The biking thread

[Eunos_Cosmo]

New chains are almost always too long and need shortening to the desired length. There's no doubt that it's far too long, there shouldn't be any slack even on the small-small combination - well no, you shouldn't use it, but shifting mistakes happen and you don't want the chain to go all limp in such a case - but now it's not good even on the big ring.

Before ordering a new one, even though $50 isn't much, I would have checked if the old derailleur would actually have worked although it's said that it doesn't. The medium cage XT derailleur, for example, doesn't officially work with the 10-51 cassette but in reality it does. There's always a ton of safety margin in the compatibility claims so that people don't get it wrong, break stuff and then complain that it was said to work.

The only downside in a longer cage is more chain movement on rough surfaces but unless you're doing the Aremberg forest at race speeds daily you won't notice a thing. Oh, and when you install it (if you do it yourself, otherwise ask the one doing it) put in a new cable too. Cheap and easy to do when the derailleur is off anyway. And don't leave the barrel adjuster that much opened, cables will stretch, housings may compress, and that one is close to the outer limits already.

I tested my existing RD and for me it was too close for comfort. At MAX reach, the jockey wheel was basically in the teeth of the largest cog. Shimano rates it at 28t. If I was going up to a 30t, or even a 32t I would be inclined to try it. But a full 6t more I think is asking too much. The R7000 is a bit lighter, designed for bigger cogs, and from what I've read shifts a bit nicer too. I'm gonna do the shift cable too, though I might have a shop do that part.

 

[Greycap]

Do the shift cable yourself, it's not that hard. Not because it's expensive at the shop, but to learn to do it. Basically in a nutshell: put it in the highest gear, roll the shifter rubber grommet off enough to be able to see the cable end, detach it from the derailleur and see how it was fitted. Pull the old cable out from the handle, thread the new one in, fit it in the derailleur, pull it really hard so that there's no slack anywhere and tighten the screw. Adjust from the barrel adjuster as necessary, cut the cable, fit a new end plug, roll the grommet back and call it a day.

Meanwhile I'm reworking the donut mobile a bit more, it was basically finished last spring but we've had so much snow recently that it's seen more use than I ever expected when buying it. With more riding experience the small shortcomings are getting irritating - the tyres are original from 2014-2015 judging by all evidence and the tread feels more like a car radiator hose material than a bike tyre, and the 170 mm cranks are really too short as I have a pretty bad case of a princess syndrome with them and indeed need 175 mm. Anything shorter feels like the FWD kids' tricycle.

With the eventual new tyres I'll do a bit of a "who dares, wins" setup and use undersized tubes. Everyone says tubeless is the best thing you can do to a fatty but I've had more than enough of it with the XC bikes, sure it's nice when it fixes small leaks but when the tyre gets properly ripped it's of no use so you'll need to carry a tube and tools anyway. Not to mention the amount of mess when putting a tube into a tyre that a few minutes ago had sealant in it, of course in field conditions at some trail side where the sealant remains will pick up anything smaller than a squirrel that will then puncture the tube on the way home. So, several people say a 26x2.5-3.0 tube works just fine even in a 26x4.8 tyre and that's what I'm going to try. As an added bonus they weigh some 200g a piece while actual fat tubes are in the 450g ballpark so less rotating mass and a much thinner layer of rubber following the surface contours. If it goes kaboom then so what, I'm never very far from home with that bike anyway.

 

[Eunos_Cosmo]

I bet you could see straight through that 2.5" tube pumped up to fill a 4.8" carcass