Hello Vital MTB Visitor,
We’re conducting a survey and would appreciate your input. Your answers will help Vital and the MTB industry better understand what riders like you want. Survey results will be used to recognize top brands. Make your voice heard!
Five lucky people will be selected at random to win a Vital MTB t-shirt.
Thanks in advance,
The Vital MTB Crew
I dont know if this is exactly the place for this but I cannot find any info about this. People mention that these gearbox belted drivetrains feel inefficient in some scenarios because of the belt and gears. Why do we use belts and not a chain for this? As well, why do people say the inefficiencies are greater in some gears than others? Id appreciate an explanation.
In general the comments about gearboxes themselves get comments about inefficiencies. Whichever way you spin it, there are more bearings and seals involved with a gearbox plus a plethora of gear pairs (either loaded or unloaded) which all add to additional drag. In the case of Rohloff you have planetary gears (lots and lots of bearings and gears) while Pinion is quite a lot simpler. Still in that case you have a 2-stage geared gearbox, either a 3x3, 3x4 or a 3x6 layout (for 9, 12 or 18 speed variants) where you at least have to support the input, the intermediate and the output shafts with bearings, seal everything and have all the gears constantly meshed (there are selectors engaging the 2 gear pairs giving you a final drive ratio) plus you're sloshing around oil.
While smooth, maintenance free, compact, etc., it also increases drag, no matter how efficient it is all done. Standard cassette-sprocket-chain drivetrains are, for better or for worse REALLY efficient and really well optimized in this day and age.
As for belts, I guess some more drag could be present, partly from a higher tension required to make it run (as mentioned by a few people here on the forums) and another factor would be the fact that it's rubber, which means meshing with the drive rings will inherently have more friction associated with it compared to a chain. The benefit is everything else (movement of the belt, what we call chain slap with standard drivetrains) will be muted as the fact it's made form rubber also means it's damped a lot better, it's less noisy, etc.
This is all generalisation, I don't have experience with either gearboxes or belt drivetrains...
Carbon
and maybe new saint or xtr stuff as well?
Like Mondraker with the current Summum..."AL ist the best and allows better performance"...Carbon version released just 10 months later :D
Soooooo it's a linkage driven four bar? Are there any more single pivots on the WCDH now? With the nukeproof dissent gone, that leaves just the session, right?
Isn't the Canyon proto also a split pivot?
EDIT: looking at pictures of it it is also linkage driven, there's a BB concentric rocker (similar to the Norco Range) but then a driving link and another rocker mounted in front of the BB to drive the shock. Something along the lines of what Knolly does.
what do we have here 👀
Check out Poirot over here!
Fine detective work sir. It's not like we haven't been talking about it for the last 10 pages.
My understanding is that the orientation of the piggy back has no effect on performance, so it is just a matter of fitment and appearance.
Now that it's been posted, does anyone else think that it's kinda weird that frameworks are pretty much the sole tester of the fox neo stuff? Also, if it doesn't have the HSC/HSR because its the same damper as the other neo shocks, will it still be called the Float X2?
1. NICE! 2. I see a letter from DW coming to someone soon.
clever.
Thank you for the explanation. Im kind of incapable of imagining these gear boxes without taking it apart myself or seeing a really well done exploded diagram. All of that made sense though. Primoz saves the day again
the 2 references the twin tube damper not adjustments. At least that's how it was explained to me. The dpx2 was twin tube as well, which is why some people felt it was a step back releasing the float x.
I used to ride moto with an engineer that worked on gearboxes for a major bike manufacturer. At that time, I had just begun mountain biking and didn't pay much attention to all of the tech.
But I remember him telling me that although there were many real advantages to gearboxes, it simply wasn't possible to improve the efficiency to cassette like levels as gearboxes, by design, would always have more friction as a consequence of the gears meshing, turning clusters, oil, extra bearings and seals.
I'm sure some additional optimization will occur in time but to make a gearbox as efficient as a cassette, well it wouldn't be a gearbox any longer by definition.
What appeals to me, is the micro cassette/ chain/ derailleur in a box in the BB area. I think this makes the most sense when we are working with a 1/4 hp at most and as much power as possible has to make it to the rear wheel.
As far as e-bikes however, that's a different beast when it comes to gearboxes, although at this time I still would not own one.
re: derailleur in a can, found @Dave_Camp's dc special video from 2007 or 8 maybe? (it may be blocked in some countries due to my using destiny's child or ciara or tlc or someone as the background music LOL. if no one can see it, i'll try to get rid of the music)
I know that some people might disagree with me on this, but Trek is still using a single pivot lay out. The concentric pivot at the axle doesn't change that. Saracen still make a single pivot, but I don't know if anyone is riding them In the wcdh anymore, probably not. Orbeas new DH bike will probably be a single pivot, same as the trek, concentric axle pivot.
From my understanding, belt is actually more efficient than a chain. Due to less friction, no moving parts and sh!t.
The forementioned drag comes from the gearbox. That said, it's really overblown on the internet. I'd say there's more drag in a regular drivetrain at the end of a big ride, assuming I cleaned and lubed it before.
Is this it? Cawbofaaibeuh Mondwakeuh?
Have you ever held a belt, and flexed it? Even a car engine belt? Belts absolutely have more friction than a chain, it's not even close really.
I can't speak for every locale, but I could ride my waxed chains with no maintenance at all in my dry dusty location for 100+ miles with zero change in friction or performance.
Agree. While I love the idea of ditching the derailleur, gearbox/belt driven drivetrains are measurably less efficient (even when accounting for a chain drive that isn't perfectly clean). This isn't up for debate, it's a fact.
Just to clarify, that's the gearbox's fault, not the belt.
Above 150W or so, belts are more efficient than chains as long as they have proper tension.
The belt vs chain efficiency difference is negligible once you throw the 5-10% power loss from a gearbox into the mix.
The derailleur in a box might work for DH, but not for anything that has to be pedalled. There's not enough range and you're not putting a 50T cassette inside your frame.
I mentioned this in the gearbox thread, but 2 cassettes back to back would actually work. And it's been tried in the past actually, though not to much success:
https://www.bikeradar.com/news/first-look-phaser-gearbox
https://www.sicklines.com/2007/03/19/phaser-gearbox/
A setup like this would give REALLY smooth gear ratios. And 11-25T cassettes mounted oppositely would give just over 500 % range.
The whole gearbox/belt moment right now is solely due to a massive decline in sponsorship of the traditional bike industry. Gates has been huge enough for decades to make their pitch… Shimano and Sram clearly aren’t capitalized well enough to fight them anymore, due to poor pandemic vision and blowing so much money on useless electronics, but the science on belts v chains is pretty clear. Belts suck for the low power applications we see in cycling, and they are super duper draggy, and generally horrible to live with.
Anyone who has ever worked on any belt driven bicycle will tell you how much better chains are at every junction.
Gates could do a hell of a lot more for the health of mtb racing by giving out free hoses for the excavators to trailbuilders so we can build your local trails better than splashing out a little bit over one product manager’s yearly salary in hopes of a world cup win, but clearly Gates aren’t interested in supporting the growth of mountain biking as much as they are hoping to grow a market segment that has been a failure to launch for more than a decade.
Chains are amazing. No belt can ever match the performance of modern chains and cogs.
I feel a lot of people that would complain about the gearbox efficiency making a perceivable difference to their enduro or all mountain ride would be the same people with overbuilt wheels, fox 38, cushycores, and downhill casing tires for multiple blues a maybe a black diamond trail for their saturday ride. Then finish it off with pounding back 4 IPAs and some cake later that day.
I love cake.