Light, Stiff, Rear, 38-40mm Deep, 23-25mm Wide, Rim Brake

[Lelandjt]

My 2016 rear Farsports 50 deep, 23 wide, Bitex hub, 24 2x CX-Rays wheel is perfect on paper but has always had enough lateral flex that I need to run the brakes pretty open and still sometimes hear rub. In addition, it's the only wheel I've ever owned that changes dish when weighted. The rim shifts to the left with my 175lb on the bike. Drive side spoke tension is maxed, non-drive side tension achieved perfect dish when unweighted, which results in 1-2mm left offset when weighted.

I want to replace it with a rim that's slightly shallower, ideally lighter, and not more than 25mm wide.

I'm willing to pay for a lighter hub so long as durability is good (DT180, Carbon-Ti, not ExtraLite), but is there a lighter cheap hub I'm not aware of?

I've always used CX-Rays or Aerolites but do I need thicker spokes on driveside? I'd like to keep it light.

I assumed 24 spokes was a good balance of weight, stiffness, and aero but do I need 28 to avoid brake rub? I thought 2x on both sides was stiffest, but should I do radial NDS? Should I consider 2:1?

Is there a complete wheel I should consider? I've always built my own or specced out a wheel and had it built by a company like Farsports or LightBicycle.

*Not interested in replacing my front Farsports 38/23, Bitex, 20 radial CX-Rays

[mrlobber]

Bracing angle is actually a more important factor for lateral wheel stability than spoke count / spoke thickness
https://blog.fairwheelbikes.com/reviews ... ub-review/

Relating to your experience, I have a shallow Farsports tubular wheelset on Bitex hubs from 2015, and the bracing angles are tiny, compared to, say, Carbon Ti, especially for the front.

Choose a solid reliable hub (not sure, if you should overpay for DT180) in the rear, Farsports or LB rims (the recent will be at least 26mm wide, but no big difference vs 25mm), and you'll be fine.

[C36]

If you are ok with a 26mm rear wheel go for the Hyper 38mm with carbon spokes. That’s roughly 20% stiffer than your traditional current set up (40N/mm versus 50).
That’s the stiffest option that currently exist , not sure about rear weight but the pair is 1210g (naked, 1260 with tape and valve)


Supersix evo2 HM - 5.9 stiff-aero version, 5.6kg light specs.

[Lelandjt]

I suspected the Bitex hub of having bad geometry since this is the only rear wheel I've had with this problem. I'm happy with Carbon-Ti hubs on an XC build I did. I'll check out the Hyper.

[BdaGhisallo]

I went through a period of having Enve rims of differing heights built into wheels and the only thing that stopped lateral flex was thicker spokes. If you want a stiff rear wheel, no matter the hub geometry, you need more material in the spokes. Give up on the CX-Rays and the Aérolites.

[Lelandjt]

I went through a period of having Enve rims of differing heights built into wheels and the only thing that stopped lateral flex was thicker spokes. If you want a stiff rear wheel, no matter the hub geometry, you need more material in the spokes. Give up on the CX-Rays and the Aérolites.

I really didn't want to hear that, but suspected it was true, at least on the drive side. I think Hyper's carbon spokes are the answer for me.

[C36]

CX-ray have been “a bad thing” for cycling. Yes they raised durability to a new level (thanks to a great work on metallurgy and production techniques) but they marketed them only on weight, at the cost of a reduced wheel stiffness and got away w/ it cause it’s difficult to rationally quantify.

Carbon spokes are the future, it’s the perfect usage for composite (pure traction efforts) if well use (not like Hunt for example, they just compensate their initial very low stiffness instead to reach higher levels).


Envoyé de mon iPad en utilisant Tapatalk

[Lelandjt]

Carbon spokes are the future, it’s the perfect usage for composite (pure tension efforts).

Did you see that LightBicycle just started making carbon spokes? This will be the beginning of them becoming common place. Just like carbon rims were rare and boutique. Once LB started making them it was only 2 years until every mid-grade bike had them.

[WorkonSunday]

does it have to 38-40mm? tune TSR 35 is very very well built with wide rims (for rim brake system). standard set is already quite light, but you can buy upgraded hub version (skyline) to reduce weight further.

my one of my bikes, i use 45mm zipp 303s and 40mm zipp 303 fc as a mix, cant really tell the height differences unless you study the decal, so i think 38mm front with 35mm back is ok as well.

[Lelandjt]

does it have to 38-40mm? tune TSR 35 is very very well built with wide rims (for rim brake system). standard set is already quite light, but you can buy upgraded hub version (skyline) to reduce weight further.

my one of my bikes, i use 45mm zipp 303s and 40mm zipp 303 fc as a mix, cant really tell the height differences unless you study the decal, so i think 38mm front with 35mm back is ok as well.

I'm not super picky about the height. I just want decent aero while manageable in strong gusty winds. I'm pickier about width because I like the lighter weight of narrower rims and I'd like to keep using 23mm tires. All the pavement I ride on this bike is glass smooth so I love the weight, aero, and feel of 23s at 115-120psi. I realize that 23mm wide rims don't really exist any more so if I get a new wheelset I'll be switching to 25mm tires, which is what I use on my non-aero bike that gets used on a wider variety of roads.
I'll look into your suggestion.

[BdaGhisallo]

Bracing angle is actually a more important factor for lateral wheel stability than spoke count / spoke thickness
https://blog.fairwheelbikes.com/reviews ... ub-review/

In my experience, this was not the case. I actually had Fairwheel build me a few sets of Enve rimmed wheels with both DT240 rubs (not great bracing angle) and White Ind T11 (much better bracing angle).

The difference in lateral stiffness between the two rear wheels with the same Aerolite spokes and the same rims was barely noticeable. What did massively improve stiffness was building the rears with thicker spokes - as in normal 14-15 DB spokes. The 240s rear wheel with the thicker spokes was very noticeably stiffer laterally than the T11s with the Aerolite spokes. It wasn't even close.

Aero doesn't matter much at all with spokes in the rear wheel so the best solution is to go with thicker spokes on rear wheel builds, unless you like a lot of brake rub, that is.

[WorkonSunday]

does it have to 38-40mm? tune TSR 35 is very very well built with wide rims (for rim brake system). standard set is already quite light, but you can buy upgraded hub version (skyline) to reduce weight further.

my one of my bikes, i use 45mm zipp 303s and 40mm zipp 303 fc as a mix, cant really tell the height differences unless you study the decal, so i think 38mm front with 35mm back is ok as well.

I'm not super picky about the height. I just want decent aero while manageable in strong gusty winds. I'm pickier about width because I like the lighter weight of narrower rims and I'd like to keep using 23mm tires. All the pavement I ride on this bike is glass smooth so I love the weight, aero, and feel of 23s at 115-120psi. I realize that 23mm wide rims don't really exist any more so if I get a new wheelset I'll be switching to 25mm tires, which is what I use on my non-aero bike that gets used on a wider variety of roads.
I'll look into your suggestion.

i think 23mm should still be ok for Tune TSR 35. HUNT sells internal width 20mm rims and stated it's ok for 23mm tyres too. of course there are some 24mm tyre options out there too.

[C36]

Carbon spokes are the future, it’s the perfect usage for composite (pure tension efforts).

Did you see that LightBicycle just started making carbon spokes? This will be the beginning of them becoming common place. Just like carbon rims were rare and boutique. Once LB started making them it was only 2 years until every mid-grade bike had them.

Yes, LB, BTLOS do offer those options that exist for carbon-spokes specific hubs or classic hubs. I saw on IG a C50 (I think) upgraded with Carbon spokes i was pushing them to run some stiffness tests to see the impact... still waiting.
Those later spokes are heavier and appear to have glued metallic inserts so durability has to be proven (over the ones seen on Hyper or Cadex where you have a mechanical stop not relying on glue)

[choochoo46]

I'm not super picky about the height. I just want decent aero while manageable in strong gusty winds. I'm pickier about width because I like the lighter weight of narrower rims and I'd like to keep using 23mm tires. All the pavement I ride on this bike is glass smooth so I love the weight, aero, and feel of 23s at 115-120psi. I realize that 23mm wide rims don't really exist any more so if I get a new wheelset I'll be switching to 25mm tires, which is what I use on my non-aero bike that gets used on a wider variety of roads.
I'll look into your suggestion.

If you like going fast you'll want a rim with an external width wider than the tire when mounted and inflated per the 105 rule. Similarly you're probably losing watts from impedence with pressures of 115-120psi unless you're riding in an indoor velodrome.

https://silca.cc/blogs/silca/part-4b-ro ... -impedance

Check out the Silca tire pressure calculator here: https://silca.cc/pages/sppc-form