XM Carbon Speed Race Frame - The wish list

[Sakizashi]

Curious to know if this project is still alive.

I was thinking about this other day, trying to figure out how to design a bayonet fork arrangement that was less proprietary, and honestly, I failed. That doesnt mean it cant be done, I just think the economics and need to reuse fork molds would make it tough to do. On the other end of the spectrum, I think it would be really hard to beat a bike that looks like the XMCS GT, but has the geometry of the Noah Fast 3.0, but with an 80mm BB and a 72.5 HTA (or 73 if you feel bold!) angle across the range. I think you could even reuse the single, existing fork from the GT and manage to get 35mm of clearance in the rear with a sub 410mm chain stay (like the LTK266DSL does).

If you wanted to go all out, a minimal A-C fork, D-shaped steerer, and headset arrangement like the 3T Strada Integrale (whatever the current version is called) would be pretty sweet. Though it would allow you to drop the BB and have more tire clearance without too short of a head tube,  I am not sure it would be worth a new fork mold.

[Macedingle]

We would get our US trademark approved soon, hopefully mid-Oct. Then we would arrange UCI approved stuff on our wheels and frameset.

Peter! If you need USA warehousing and order fulfillment message me! I manage a warehouse in East Tennessee and would love to be apart of your US growth!

[toxin]

Curious to know if this project is still alive.

I was thinking about this other day, trying to figure out how to design a bayonet fork arrangement that was less proprietary, and honestly, I failed. That doesnt mean it cant be done, I just think the economics and need to reuse fork molds would make it tough to do. On the other end of the spectrum, I think it would be really hard to beat a bike that looks like the XMCS GT, but has the geometry of the Noah Fast 3.0, but with an 80mm BB and a 72.5 HTA (or 73 if you feel bold!) angle across the range. I think you could even reuse the single, existing fork from the GT and manage to get 35mm of clearance in the rear with a sub 410mm chain stay (like the LTK266DSL does).

If you wanted to go all out, a minimal A-C fork, D-shaped steerer, and headset arrangement like the 3T Strada Integrale (whatever the current version is called) would be pretty sweet. Though it would allow you to drop the BB and have more tire clearance without too short of a head tube,  I am not sure it would be worth a new fork mold.

Was it ever actually confirmed to not just be wishful thinking from the OP?

Well what's your threshold for proprietary? Stromm have a "steerer" molded on top of the bayonet to be compatible with normal stems. But like a regular steerer, you can't add back stack, like you can with S5 and Y1RS, once it's cut.

[Vasegaard]

I’ve spoken to Peter and they are at the drawing boards regarding the frame. They were/are influenved by superX lab71

[Sakizashi]

Was it ever actually confirmed to not just be wishful thinking from the OP?

Well what's your threshold for proprietary? Stromm have a "steerer" molded on top of the bayonet to be compatible with normal stems. But like a regular steerer, you can't add back stack, like you can with S5 and Y1RS, once it's cut.

IDK, its just something I was thinking about and felt like bumping the topic to retract my wish for bayonet fork on the basis of cost and complexity. While I still love the idea of separating fork preload from the attachment of the stem and allowing for the use of many different stem/ bar systems, doing so introduces proprietary spacers, as you mention a proprietary top plate. Likely a proprietary axle/ bolt or cap(s) and expander for the steerer.

It's just a lot. You can get most of the aero using a traditional setup, trying to hide your cross-sectional area within the rider's body, and working with a more aero riding position. Sure, you give up the people who can't ride in that position, but you have the GT for them anyway. Obviously, it's not exclusive like that, but taking a risk and producing a $2400 frameset that's novel vs. a $1200 frameset that is still novel seems unnecessary for a couple of watts saved in a wind tunnel test.

[toxin]

Yeah, that's most of the thinking behind my wish for no bayonet earlier in the thread. I just don't see a feasible way to make a proper bayonet design while keeping costs and complexity acceptable for the target market.

I’ve spoken to Peter and they are at the drawing boards regarding the frame. They were/are influenved by superX lab71

You sure it wasn't systemsix or supersix?

[rsw42]

Being one of the mechanics for a bunch of youth racers: I am so incredibly happy nobody has a bike with a bayonette style fork... I'd really wish that EVERY bike (and this race bike as well) will have a ton of versatility, so you can choose in which way you gonna build it... for many of our kids internal routing through the headset would double or triple the time in the workshop... being able to get the cables out of the down tube helps a ton (and watt losses dont matter as much in the kids races)...
being able to have a huge box of stems etc without having to care for any proprietary spacers, forks etc makes the sport easier and cheaper for all of us...
and so on...

[Vasegaard]

Yeah, that's most of the thinking behind my wish for no bayonet earlier in the thread. I just don't see a feasible way to make a proper bayonet design while keeping costs and complexity acceptable for the target market.

You sure it wasn't systemsix or supersix?

They wrote superx lab71 to me. Could be a typo from their side

[aeroquest]

I join those who are asking for more aerodynamics.
I want maximum aero + 38c ground clearance + maximum frame rigidity + wide aero fork. Let it be heavy if necessary.

[BikerJens]

I just want it to come in a adult size..

[toxin]

Alright, well since this thread is active again and it's confirmed that there's at least something going on, I'll make a second round of suggestions focused on design features, with some examples.

We've already established the headtube and fork is where most of the effort should probably be spent. The most critical is reduction of frontal area, so a heavily waisted headtube would be the best in that regard. This probably means a few extra layers of M-series fibers in the headtube to shore up torsional stiffness, which I think it's an acceptable tradeoff. Examples in first picture: Stromm track bike, Cube Litening Aero, Factor Ostro V2, Dare VA-Afo.

This one can be skipped as it's relatively less impactful and invites more proprietary stuff: Finding a solution to route the cables and reduce the size of the upper headset bearing will allow for a narrower headtube. Usually this is done with non-standard steerers that allow for extra room for the cables. Scott Foil does is with a smaller, 1" diametre, eccentric steerer tube, Incolor SS with a kinked eccentric steerer and most other times it's a D-Shaped steerer. Now the Foil solution is the most elegant, but requires the use of their proprietary stems or a shim. D-shaped steerers are a potential safety risk, especially if they're used with spacers. I think they can still be okay if executed in a similar way as the EXS forks (picture 2).

Make the actual cross section of the upper part of the fork where the blades transition into the crown actually horizontal, so they're not presenting to the wind like they're trying to achieve lift. Examples from Wilier Filante ID2, Stromm Track Bike, Lapierre Xelius 25 in picture 3. Picture 4 is how Factor did this very wrong on the Hanzo TT and fixed it on the Hanzo Track.

Want to reiterate again that there really isn't much to be gained in the rear triangle. Make it as light as can be while stiff enough and make the seatstays slightly aero profiled but thin. Tarmac SL8, Supersix gen 4 and especially Stromm Raktt (picture 5) come to mind.

Don't make the downtube hug the front wheel. This is a very delicate feature that works in a wind tunnel and during steady riding in low wind conditions, but can be very inconsistent in turbulent and high yaw wind conditions. Cervelo S5 performs poorly at high yaw and I think this might be one of the reasons why.

[toxin]

So this talk about ideal bikes got me wanting to draw up a sketch of my own, for fun and on the off chance it steers XMCS in my desired direction. As with all "fun little side projects" it spiraled out of control immediately and I spent an absolutely unreasonable amount of time and effort on something I'm not getting paid for and I can absolutely see how good bikes take a lot of time and money to develop.

It's still pretty rough, the fork crown is fucked up, the fork would barely be able to turn before hitting the frame, the chainstays and downtube probably don't need to be so chunky, the seatstays are likely a cracking risk and definitely a heel interference risk, the seattube is probably a bit too thin, I'm not sure the bottom of the head tube is wide enough to safely accomodate a standard bearing and just about every tube cross section is eyeball aero. Still, I'm posting it just cause I wanna show it off.

Front end geometry is roughly in line with Dare VA-AFO, 76° seat angle (probably excessive if there's no significant setback or sliding post), 80 mm BB drop, and minimum 6mm of clearance with 40 mm tyres front and back.

[Dark17]

Name of the frame should be a homage to Chinertown since the design ideas literally came from the members.

[Requiem84]

That’s a brilliant effort.

Looks like a mix of all the cool design stuff around now. Maybe seat stays a bit too low aesthetically. Feels a bit too close to a TT bike.

[Sakizashi]

So this talk about ideal bikes got me wanting to draw up a sketch of my own, for fun and on the off chance it steers XMCS in my desired direction. As with all "fun little side projects" it spiraled out of control immediately and I spent an absolutely unreasonable amount of time on effort on something I'm not getting paid for and I can abosolutely see how good bikes take a lot of time and money to develop.

This is a fantastic effort. One of the challenges of this bike geo is that fitting a 40mm WAM tire AND having 80mm BB drop is going to be hard in the small sizes due to really short HT lengths. If you went back down to a 35mm tire size with 6mm of clearance, you could make a low crown fork like 3T does and make it all work.

For my contribution, I tried to create a fictional geo chart for this bike that could roughly go with Toxin's design.

• I based it more on the Noah Fast 3.0 than the Dare, because there are enough video of pro riders on the Noah Fast 3.0 to see how their bikes are set up and ridden which allowed me to tweak that geometry a bit to balance the bike a bit better under the massive assumption that the pro riders from UNO X are the target market for a frame like this.
• This assumption that Peter's dream is to get a bike in World Tour level races is foundational to this geometry chart. Problems with the UCI rules on the horizontal front-center distance (ARTICLE 1.3.016) were a key challenge when working on the geometry
• In an effort to keep costs under control, I worked to find a single fork rake and HTA that worked for the range. The bike would be one-piece molded, so I felt free to adjust the rear triangle as needed.

The attached image shows what a geo chart could look like if you wanted to design a breakaway, specialist aero bike, learning from the Noah Fast 3.0 pro fits and still be UCI-compliant. This is not just a copy of an existing geo, nor is it an attempt to linearly scale a bike from a winning formula (e.g., the VB 368 scaling its entire range from the Size 52 SL8). It's definitely rough, but hopefully fun for discussion.

PS. I didn't check the ST C-C as it doesn't drive anything in the spreadsheet so its the same as it would have been for the Noah Fast 3.0