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I have a question about wheelbuilding and tubeless setups: my rear tire just blew off the rim, what did I screw up? I just built my first set of wheels (Velocity Cliffhanger 36h rims, Miche Primato hubs, Sapim Race spokes except for drive side rear Sapim Strong spokes, using the different thickness spokes to help compensate for the different tensions). I've set up tubeless once before with no issues (Hunt 4 Season Aero wheels and 38c Gravelking slicks) The rims have a max tension of 120kgf, so I built the rear drive side as close as I could get to it using a Park Tool tensionmeter I borrowed from a friend. Rear drive side tension was pretty much 110-120kgf, and with the hub's ~40% tension ratio, to get the dish correct the non drive side was around 50-55kgf. Tubeless tape was Velocity's valves and velotape, two layers (one up to each inside sidewall, overlapping in the middle). The build finished and I went to my garage to get the tubeless setup going. Inflated the rear tire (new Gravelking SK 50c) with a tube to get one bead seated, and levered the other bead mostly closed, enough that I could get things seated tubeless by removing the valve stem and using a floor pump. I put the finished rear wheel on the bike and pumped it up to 60psi (the listed max for the tires). Spun it a few times while I got things started on the front tubeless setup to distribute the sealant. No hissing or weird noises, it seemed to be sealed fine. As I was futzing with the front, with the rear wheel sitting motionless on the bike on the stand, there was an explosion. My right ear didn't hear an explosion, just started ringing... it was super loud. Sealant everywhere, tire sideways totally off the rim but 100% intact. I set the whole thing up again, but realized that the rim was no longer true (sigh). Brought it inside and measured the tensions again, a few NDS spokes are down to 40kgf and some of the drive side is down to 90ish, with a few as low as 85kgf. Gonna see if I can true it tomorrow or if the rim is just bent now. What happened here? Is my floor pump off and I put too much PSI in the tire? Something with the wheelbuild I'm missing? I did set up the new front wheel tubeless as well, and it seems to be fine (though I did pump it up to only 50psi to be safe). Man_of_Teflon fucked around with this message at 05:32 on Dec 23, 2020 |
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Dec 23, 2020 05:28
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eSporks posted:Is it holding now? It held 20psi overnight just fine. I don't see any issues with the rim at all beyond it no longer being true; no tiny cracks or obvious bends to be seen. I was definitely surprised when the tire wasn't shredded given how loud the explosion was! edit: the rim is definitely bent now  I can true it, but the NDS spokes are now 50-75kgf with the DS spokes 105-135kgf, and it's still not quite as true as before. Dish is off a couple mm with the hub towards the DS too, despite the increased NDS tension. How bad of an idea is it to ride it like this and keep an eye on the tension?
Man_of_Teflon fucked around with this message at 16:18 on Dec 23, 2020 |
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Dec 23, 2020 14:59
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Ah man that sucks to hear Velocity has a bad rep. Any favorite wide (25mm or so) touring rims, US built or not? And what's a good minimum NDS tension to shoot for? Does doing NDS radial help at all? Worst case I can rebuild these wheels with different rims, but I'm still stuck with the wide offset ratio of the rear hub (just over 40%).
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Dec 23, 2020 18:01
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Salt Fish posted:You didn't mention a budget so DT Swiss TK540. This one's a bit narrow in comparison. The only other 700c rim I'm finding that is 25mm+ ID and can take rim brakes is the Ryde Andra 40 (conveniently the same ERD), which seems fairly cheap at around $55 shipped from Europe. Any issues with Ryde as a brand? CopperHound posted:Sorry for your wheel building disaster. I am curious how tight of a fit the tire was on the rim. Did it pop up onto the bead shelf easily or did it take that full 60 psi, swearing, and soap to get it in position? Mounting it tubeless was doable with just a floor pump, no soap. Just used a tube to get one side 100% seated, and then levered as much of the other side up onto the bead as I could. Pumping fast into a valve with the core taken out got it to catch enough to build pressure, and it popped up completely around 30-40psi I'd say. I got everything back on the bike and rode it up and down the alley at around 35psi. No creaking/popping noises or surprises, though I do see that one spot on the side of the tire does dip a little lower, as if the bead isn't out all the way. Plus the dish of the wheel is still a couple mm off, which made adjusting the brakes interesting.
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Dec 23, 2020 19:58
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It has proved doable to set up cantis for rim braking on a rim that wide. I would go discs, but I really like my 64cm Black Mountain Cycles Monstercross frame. If I ever do make the switch though I will check out DT rims, thanks!
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Dec 23, 2020 20:53
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So I ended up buying a Kinlin XR31T offset rim to replace the Velocity Cliffhanger that got bent during the tubeless explosion I posted about not too long ago. The offset rim would let me have a tension balance of roughly 120kg/65kg which looked a lot better, and it was one of the very few offset + 36h + rim brake rims I could locate. Unfortunately I was halfway through putting it all together when I realized that the Kinlin rim arrived with two messed up nipple seats . One is missing material all around, making the nipple sit maybe .5mm lower due to thinner spoke bed. The other is missing a chunk of material on one side of the spoke hole (you can feel a sharp edge lip where it drops off), which of course makes the nipple seat at a terrible angle.Really wishing DT made that TK540 with an offset... Man_of_Teflon fucked around with this message at 07:01 on Jan 3, 2021 |
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Jan 3, 2021 06:56
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What kind of spoke tension drop is normal to see after mounting a tire? I went from 120kgf to 90kgf DS, and 60kgf to 50kgf NDS tubed (all rough/average). Just hoping to avoid another explosion when I go tubeless again!
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Jan 15, 2021 02:02
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just don't ever pump tubeless up to 60psi to make sure they are seated like I did, because apparently it can loving explode off and trash your rim and tire! my 50c gravel kings also will not stop weeping sealant... I'm still mad at tubeless.
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Apr 16, 2021 19:07
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Literally Lewis Hamilton posted:What brand of sealant? effeto Mariposa caffelatex oddly it seems to not weep at all through 38c gravelking slicks
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Apr 18, 2021 16:16
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Looks like a little more spring pressure on the left side there would do it.
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May 12, 2021 21:02
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It sucks but I'd do #1, yeah.
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Jun 29, 2021 21:09
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What causes older indexed shifting spacing to be off to the point where it seems like the spacing between the index points is wider than the spacing of the gears on a cassette? I have worked on a zillion old bikes at the local coop and I also fix up old donated bikes for refugees in my basement. Within the last two weeks I have encountered this specific problem with two bikes, one 8 speed and one 7 speed, both with SRAM gripshift shifters. 7 speed in particular doesn't seem to really have any possible variation in gear spacing. In each case I swapped some parts around to see if it made a difference but all I have handy is other gripshift shifters and old metal derailleurs... each time the problem seemed to remain exactly the same. Is the is just worn parts in general, or are there some weird cassettes with the gears actually closer together trying to drive me insane??! No wobbly pulley wheels, no super gummed up shifter cables, hanger and dropouts seem fine... not sure what else it could be. It's frustrating because all the other old bikes I've worked on shift fine when adjusted properly, which is quite easy to do.
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Dec 21, 2021 06:16
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I finally opened up the one gravel tire tubeless wheel I had, which was also always leaking a bunch, and the answer was that my rim taping job was crappy - it was peeling up in various places. maybe try re-taping the rim after cleaning it?
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Jan 4, 2022 21:35
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just throwing more grease in gets most crappy old hubs back to working just fine. cleaning off all old grease and dirt and replacing any obviously chipped bearings or cones is even better for long term life. and if they are nice hubs... might as well replace all the bearings and keep the removed ones that look fine for beater spares. I've never seen a hub hosed up enough to damage the races on the hub itself (though some get old grease so caked into it that it's nearly impossible to remove), but I've only been working on old bikes in quantity for a few years.
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Jan 19, 2022 23:41
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wild, how do they set the races in the hub?
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Jan 20, 2022 07:08
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any recommendations for parts distributors that are willing to work with very small 1 person home bike repair businesses? I have an S Corp lying around & all the required crap there, just no commercial location (which QBP requires).
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Mar 18, 2022 05:07
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i did similar with 11-50 HG and a 42t apex crankset and it worked fine
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Sep 15, 2022 15:35
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jamal posted:And then without going electric shifters there isn't an off the shelf setup that lets you use a 12s mtb cassette with drop bars. microshift does make a 12spd bar end shifter! that’s what i used and it was great (but i love bar ends)
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Sep 15, 2022 17:15
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I was able to cobble together a press from an enormous c clamp (bent it in the process a little) and a socket to get a cottered crank off, which let me clean and regrease a bottom bracket instead of buying a weird 71mm 26tpi one on an old Raleigh just remember after reinstalling to ride a few miles and retighten the cotter, otherwise the arm is likely to twist and gently caress everything up
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Oct 14, 2022 22:16
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brand engager posted:Do those adapters to fit a nicer bottom bracket into a 1-piece crank frame work well? It's got this kind because it was a $130 bike https://www.parktool.com/en-us/blog/repair-help/bottom-bracket-service-one-piece I have an old schwinn super sport that someone put one of those adapters to BSA on, and it has worked fine for a couple years now. still not exactly lightweight but definitely a better BB!
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Dec 6, 2022 01:43
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how did that not break anything else? (to be fair my usual method is turn bike upside down and start hammering)
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Dec 18, 2022 20:58
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long pull levers on short pull brakes will make it difficult to apply the brakes strongly which is a bad idea
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Feb 27, 2023 06:40
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it would actually be the opposite if you hit the brakes hard - it wouldn’t apply the brakes as strongly as the proper levers. same force over a wider total range of motion in the brakes. the opposite scenario with short pull levers on long pull brakes would apply them extra strongly, but you would have a terribly short total range of motion in the brakes, which would be hard to set up without rubbing all the time.
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Feb 27, 2023 15:14
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Mauser posted:The larger chainring keeps the chain more taught and smaller chainring to largest cog also does similar. this sounds like the derailleur isn't strong enough to maintain tension when it is taking up as much slack as possible. when you are in large/large, is there room to take any links of the chain out? that could be a fudging it sort of solution...
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Apr 5, 2023 04:27
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the metric I always hear is 1" of flex total up and down in the center, but I think in practice just focus on avoiding any binding at the tightest spot while getting it close with cheap cranksets the tightest to loosest spots vary so widely that tight is almost binding while loose is almost falling off
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May 9, 2023 18:50
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Good catch, thank you!
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May 11, 2023 05:39
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I grease square tapers every time I’m reinstalling them! I think it makes sense: https://www.sheldonbrown.com/brandt/installing-cranks.html
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May 31, 2023 04:06
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The link I posted discussed a believable issue with greasing the taper: that when greased, the pedaling action wiggles things and lets the pressure from the locking bolt/nut move the crank further onto the taper, which makes the bolt/nut feel looser (how much is debatable, but for the sake of this scenario, loose enough to where the mechanic feels inclined to tighten it more), the mechanic tightens the bolt/nut and then the whole cycle repeats until the aluminum crank has been split open by the steel taper. the solution it mentions is... don't keep tightening! I have installed many many square taper cranksets and I always put on a thin layer of grease, tighten them firmly once, never tighten them a 2nd time, and I've never had anything come loose. Riding all winter too, never had to deal with corrosion preventing removal (which is an issue I've encountered on neglected bikes using quality crank removers).
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Jun 2, 2023 04:37
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bicievino posted:I've got square taper cranks on two of my bikes that are literally over 50 years old. I grease the spindle/crank interface every time I overhaul the bb because that's what the manufacturer recommends. Rene Herse would agree that crank construction is relevant: https://www.renehersecycles.com/to-grease-or-not-to-grease/
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Jun 2, 2023 04:39
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beauties. Maybe splitting cranks is more of an issue with less refined manufacturers.
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Friend reported his single speed was making a horrible clicking noise when pedaling and had snapped a link in the chain. Upon inspection the entire (cartridge) bottom bracket had migrated about an inch to the right - drive side unscrewing, NDS disappearing into the BB shell. Never seen that happen before. Then, with the bottom bracket correctly seated and a new chain, there was still clicking while pedaling under load. Turned out that when the old chain broke due to the hosed up chainline, it slightly bent one tooth of the freewheel! What a mess.
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Jun 16, 2023 17:31
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I don’t see why you couldn’t adapt the flat mount brakes with a post mount adapter, and then adapt the post mount adapter to IS (side bolts)… would just need to confirm rotor size would work after all that.
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Jul 12, 2023 20:35
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kimbo305 posted:This is something TRP takes pains to stress -- Hy/Rd has automatic advancing of the pistons to maintain pad gap. I’ve never used HY/RDs but this is good to know if I ever do, thanks! And yeah, adapters always seem to come with potential issues…
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Jul 13, 2023 17:08
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one of these guys can help recover threads that are totally hosed, best for axles where it isn’t the part under load but just preventing you from getting the nut to where it needs to be. https://www.testequipmentdepot.com/general-tools-177-8-metric-thread-repair-file-75-10-125-15-175-20-25-30-mm-threads.html
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Sep 8, 2023 18:54
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| # ¿ Apr 26, 2024 23:27 |
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I like the WTB Rocket in wide. Bonus is that it is quite affordable too.
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Feb 23, 2024 15:19
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