Hey Erik, I’m building my large Susie with the same 2.5” Terravail Tires but I’ll be using Riv’s 13-42 7-speed so that I have room to fit a bigger tire in the back if I decide to do so and because why not? I’d be happy to measure the distance between the chain and tire once built so we can compare and we can both get an idea of how going either way affects it. At first I was going to wait for the new 7-speed hubs that Riv is working on but decided that going with a 9-speed hub and spacers gives me more options.
Joe > On May 25, 2022, at 5:16 AM, lconley <[email protected]> wrote: > > The solution to wider tires on the rear while maintaining tire clearance and > chain angle is a narrower cassette with spacers on the inner side - the 7 > speeds that Rivendell and Soma sell. > Note also that long chainstays keep the chain angle smaller than with the > same chainring and cog offset on a shorter chainstay bike. > > Laing > >> On Wednesday, May 25, 2022 at 1:28:49 AM UTC-4 Erik wrote: >> Well, that sand looks brutal! As you noted, the max listed tire size on the >> Gus or Susie is 2.8, but I feel like that would be pushing it for a couple >> of reasons. I'm running 29" x 2.5 Terravail Ehlines. They measure about >> 62mm without any weight on them on Cliffhanger rims, tubeless. They have >> plenty of clearance on the sides (about 12mm on the front, a little less in >> the rear). I measured the distance between the inside of the chainstays and >> it looks like it's right about 80mm (I wasn't measuring with calipers!), so >> I don't think you could fit 3" tires (about 76mm) with any meaningful room >> to spare. The forks have a little more clearance so maybe a slightly larger >> front tire would be possible. >> >> The bigger issue that I would see with trying to get even larger tires on >> the back is the bottom bracket width necessary to keep the chain off of the >> tire. It would push the chainline out pretty far. It's a 73mm shell and >> I'm running a 122 IRD bottom bracket with spacers. Even with that and a >> chainline that is waaaay outboard, the chain runs pretty close to the tire >> in the 50t gear in the back. I think that if I sized up even to the 2.8 I >> might have to switch up to a 127 BB, pushing the chainline out even further. >> You almost need Boost spacing at that point to push the cassette further >> out in line with the front chainring. Otherwise the front chainring is >> starting to line up with the smallest cog which makes for a terrible >> chainline. That's my amateur opinion at any rate! I'm sure someone on here >> has tried it or knows this better than I do. >> >> Otherwise, even with "just" 2.5 inch tires it's handled the terrain just >> fine and was easy to keep on track on multiple surfaces, including rocky >> sections and sections with lots of roots and loose gravel. It was equally >> fine with all of it. Sand, however, is another matter. We don't have much >> of that on the trails in my area so I can't really speak to it. >> >> I may try out a larger front tire soon and will happily report back. I >> don't think I'm going to try a larger rear tire for the reasons above re: >> chainline. >> >> And thanks for the nod on the build! Happy with all the shiny bits. >> >> Erik >>> >>> > > -- > You received this message because you are subscribed to the Google Groups > "RBW Owners Bunch" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/rbw-owners-bunch/a823e109-8404-45da-ba1e-530eb28795b5n%40googlegroups.com. -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/rbw-owners-bunch/8B1F7FA8-57E7-4EF0-B265-28CFA34D78A0%40gmail.com.
