Are all front mechs created equal?

[Polar Bear]

I like tech but I'm not an early adopter.  Di2 seems like a dream for people with arthritic or other issues affecting hand strength.  Clearly it was not really designed for that but hey, why look a gift horse.  I'd like to give it a try sometime.  Is it available for flat bars?

As for car electrics being unreliable, I have to disagree.  There are millions of the darned things cluttering up the roads but very few fail in everyday use.  In fact, the mechanical reliability of cars since I worked in a garage in the eighties has massively improved and I believe that electronics plays a big part in this.  Given that a fully loaded car might have 100kgs of electronics in 1500kgs of slab it's not added too much weight, possibly even replaced lots of heavy mechanical bits.   Reliability of cars tends to be a function of owner neglect as people treat a car like a phone, television or cooker - they just expect it to work regardless.

Cars are more economical than they were 30 years ago, need servicing less and are generally safer (driver aids, collision avoidance, lane keep, airbags, belt tensioning, etc) and quieter places for the occupants to be.  And, electric cars are much more reliable than ICE ones.   

[Kim]

Is it available for flat bars?

The hub gear flavours certainly are.  You'd hope that the various shifter buttons would be interchangeable, but in the best tradition of bicycle components, I wouldn't be surprised if they aren't.

[Jakob W]

XTR comes in a Di2 flavour with flat-bar shifters; no idea whether these will work with road components.

[telstarbox]

My front derailleur is the oldest bit of the drivetrain still on my bike with about 7000km of service. It is a Shimano TZ31 which appears to be as cheap as the rest of the bike (Decathlon). Is it likely to have much more life and is it likely to fail 'explosively' or just become less effective at some point? 

[Brucey]

.... but very few fail in everyday use.  In fact, the mechanical reliability of cars since I worked in a garage in the eighties has massively improved and I believe that electronics plays a big part in this.

there are just as many mechanical bits as in an older car and believe it or not they have been improving those too, without which the car would still break.
If they have made improvements in the reliability of electronics they have failed to keep pace with the increase in the amount of electronics in a car. The net effect is that it is very likely that you car will suffer numerous electronic faults in its lifetime.
 

Given that a fully loaded car might have 100kgs of electronics in 1500kgs of slab it's not added too much weight, possibly even replaced lots of heavy mechanical bits.

 

If only!  There is at least 250kg of electric nick-nacks in any modern car that has any pretensions of being 'loaded'.  BMWs have an online ETK that has component parts listed along with weights and you can add them up.  They almost invariably add weight; for example have you tried lifting an electrically adjustable seat? It is barely possible; they have to use a crane in the factories to install them. The same goes for modern dashboards.

Engines, gearboxes, trim parts, most suspension parts and non-stressed bodywork has all got lighter. The stressed parts of bodywork have stayed about the same weight or slightly increased (but they have got stiffer and stronger) and the weight of electronics has increased. The net effect of all this is that modern cars are much, much heavier than older ones. The main increase in weight has of course come from electrical parts.

 cheers

[Polar Bear]

I make a distinction between electronics and electrics.   Things like electric mirrors, seats, windows, central locking, etc. have been in cars for a long time and are essentially electric with a small amount of electronics.   Complex electronic such as for ever more complex engine management, fuel and exhaust management, suspension management, LED displays replacing instrument and in car entertainment  clusters etc. probably weigh less than the stuff they replace.  the mechanical devices to do the work demanded by these systems probably adds weight and definitely adds complexity.     

Manufacturers have turned to the gadgets and gizmos for entertainment because  the fundamental mechanicals are pretty well refined.   For instance, no longer do car companies offer a larger engine for more power, they simply map one engine a number of different ways.  Instead they are obsessed with lcd displays, the ability to 'fiddle' with a billion car settings and internet connectivity.

[Polar Bear]

Anyway, sorry to go off topic. 

[ElyDave]

I've never had an electronic failure in a car, but my newest CA, the current one is a 2003 landrover, probably not a lot of electronics in thàt. My previous car had a cracked exhaust manifold for years, the engine e management carried on OK and it eventually failed mot on emissions being too low.

I've never had a cable break on a bike either

Pat's table quickly

[fasilbalti]

I've skipped all the electronics stuff so may have missed something but...

...has anyone mentioned seat post/chain stay angle?

I replaced the XT mech on my old hardtail a few years back and it was a factor.

[Brucey]

it can be a factor but on an older bike it used to be easy unless you wanted to run an MTB indexed front shifter/chainline on a bike with large wheels or a 'road' chainline/indexed front shifter on a bike with 26" wheels.  In both those circumstances the stay/seat angle of most mechs would be wrong.

Just to confuse you there were a few oddball shimano mechs;

Some FD-R4** mechs run 'road' chainlines on frames with large wheels and use MTB style flat bar shifters

Some XT components are meant to form part of 'trekking groupsets' so are correct for running MTB chainlines on large-wheeled frames with flat bar shifters.

Since 29er style MTBs have become popular stay/seat angles have changed somewhat but there is still a lack of FDs that run road triples from indexed (road) style shifters.

In road doubles the latest FD designs from shimano have an extra linkage that separates a cable pulley from the parallelogram linkage, and there is an extra screw to adjust the coupling between the two. This gets away from the issues of the cable tension and mech shift ratio varying on different frames, with small changes in alignment of the front mech, caused by different width seat tubes.

cheers

[LittleWheelsandBig]

My front derailleur is the oldest bit of the drivetrain still on my bike with about 7000km of service. It is a Shimano TZ31 which appears to be as cheap as the rest of the bike (Decathlon). Is it likely to have much more life and is it likely to fail 'explosively' or just become less effective at some point?

The latter. Of course, a progressive decline in performance eventually reaches the point where 'it just stops working'.

[Brucey]

I make a distinction between electronics and electrics.   Things like electric mirrors, seats, windows, central locking, etc. have been in cars for a long time and are essentially electric with a small amount of electronics.....   

well split hairs if you like but (and this was the whole point of this sidetrack I think) that is quite like a Di2 system, isn't it?  The results are similar too; for a small improvement in utility at best, the system is needlessly complicated, heavier and in practice noticeably less reliable with multiple points of potential failure.

I have personally experienced multiple failures of exactly this type of system in many different cars, outnumbering genuine mechanical faults handsomely.

As I mentioned earlier this constitutes the very antithesis of what I like about bicycles and cycling.

cheers

[ElyDave]

My front derailleur is the oldest bit of the drivetrain still on my bike with about 7000km of service. It is a Shimano TZ31 which appears to be as cheap as the rest of the bike (Decathlon). Is it likely to have much more life and is it likely to fail 'explosively' or just become less effective at some point?

The latter. Of course, a progressive decline in performance eventually reaches the point where 'it just stops working'.

mine just stopped, no noticeable decline

[Brucey]

perhaps it was a seized pivot or a broken spring?

cheers

[ElyDave]

yes, that's where we started.  I tried to free the pivot but no luck, another one is on order

[LittleWheelsandBig]

My front derailleur is the oldest bit of the drivetrain still on my bike with about 7000km of service. It is a Shimano TZ31 which appears to be as cheap as the rest of the bike (Decathlon). Is it likely to have much more life and is it likely to fail 'explosively' or just become less effective at some point?

The latter. Of course, a progressive decline in performance eventually reaches the point where 'it just stops working'.

mine just stopped, no noticeable decline

Your front mech wasn't an all-steel TZ31 and 'likely' does not equal 'in every instance'.