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TheSuspensionLabNZ Liked a reply to forum topic MTB Tech Rumors and Innovation
2/12/2025 3:18pm
That might not be a stupid idea. I've felt for a long time that problems with chain slap or chain drops have been related to the bouncing of the lower section of chain, and the current clutch derailleurs are a pretty blunt method of fixing it which isn't ideal. The digressive nature of using friction to stop the pulley means when it overcomes that breakaway force the chain will slap mega hard, so a more progressive damping system might be better and wouldn't add friction the suspension. This might be a slightly crude way of doing that, but I can...
This forum topic has 30444 replies.
Roryb Added a reply to MTB Frame Compliance Analysis & Discussion
2/12/2025 3:15pm The more you learn, the more you realize how little you know.
juliusk Liked a reply to forum topic MTB Tech Rumors and Innovation
2/10/2025 7:54am
I have it in combination with a dorado (not the carbon one) so in theory a super heavy front end. The first two runs I felt it being a bit heavier, but after that you‘re used to it. But honestly there has never been a moment where I felt like it‘s too heavy to do whatever, the bike is like 19 kg+ so that‘s heavy as a whole. It‘s rather extreme that, if I take the Tmd off now, the bike actually feels terrible in comparison and I‘m wondering how I could ride it before😅
This forum topic has 30444 replies.
Roryb Added a reply to MTB Tech Rumors and Innovation
2/9/2025 3:05pm The weight on your headtube is very noticeable though when pulling up the front wheel? I swap between a Dorado and a 180mm mezzer on the same bike. The weight difference is about 1kg. The Dorado is way smoother and eats the rough better at the cost of front end weight which is quite noticeable. I assume the same would...
Roryb Added a reply to MTB Tech Rumors and Innovation
2/9/2025 10:43am Yes, we use mass dampers to control wind accelerations in skyscrapers. They are basic shake weights suspended on springs. Slosh tanks are often used too. These are purely for occupancy comfort. They can be used for strength design but then they need to be active dampers to react to all frequencies. Because if this, they are rarely used for strength...
Roryb Added a reply to The Belt Drive and Gearbox thread
2/8/2025 3:27pm For racing, it's never really the bike, it's the rider and feeling comfortable on the bike. People win without drivetrains, on dry tires in the mud etc. Roczen is kicking ass on a 10 year old Suzuki with a Kickstarter... None of that has anything to do with what's an improvement mechanically though.
Roryb Added a reply to The Belt Drive and Gearbox thread
2/5/2025 7:00pm Effigear run a fixed rear hub so the chains always spinning. WRP have a similar system with a crank based freewheel. These likely work well on clean fresh chains and get worse from there. You could probably do the same on the pinion as it has a freewheel up front but it would suck for rolling speed. There's no reason...
Roryb Added a reply to The Belt Drive and Gearbox thread
1/17/2025 3:15pm Yeah, I think yours with the chain close to CS and lower tensioner up high, takes out most of the chain feedback. Proved if it feels chain less. That's the real test. Another thing I noticed hopping back and forth form belt to chain is the lateral chain movement and associated noise/feedback. Perhaps a fresh chain would reduce this. The...
Roryb Added a reply to The Belt Drive and Gearbox thread
1/17/2025 12:19pm Regarding pedal kickback comment with belt; I use the term pedal kickback as that's what people refer to when taking about pedal feedback. I am of the strong opinion that it's pedal feedback, not kickback that's the main issue. Unless you are locked up on the brakes, your rear wheel is spinning too fast to catch. The very low belt...
Roryb Added a comment about bike check Vessel Pinion GearBox-200 V1
1/16/2025 12:50pm
Rad. The DT/shock/BB area is wild
Votes:
This bike check has 7 comments.
Roryb Added a reply to The Belt Drive and Gearbox thread
1/16/2025 10:15am People assume way too much about gearboxes and belts. Do not judge until your ride one. The reports you read about the drag or gripshift appear to be mostly from people who haven't ridden a gearbox bike and are just repeating what they heard. I have a gearbox bike with a belt drive, 155mm cranks. Full suspension with idler and...
carlinojoevideo Liked a reply to forum topic MTB Compliance Analysis: Danny Hart's Modified GT Fury Frame
1/7/2025 5:44pm
I did a seatstay brace test last week on a full steel downhill bike. I just did a run with the brace and without. The above graphs are without the brace. This is just a visual to show the difference between rear axle to BB. To get the % change, I just the Excel files through a program and separate left and right accelerations. In this case, without the bridge, the rear axle moved laterally 6% more and had 20% more torsional twistng. The conditions were super dry so I feel that the added compliance gave me more grip and...
This forum topic has 24 replies.
DMcMullan Liked a reply to forum topic MTB Compliance Analysis: Danny Hart's Modified GT Fury Frame
1/7/2025 5:44pm
Hi Ryan, Great job validating my work! It’s really cool to see the numbers backing up the theory. Ideally, we would have done the 3D modifications and FEA first, then created the frame or modifications to match. Unfortunately, that wasn’t an option as I didn’t have access to the 3D tools or enough time. The first modification was done at Val di Sole. The track was super wet and rooty, and extra frame compliance and grip were needed—that’s when the hacksaw came out 😂. However, as you mentioned, modifying the link without simultaneously addressing the seat stay bridge meant the...
This forum topic has 24 replies.
Roryb Added a reply to MTB Frame Compliance Analysis & Discussion
11/23/2024 10:07pm Developed for a frame designed for trunnion mount shocks. 1 step forward, 2 steps back.
Roryb Added a comment about bike check NAF Parker, singlespeed, belt-driven, Park bike
11/22/2024 3:56pm
Hell yeah. What sprocket/cog size did you go on with? I'm trying to get a SS belt DH bike going but the front sprocket size is a concern. Also, get a snub mount for the rear cog as soon as you can. It will slip once the belt wears in and it gets wet and muddy. I got a full summer before it started to slip on me.
This bike check has 14 comments.
Roryb Added a reply to MTB Frame Compliance Analysis & Discussion
11/16/2024 11:21am I don't think the slider is the best approach. If anything it will just kill your shock quicker as it prys off your seattube. Just add a brace between the pivot and shock mount to make that stiff. My frame has a pretty tight gap from rear end to seattube (1/4") and it has never touched, even with spherical bearings...
Ryan Burney Liked a reply to forum topic MTB Frame Compliance Analysis & Discussion
11/13/2024 9:17pm
@Roryb @carlinojoevideo @ earleb you guys are freaking rad. Great work on your bikes! Hell yeah.
This forum topic has 135 replies.
carlinojoevideo Liked a reply to forum topic MTB Frame Compliance Analysis & Discussion
11/13/2024 9:16pm
Yeah the above trail was Teleonics from the upper dirt road before the "ski jump" to the parking lot. Bike set up: Steel front end(modeled after 23' Trek Session), stock aluminum rear end, Ochain, Dorado fork, DT 471 front rim 1.6 spokes, Crank bros DH carbon rear rim 1.5 spokes, CounterShox mounted on fork 800g and behind BB 600g, Conti Kryp tires 24/26psi. I only got a few runs in this day, then had a little get-off that stopped my riding for the day. So I didn't really test anything here, just trying to get some more baselines and data...
This forum topic has 135 replies.
carlinojoevideo Liked a reply to forum topic MTB Frame Compliance Analysis & Discussion
11/13/2024 5:35pm
Here is some data from riding my steel Trek in Southern California. Approx 2 minute run in Laguna. The rear axle showed 67% more lateral accelerations than the bb. (Negative is to riders left and positive is to riders right.) The rear axle showed that it twisted torsionally 35% more than the lower frame/bb. What does all this mean? Hahha, nothing really until I gather more data on the same trail, in the same conditions. But I’m starting to gather a baseline with a few frames. The problem is dirt conditions and trail style play a big load(literally) on what...
This forum topic has 135 replies.
Roryb Added a reply to MTB Frame Compliance Analysis & Discussion
11/13/2024 11:41am Yes it is all give/take. Exactly like suspension setup. This bike (The Homer) gets pedalled as an Enduro bike, Whistler laps and then Prevost shuttle laps. For enduro and Whistler laps, I think the compliance is perfect. It eats rough and softens the harsh Whistler laps. Even with the firm suspension setup I run. Prevost is another beast though. It's...