formerxcpro

Worked for SACHS back when this factory was making the Sedis chains, predecessors to all SRAM chains now made there.

I'm wondering when this was. "3 days of rain"? It hasn't rained here in months. 3 days in a row , maybe Spring of 2014.

it will be interesting to see what happens with Marin now that the Polygon bikes are available in the US. Polygon is the house brand for the factory in Indonesia that recently purchased Marin Bikes. Time will tell.

guess why that is.

Most of the single-track by my house if officially off-limits to MTB bike, but that was never enforced until recently. The trails are all maintained by the local Parks Deptment and mostly maintained by hikers. That being said, the mtb riders that ride them have a reasponsiblity to NOT be dicks to the hikers they encounter while riding them. Otherwise they ruin it for every mtb rider out there. Well, guess what happened. A handfull of guys build a new STRAVA DH trail complete with jumps and tied it right into the hiking trails. Hikers almost got killed by someone going for the KOM and now the trails are very-much off-limits to bikes and that is being enforced with tickets. Thanks guys. It only took one dick to ruin it for everybody.

By the way. Just because they call 650b "27.5", that does't mean it's 27.5" and its not half way between 26 and 29. Look up the ISO bead seat dimensions of a 26" rim, a 650b rim, and a 29" rim. 26" rim is 559mm, 650b is 584mm and 29er is 622mm. 650b is 1/3 of the way between 26 and 29. That is 1" diameter bigger, not 1.5" like most assume based on the inaccurate 27.5 name. My 650b wheel with a 2.1 Kenda Nevegal is exactly 1" larger diameter than my 26" wheel with a 2.1 Kenda Nevegal. That is exactly 1/2" larger radius. That's why most 26" frames and 26" suspension forks can be ran with 650b wheels. I have won cross country races on all 3 sizes. 26" is and will always be the best climbing and best in super tight single track but has it's limitations in super fast bumpy stuff. The 29'er rules on smoother, faster, non-technical stuff, and coasting downhill, but is a handfull when there is a lot of steep climbs and tight singletrack. 650b does a good job of splitting the difference. Nico Shurter is winning World Cups with it.

I rode that combo for awhile while I worked out clearance issues in the rear triangle for the bigger 650b rear wheel. Worked great.

part 3. The pro's you see winning races are on these, and the bikes in the bike shops come something like this. I wouldn't recommend doing downhill runs at your local ski resort with these. Using the same Moment of Intertia(MOI) formula, we can find out exactly how light a 29'er tire would need to be to have the same moment of interia as a 26" tire. Using the MOI of the Kenda Nevegal 26*2.1 at 66.5gm2 as the target, a 29" tire would have to weight 490grams to spin up like the 26" wheel. If you repeated the laps on the 29er and 800+ gram tires, you may get completly different results. At the end of the day, this is just my opinion. I eventually settled on a 26" FS bike, converted to 650b wheels. No crazy compensated geometry, no super-light tires to worry about, standard mtb triple ring still works (they don't work with 29, that's why they created the new 2-ring setups). Similar flick-ability of the 26, some of the benefits of a larger wheel, without the the draw-backs of the way larger wheel.

Part 2. Here are some Moment of Inertia calculations on these 3 different tires (the rotational inertia of the rim and spokes is being ignored here since it is minimal). The Moment of Intertia for these 3 tires is approx 66.5gm2, 76gm2, and 113gm2 (grams meters squared). Notice there is small difference between the 26' and 650b, but a huge difference going to the 29er. This is that R squared thing kicking in. Back to the "real" tire comment I made above. I consider a "real" tire one that I can ride the local trails with, works well in most terrain wet or dry. I can rip the local bike park with it AND race on it. A do-it-all tire. I don't keep mutiple wheels sets around with different tires for different things. I need a do-it-all tire and ones that durable enough to handle it. Notice that the Moment of Inertia is only slightly higher for the 650b tire than the 26" and it's the same great tire, same great tread pattern I like, and the size. Now look at the 29er". It's almost double the 26" tire. Now of course this is for a real tire, sized up to 29" diamter. If 29er bikes had tires like this on them in the bike shop, it would feel so heavy during the "parking lot" test that nobody would buy them. That's why they have "29'er specific" tires. These are typically smaller (2.0 vs 2.1 and bigger for 26"), have lighter casings, and thinner rubber with a race tread pattern. The pro's you see winning races are on these, and the bikes in the bike shops come something like this.