MTB Tech Rumors and Innovation

Another little look at the new Transition Regulator from MBR's Super Deluxe Ultimate review.  JPEG's name is "MBR-10-02-2025-Transition-Regulator-CX-35-e1741078913365.jpg"

Can someone explain how this is more efficient than just a regular idler? Regular idler is 1 chain with 5 cogs to bend around. This is 6 cogs and an extra chain. I don't understand it. 

Not an engineer but I assume it’s still less bends/contact points on the big primary chain. Since the smaller chain is fixed I doubt it creates much drag. That being said I would think the bigger advantage is on the descents where you are essentially removing the chain growth that makes idlers necessary in the first place. 

To me, the advantage is in the separation of the chain to the pedal kick. The rear end would essentially feel chain-less. This will change the anti squat a bit also.

Personally I’ve never really worried much about idler efficiency on a high pivot bike, if it’s clean I never thought it was an issue. But I also don’t live in an area with mud.

Technically, I guess you'd mainly calculate the total angle the links make when circulating through the drivetrain. That's why roadies buy expensive, large pulleys for their derailleurs and why some HP frames employ fairly large idlers. Also, it might be possible to reduce chain skew

Would be great if they made it backwards compatible, ie you could fit it in the same bike as a hpr50. I ride a fuel exe and it's such a great handling bike, a little more grunt on the climbs would be ace though!

The primary source of friction in chain drives (cross chaining aside) is the links rotating as they enter each chain ring. The larger the degree that the rotate, the more friction there is. Larger chain rings equate to less friction because the chain links don't have to rotate as much. The amount of chain actually in contact with the chain ring does not matter because it's static relative to the chain ring. For example, on a 36T chain ring each link has to rotate 10 degrees relative to the adjacent link as it enters the chain ring. Meanwhile, on a 24T chain ring each link has to rotate 15 degrees which results in more drag. In the case of this bike, the idler appears to be a 16T idler. By doubling up the number of chains at the idler position, you'd need to have a 32T there to have identical drag. 

The difference for this system is that the lower span of chain will not be stretched out as the suspension extends, this will keep the derailleur cage from swinging around which might make the bike quieter (or it might make it louder because the lower span of chain is closer to the chainstay). If shorter cage derailleurs were available (only on XTR these days I think) those could potentially be used with this idler set-up.

The efficiency and pedal kickback will be basicaly the same for both systems (yes, there might be some differences due to chain wrap, but insignificant especially with a well maintained chain).

The biggest differences in this instance are that the idler size has changed dramatically, and it looks like the idlers aren't the same size which would put you in a diffferent rear cog for the same gear inches. These will effect antisquat and chain growth of the all important tension segment. 

Spotted on Insta;

Now that the picture is clear, seeing the setup key and knurled ring makes me think, no B screw?

Why the down votes? The Commencal has a pivot on the chainstay in front of the rear axle. The whole point of putting the pivot there is to control how much the member that the brake mount is on, the seatstay, rotates (or doesn't rotate) during compression. Else why put it there? Putting it on the seatstay would make the brake mount attached to the chainstay, and this reduces the number of pivots on the chainstay, making it simplier/easier to tune rear end flex. Having a pivot there was intentional, and that pivot is referred to as the Horst Link. The same can be said of the Atherton bike (original), which is also  a 6 bar. 

I bring this up because even simpler, true 4 bar designs that we think of more traditionally being a Horst Link like Cube have still experimented with a floating brake, defeating the whole point of the Horst Link. 

Horst Link is the name for the whole package, not the pivot on the chainstay

Yes, Track cycling pioneered big chainrings (think 60+ tooth chainring paired with larger cogs 14-17t) around 2008-2010 for sprinting and slowly other track discipline followed and road TT and hit mainstream when the strong road TT guys started having a crack at the modernized Hour record around 2014-15 and onwards. 

Also, there is a short cage XT derailleur RD-M8100-GS for 10-45t cassette and i just learned via email that Madrone will have a short cage option for 10-45t cassette for their Jab derailleur that they are planning to ship late April.

Definitely no B-screw, it‘s Transmission after all. 
Looks nice! 

It is mechanical Transmission. I'm told the setup process is essentially the same as electronic Transmission. The shifter is visually very different from existing SRAM mechanical shifters -- much boxier, kinda reminiscent of some of TRP's designs. I also hear that it shifts very, very well. 

On a separate post by the guy that made that bike, he said just riding the bike around and climbing, he feels like it's more efficient and less drag than the standard idler setup.  

What do we have here? 

XS-1270 Eagle Transmission Cassette | CS-XS-1270-A1 | SRAM

10-52t compatible with an HG driver body, huh? Mech Tranny release imminent?

For those that never leave the tech rumours page

https://www.vitalmtb.com/features/great-minds-think-alike-ratio-compone…

565g oof.

I have heard through the crab vine that mech trans & Motive brakes will be released at the end of the month.
New Rockshox wireless dropper will one up Wolf Tooth's 242mm drop length and with no hydraulics at all, just air

Just speculation though, crabs are quite difficult to understand

Was this posted? 

As @Digit Bikes mentioned, having one or two chains makes no difference. With an idler the chain is taught all the way over it and adds (significant) drag going on and going off the idler. With two chains this is separated and each chain adds drag only once (BB to jackshaft going off the top chainring, jackshaft to rear wheel going on the chainring). 

Essentially it's the same situation, benefits, as mentioned, are packaging (you essentially rotate the whole driveline compared to having it around the BB, might come in handy, depending on the rear frame layout) and setups like these usually use rings much larger than the size of idler used by high pivot bikes. 

Too bad Dave Weagle patented it... You could make a semi draggy setup with a par of 22t or 24t rings for the first loop, adjust the gear ratio by offsetting the number of teeth on either ring and have a fixed output ring. You'd get different gear ranges but no change in chain length, position, changes in antisquat, etc. And the pivot could be reasonably low for a high pivot if you went really compact. 

Remember Lal Supre Drive? It only ever reached the Nicolai Nucleon 16 Supre, but that partnership was stopped last year.

The Lal Bikes guys are now moving in a new direction and developing a steel/carbon frame built around their drivetrain. They hope this proves their drivetrain to the world, and that more manufacturers will show interest.

This is a screenshot from their latest Instagram reel (6th March).

Dog it's not even the 6th here.

I appreciate what they are trying to do, for the people who just won't get a gearbox instead.

However, this does require rethinking the frame and derailleur, and if I'm doing that, I'd like to see some more significant changes. For instance, why have the tensioner where the derailleur is? It may have not mattered when a derailleur was invented and we didn't know about suspension, but nowadays it'd make much more sense to have the tensioner on the sprung part of a bike if we just have to keep the shifting at the wheel. That way the tensioner wouldn't be as affected by unsuspended hits and be much more capable of keeping the chain tight, while the rear would only take care of the shifting, not tension.

But then again it's all just a workaround for a problem that's been solved so..

The tensioner is just behind the BB, tightening the chain behind the chainring on the cranks. 

The pulley on the rear just guides the chain and enables gear selection. The way they did it enables them to use standard cassettes which makes the system much easier to make for a small company. To make a gearbox you need a lot of money. 

Right on I forgot about that, thought it was just a guide pulley behind the chainring.

Honestly, looking at the machining, shift ramps etc, I am not convinced it's the case. I think to make a good cassette and chain, which really only arrived with HG+ took a hundred years of tinkering to arrive at a slow-ass transmission. 

Meanwhile check this fella out: https://youtu.be/WRyFxQyT7h8?si=IQaRet-JDeuyNVzU His channel is worth exploring, I'm not convinced building a derailleur system in a garage in Korea would have been any easier. On the contrary, I think if gearbox manufacturing scales up, it could be much less machining than a cassette and obviously last much longer.

Clearly I'm a part of the gearbox cult, but I thought the big issue was it requires a frame designed for a gearbox. If you need to buy a new frame to get a better drivetrain, I doubt there will be enough people to care about a halfway solution when gearboxes are really bloody good these days.

And before you talk about off the shelf cassette and drag, please spend some days in Whistler or squamish outside of peak summer on a crude bike vs a box and belt and tell me what had more drag at the end of the day.

Again I appreciate what Lal is trying to do, but it's too little too late. Since gearboxes can now shift under load in a much more predictable fashion than a derailleur can dream of I doubt frame manufacturers will invest heavily into mitigating a single issue with derailleurs when the DH world just started flirting with a much more sophisticated solution. That doesn't mean it'll become "the drivetrain solution", but it just isn't time to invest heavily into something that solves half the problem.

Shift ramps and machining? The whole premise of Lal is to have Shimano do the hard work (the cassette) and them focusing on the rest. 

I'll look at the gearbox video, but looking at the disassembled case and the parts, I can assure you the guy had a few thousand euros worth of parts on his table to assemble one gearbox. Multiply that by a few samples, multiply by a few design loops to fix issues, pay yourself to be able to live while you develop it and you need probably multiples of thousands of dollars to get a product developed to a point where you can even start thinking about selling it or mass producing it. 

https://www.youtube.com/watch?v=pmNZxvmyOoI
 this is what I9 was teasing about, a refined Hydra Hub, nice to see they improved on some stuff

I'm almost certain this came up before, but maybe it was in another place.  I think he did it this way just because an idler that big would foul on the existing chainring.

And probably also "just because I could".

a product from a company you shouldn't buy from anymore