, lighten and generally improve the design and make it more compatible with parts like chain guides, as well as improve manufacturing tolerances by changing assembly patterns.

Other main changes:

  • There will only be one travel setting of 8" (203mm)
I found that nearly everyone rode their MkI legends in the one setting the whole time without switching except to give the other option a quick try. I feel that 8" is the right amount of travel for the majority of DH courses.

  • Suspension linkage
I have modified the linkage geometry and components to make the leverage curve a little bit more linear (was slightly too progressive before). This will make tuning shocks easier, and offer the rider slightly more control and traction.

The axle path is not as initially rearward as before, which reduces the chainstretch and pedal kickback experienced. Don't worry, it is still more rearward than most DH bikes to give great square edge bump absorbtion, but will feel more controlled now, as the radius of curvature of the axle path is not as tight.

  • Geometry

Well, I'll let the following geo table do the talking here, but essentially the BB has dropped, the head angle has slackened, and the top tubes are longer. The longer top tubes have pushed the weight up slightly, but only by maybe 100g or so. We'll post actual weights when we have a couple of protos ready.

I think I have covered everything now, and anything I haven't you will probably be able to spot in the following pics from my computer screen.

Oh, I'm blatantly going to be asked about cost and availability dates... Cost has yet to be confirmed as it depends on a few factors as well as the shock that we ship the frame with. Availability will be early 2010.

I want to just say a big thanks to all those legend test riders out there who have supplied me with feedback. I have done my best to adjust everything accordingly to follow the general trend. I couldn't have done it without you!

If you want to know more about anything, or have any other questions, then just post it in comments below and I'll answer as soon as I can.