Current style derailleurs are great for road bikes, light and efficient, but a shit idea for an offroad bike.

No matter how exquisitely they are made, they are out there and vulnerable.

Surely it’s about time the whole concept was revisited for offroad bikes?

The vulnerability could be avoided if the chain tensioning mechanism was moved to the back of the big ring, then the gear selectors could be tucked up close to the chainstay at the rear, ie separate tensioning duties from selector duty.

But…

That would mean two components if I understand your suggestion, both mounted onto the frame somehow. Although I see what you mean, it would make for a heavier system and two parts that would require maintenance.

Given the cost of a new derailleur, how would that compare in manufacturing and maintenance costs do you think?

Also, Alfine/Rohlhoff. No derailleur, still not widely adopted.

No.

In other markets that are not so fashion led as our bike market hub gears are the norm on mid range and upmarket bikes with derailleurs only on lower end bikes – IE the whole euro tourer / utility bike market.

I have an SA hub on my road bike, a rohloff on the tandem and have used an alfine a lot. I far prefer them to derailleurs. NO missed shifts, no dropped chains, better chain life, cheaper over time.

Lots of companies are doing gearboxes, none of them are doing it better than current derailleurs. They’re heavy, expensive, require backing off load to shift, and worst of all, some of them require gripshift.

They’ll be the right answer in time, but not yet.

In other markets that are not so fashion led as our bike market hub gears are the norm on mid range and upmarket bikes with derailleurs only on lower end bikes – IE the whole euro tourer / utility bike market

I doubt it’s fashion led.

If there was a competitive edge to be gained from non derailleur equipped bikes, the DH WC and EWS would be all over it en masse and it would have trickled down to the weekend warrior scene.

A rear heavy hub geared touring bike makes sense . Less so for proper DH/ Trail/ Enduro riding

No.

The vulnerability could be avoided if the chain tensioning mechanism was moved to the back of the big ring, then the gear selectors could be tucked up close to the chainstay at the rear, ie separate tensioning duties from selector duty.

A bit like this ?

Like most bike innovations, it’s been done before
Osgear

Boarding bob thats the point. the needs of racers and the needs of leisure cyclists are different but in the UK we follow the pros even tho that means bikes that are not as suitable as they might be.

Thats what I mean about it being fashion led.

I’m just amazed that nobody has thought of posting this question before.

I’ve broken 1 in the last 15 years…. TBH i’m not classing that as a fail, in the slightest…

Nothing wrong with them at all.

I’m just amazed that EPICYCLO hasn’t thought of posting this question before.

FTFY

I am all for changing to gearbox long term and actually believe this is ultimately the way the market will go (outside of ebike) it’s a crazy idea having something as expensive as a rear mech inches from the ground.  I can’t imagine if there was a blank sheet of paper approach today anybody would design a rear mech on a MTB.  Ultimately though Shimano and SRAM have millions invested in groupset design, with patents and pipeline development.  Are they really going to invest in technology which limits their aftermarket sales of broken shit? Who knows, but I think a sealed gearbox unit makes perfect sense for here in the U.K.

once they make a product that is as efficient it might catch on.

it’s a crazy idea having something as expensive as a rear mech inches from the ground.

Deore derailleurs aren’t expensive and function perfectly well. If you go to the Alivio and Acera levels, they are cheaper still. You’d need to break a lot of derailleurs to pay for a gear hub.

https://www.bike-discount.de/en/buy/shimano-deore-rd-m591-sgs-9-speed-rear-derailleur-32511

Hmm. I would like to think so but until gearboxes become more mainstream/affordable for plebs like me, probably not. The (marketing led?) problem is that people think they need a bazillion ratios to ride off road with their mates at the weekend and the rear mech is already a well-polished turd that’s fairly easy to turn up to 11, or 12 or 13, and MOAR Speeedz is MOAR Beetererer!!11!1!!

Give me a five speed, light-ish gearbox please.

Gearboxes are shockingly bad on bikes, heavy, draggy, expensive, not repairable trailside, sloppy and with terrible ergonomics. Whereas derailleurs are the opposite.

So, no.

Hols – don’t forget the saving on chains, cassettes and chainrings.

My rohloff on the tandem is now saving me money every year as the high initial cost has now been overtaken by the saving from less replacement parts.

£1000 to have it on the bike. Saves well over a hundred a year in less consumables. I think 7 years was the tipping point when it becomes cheaper ie over 7 years the £1000 cost has been offset by the annual savings in consumables

it’s a crazy idea having something as expensive as a rear mech inches from the ground.

This was the real reason behind the move to 650/29” wheels instead of those derailleur breaking 26” ones. Gets the mech further from the rocks.
😉

Have gearboxes / hub gears had their day might be a more relevant question?

Derailleurs are remarkably robust, reliable and efficient IME.

I had an Alfine commuter and it was horrible, squidgy pedalling in some gears, draggy, heavy with all the weight at the back, faffy set up, proper PITA taking wheel out and reinstalling.
Rear mechs last a good few years and cost £50 tops, smashing them into things so they break is quite rare.

Pretty much my experience as well (On-One Pompetamine with Alfine 11), I might have had a duff unit but it never seemed “right” despite wanting to get on with it as the idea is great for commuting.

No matter how exquisitely they are made, they are out there and vulnerable.

I will say that with the current fashion for single ring/1x drivetrains, we seem to have forgotten a lot of fundamental principals that we would have sworn by a few years ago. Rear mechs are no longer exquisitely made, and are actually being made MORE vulnerable.

Remember when DH racers were using road derailleurs as they were smaller and tighter to the frame? Now we’re using gopping great 1x derailleurs which are bigger, more expensive and hang lower than anything we used in the past.

Remember when increasing the (unsprung) weight of a rear wheel was considered a bad thing? Now we’re moving as much of the transmission to the rear wheel as possible, bigger mechs, bigger cassettes etc.

I’m looking at new GRX equipped gravel bikes and one of the things which really stands out is that they all have bigger rear mechs than I ever used to run on my XC mountainbikes!

Last time I broke a rear mech was 1999.
They are very efficient, reliable & cheap (if you chose them to be).

A Rohloff looks to be about £1k for the hub alone – so how much for a wheelbuild? £1200?
How many people are going to look at bikes in a bike shop & spank an extra £1000 on a bike that has a hub gear?
They are very much a product for a minority of users, IMO.

stumpy – as above – after 7 years you are saving money as drivetrain parts last a lot longer and are much cheaper to replace. HIgh initial cost for lower running costs

I was thinking about this the other day, if somebody could build a lightweight hydraulic drive system which also controlled the gearing it would be pretty cool as you could do away with everything external that wears, chain, chainrings, cassette, mechs etc

In reality it would probably cost a fortune and there’s nothing really wrong with things as they are, think I’ve only ever broken one rear mech in my life!

35 yrs of riding (crashing) a mountain bike. Broken a mech once.

They work, they are simple, they are light.

Other alternatives are a solution to a problem that just does not exist in the real world. Which is why they have not caught on. No one racing Enduro, XC or DH is asking for an alternative.

As scotroutes well knows, my opinion of mtb derailleurs is scathing. Delicate, expensive consumables in a vulnerable position.

But the question isn’t about gearboxes, hubgears, or even singlespeeds. Their advantages are obvious, as are their drawbacks, but they don’t fail because of exposure to trail hazards, careless stowage, or a fall on the “wrong” side, and they generally last the life of the bike.

As rusty90’s Osgear picture shows, a derailleur does not have to have a dangly bit at the rear. (I have an Osgear in my collection of derailleurs).

The Osgear’s weakness is the dangly bit below the chainring, but that could be just as easily accommodated at the rear of the ring. I believe it was done like that for reasons of efficiency – less teeth engaged and causing friction – but for mtb use it would be safe tucked away behind the ring.

I think it was DMR who made a mtb BB chain tensioner which pulled the chain up behind the ring. Something like that might work with an Osgear type gear selector.

And of course, then I’d want the whole thing encased in a protective chaincase. 🙂

If we were all riding hub geared bikes for general moutain biking and someone “invented” a 1X Deore drivechain for £150 we’d all piss ourselves with excitement.

A basic derailer set up gets me through 2 winters with little to no maintenance. I’ve broken 1 mech in 10 years of riding, and if it happens again can be fixed cheaply and easily.

Rohloffs are lovely things and definitely have a place. For your average leisure mtb’er the derailluer does a good job for little money.

A specific frame is also required for a Rohloff, you can’t just buy a rear wheel and put it into your vertical dropout frame can you?

ALso buying a part with a 7 year return is to going to suit most people as they won’t have the same bike seven years later.

Fashion led? Hub gears are more expensive than derailleurs, even on commuter bikes and especially on higher end bikes, they are heavier and they are more draggy. I would still like to try one, but these are the reasons why they aren’t adopted more widely.

I don’t know where you lot get the idea that derailleurs are a problem. I’ve had two derailleur failures on the trail in nearly 30 years of MTBing, and even then the first one was about 4 years ago. One was poor maintenance. Mechs last me years and years. The trails are utterly filthy currently, the last four rides have been on trails with watercourses running down (I think the streams have actually diverted themselves) and a £60 mech has performed perfectly.

It’s all well and good projecting a 7 year ROI on a hub gear but that still requires you to find £1000 up front. And you, TJ, being the one who criticises people borrowing to buy stuff.

NB £1000 being the price of a Rohloff, the only serious contender – Alfine either lacking range or being unreliable (by all accounts).

Trimix

Other alternatives are a solution to a problem that just does not exist in the real world….No one racing Enduro, XC or DH is asking for an alternative.

I’m sure they are perfectly reliable for the 2 hours or so of use they get before they go back to the workshop.

BTW I’m not trying to justify hubgears here, just querying whether there is a better design option for derailleurs. I recognise that they are lighter and more efficient than hubgears.

I’m sure they are perfectly reliable for the 2 hours or so of use they get before they go back to the workshop.

If you are taking your derailleurs back to the workshop every two hours then I respectfully suggest that you do not know how to set up and maintain derailleurs. Seriously, I do not have to do this. I set them up then I do not touch them, they continue to work.

No

Kerley – nope you can run an alfine or a rohloff on any bike. You just need a tensioner ( and a speedbone for the rohloff)

Molgrips – alfines are MUCH cheaper than derailleurs and for me even the rohloff is after 7 years usage. alfine 8s are totally reliable.

As scotroutes well knows, my opinion of mtb derailleurs is scathing.

It’s in the name. 😊

Anyone who has ever worked in a bike shop will tell you that you need to order derailleurs in bulk and spend all your workshop time replacing them.

Or maybe not…

molgrips

If you are taking your derailleurs back to the workshop every two hours then I respectfully suggest that you do not know how to set up and maintain derailleurs.

I know you like to misinterpret my posts, but to make it clearer, I was referring to Trimix’s mention of racing, what happens to bikes used by actual racers, not amateurs. It only has to last the race, so of course they’re not going to want anything changed.

I’ve probably been fixing derailleurs (properly) longer than you’ve been alive.

i have both alfine and rohloff and extensive use on both over the years – i did try and use the rohloff on my main bike.

regardless of(your percieved man math justification cost) i STILL prefer a derailleur and use the the rohloff in deep winter slop simply because its attached to my fat bike.

Hols – don’t forget the saving on chains, cassettes and chainrings.

Steel Deore stuff lasts for years. Gearbox bikes have chains and chainrings too. I don’t see how chains and chainrings are going to stop wearing out just because there’s a gearbox in the system.

The main reason I got the rohloff was reliability. MTB tandems break every hub known to mankind bar a couple of very expensive tandem specials or the rohloff. £600 for a special order chris king plus a derailleur, cassette, 2 chainrings or £1000 for a rohloff one sprocket and one chainring