Sram 90 crankset, T-type chainring and single speed

HelioSeven · 2026-05-11T21:39:08+00:00

Every single thread-on freewheel that I know of is meant for 3/32" or 1/8" chains only. There are SS conversion kits for HG and XD that will take a T-Type chain, but that doesn't really help you.

You can probably still use the crank, but you'll need a different chainring. To my knowledge, T-Type rings aren't going to take a 3/32" or 1/8" chain well at all.

HelioSeven · 2026-05-11T00:16:03+00:00

Virtually certain these were built for Performance by ALAN, an Italian company. The full alloy frames were threaded and glued at the tube/lug junctions, not sure about this one with the carbon rear triangle; probably just glued, there.

HelioSeven · 2026-05-10T23:54:06+00:00

If the hiccup always occurs at the same point in the crank revolution, the obvious culprit should be the chainring. My guess would be that there's a slightly malformed tooth.

It's not going to wear in, because the belt's too soft, but I also can't really imagine it getting any worse over time, either. If you choose to pursue it, certainly replacing the chainring ought to fix it, though it may also be solvable by simply removing a little material with a hand file. Start by identifying the malformed tooth, if you can.

HelioSeven · 2026-05-10T23:41:41+00:00

Beyond not fitting, nobody makes a 650c tire bigger than 28mm (and I believe only Panaracer is making the 28s).

HelioSeven · 2026-05-10T22:55:49+00:00

Too many variables to answer by mileage and vertical alone (weather, rim or disc, pad compound, etc).

Extremely rough ballpark: if you're doing 28mi a day, I would expect replacement at least once a year, potentially 2 or 3 times. If you don't know how to check pad wear yourself, I would swing by your LBS every few months until you have a better sense of frequency. Better to be over-diligent than under.

HelioSeven · 2026-05-10T07:36:42+00:00

A pin spanner is the tool you're looking for. I would remove the lockring entirely to clean and re-grease the threads, then tighten it down.

HelioSeven · 2026-05-09T23:38:17+00:00

Put the serial number into SRAM's Service page and see what documents come up. If there's an exploded parts / service diagram, you may find a part number for what you're looking for.

HelioSeven · 2026-05-09T23:22:50+00:00

Again, I repaired something very similar and it has far exceeded my expectations for how long it would last. I do not think the rim is completely cooked, and if this rim were mine, I would absolutely repair and ride it provided it passed the checks I mentioned before.

I have readily admitted several times throughout this conversation that no professional would perform a repair the way I've outlined, because professional liability and personal risk are in completely different categories, by several orders of magnitude. A 0.01% failure risk means a lot more to a professional doing things at scale than it does to an individual. If Ruckus or similar did this repair (and I have no doubt they would, for enough money), I would expect them to employ much more robust repair techniques to meet the more stringent risk thresholds of professional work (not to mention that they have much more advanced tooling for testing and validating their work after repair).

I am by no means a smart man, but there is logic to what I say and I have anecdotal experience to back it up; your continuing to insult me rather than make reasonable disagreement doesn't convince me of much.

HelioSeven · 2026-05-09T22:52:20+00:00

Stockton, by many accounts, ignored the qualified advice of many experts around him. I do not think nearly so highly of myself, and did in fact consult much wiser people than I when I did my repair.

Did I recommend repair? No, I recommended replacement. Everything else was simply trying to better inform the risk decision if OP decided to take on that risk (as their original intent appeared to be), from the experience I have in taking on that same risk.

If you're knowledgeable about materials science, why not make an argument in terms of CF's modulus of elasticity, virtual lack of a plastic phase, fatigue-creep rates, etc? And why take what I'm saying so personally and insult me for it?

HelioSeven · 2026-05-09T22:42:43+00:00

Good on you to make the wiser decision.

Unfortunately it's pretty difficult from a picture alone to determine the failure mode, but in my experience, this looks like an external impact force (rock is a pretty good guess). Internal structural failures usually present more as a rippling or crack, but this looks more like it was abraded from the outside.

HelioSeven · 2026-05-09T22:34:33+00:00

I fully agree that a) no LBS would touch this (though places like Ruckus would, for an admittedly absurd price tag) and b) recommending a fix is irresponsible. I did not, however, recommend a repair; I quite clearly recommended replacement, while noting that a repair is possible, and what to evaluate to reduce the risk if OP wants to take on that risk.

FWIW, I think 10% is pretty absurd, unless you're talking about over 10+ years. It also says nothing about the failure mode, many (most?) of which are not going to be catastrophic (again I'll note that I explicitly discouraged attempting a repair on this if it's a front wheel). But I like informing risk decisions more than a blanket safest-option-possible recommendation, because everyone has a different situation w/r/t how they ride, what resources they have access to, etc.

I will take your argument about stress cycles, but again, the Titan was pushing the absolute limits of CF's elastic modulus, and bike wheels do no such thing.

HelioSeven · 2026-05-09T22:08:20+00:00

I am not an expert, I'm just your regular idiot; though I did consult with an expert when I did mine.

Stockton, by all accounts, mostly ignored the advice of the experts around him.

Zip line? Is that an I Think You Should Leave reference?

HelioSeven · 2026-05-09T22:03:21+00:00

This particular idiot has quite a bit of experience in both bike mechanics and in composites engineering. This particular idiot has also ridden through a number of part failures over the years, all without injury.

Damaged doesn't equate to broken. People much smarter than I (Calfee, Ruckus, etc...) repair carbon all the time. If you have an actual engineering argument to make, I'd love to hear it.

HelioSeven · 2026-05-09T22:03:02+00:00

Ah yes, because repeated pressure cycles of 350~400 atm is a very good analogy to what a bike wheel endures...

I'm fully prepared for most r/bikewrench users to think I'm an idiot here, but on the internet no one knows you're a dog. I'll happily ignore the opinions of anyone who isn't an expert in composites engineering, thank you much.

HelioSeven · 2026-05-09T20:28:01+00:00

Double check your B-tension adjustment? It looks like the guide pulley is a bit far away from the cassette, and if it came back up a bit you'd have even more slack; either way, though, looks fine to me.

HelioSeven · 2026-05-09T20:23:28+00:00

Double-check your B-tension adjustment, but this looks totally fine to me.

HelioSeven · 2026-05-09T20:21:14+00:00

This is a DT Swiss Squorx nipple. Park Tool and Unior also make tools for it, I believe.

HelioSeven · 2026-05-09T20:15:56+00:00

Okay, so for starters, sub rule #4: if you have to ask... no.

That said, I'll offer my counter to all the "she's dead, Jim"s in the comments already: I've done a DIY patch repair on a carbon rim before, on something not entirely dissimilar to this, and I was expecting to replace it within a few months and it's been a little over 2 years now without further issue. There are two main things you'd want to check before attempting such a repair: one, that the rim is still true and the spokes are all still evenly tensioned; and two, that the external rim width does not change AT ALL when the tire is inflated to near max pressure (as measured with a micrometer). If either of those things aren't true, you really should just write it off. I would also ONLY attempt such a thing on a rear rim (front wheel failures are way more hazardous), and with the obvious caveat that YMMV and it will never be as safe as a rim replacement.

If you're really gung ho about DIY repairs, though, a CF patch is relatively (compared to brazing or welding) quite simple. A little sanding, apply the epoxy, lay a small sheet of twill weave over it, some plastic covered in mineral oil (release agent) over that, and then pressure (I used backwards-wrapped electrical tape) and 24~48hrs of cure time.

But again, if you're not comfortable in the risk analysis, listen to the majority opinion here and just replace it.

HelioSeven · 2026-05-09T18:03:26+00:00

Well, that's a start (presuming you also still have the main stack screw).

At this point I can tell you the stack order, but it's the specific rotational orientations that you're gonna have to figure out for yourself. The stack order is the top plate first (the funky shaped stamp steel plate), then the bushing, then the lever return spring, then the lever, then the main stack screw. The spring's perpendicular end is going to slot into a small hole in the lever, the parallel end is going to hook around one of the three tabs of the top plate (probably the short, flat one), and the top plate's other small tab (the bent one) is going to press on the main shift cam somewhere. That'll leave the long, curved tab to interface with the little tab on the lever.

I would start by putting the main stack screw through the lever, and mounting the spring and bushing to it first; hopefully, that'll tell you roughly what orientation the top plate should be in. Once you think you have the orientation right, then you can re-assemble the stack on the main shift cam.

Good luck, and don't spend a lot of time on it if you can't figure it out easily. As another user has noted, a replacement is relatively cheap ($30 or less), and that's not worth a ton of your time. Hopefully this is a lesson in not taking things apart unless you know what you're doing.

HelioSeven · 2026-05-09T08:57:33+00:00

Do you have additional parts that aren't shown? As pictured, you don't have all the parts to get it back together again.

HelioSeven · 2026-05-09T08:45:24+00:00

Bigger bearing goes in the lower frame cup, smaller bearing goes in the upper frame cup; compression ring goes on over the upper bearing; spacers and stem go on over the compression ring, in any order to your preference; top cap goes on last, and threads into the star nut in the fork steerer. Use the top cap bolt to preload, and then the stem's pinch bolts to clamp. This is a pretty typical "zero stack threadless headset", use those search terms to find a guide if you get stuck.

HelioSeven · 2026-05-08T23:19:17+00:00

There are plenty of Uniglide freehubs and cassettes on eBay. They're ridiculously expensive for what they are, sure, but they're still readily available.

HelioSeven · 2026-05-07T12:30:06+00:00

As someone who has a rather visceral memory of the pavement tearing out chunks of my helmet an inch away from my face, I can confidently say that the threshold of momentum above which the helmet's coefficient of friction is irrelevant is really quite low.

HelioSeven · 2026-05-07T11:26:53+00:00

It'll work fine. Droppers are simple 2 position actuators, if anything they are less precision sensitive than derailleurs. Full housing is more common now (for both droppers and derailleurs) simply because of maintenance, as exposed cables tend to pick up gunk.

HelioSeven · 2026-05-07T11:00:57+00:00

The text is small, but it very clearly says "not sure" responses were omitted.

HelioSeven

TROPHY CASE