Front mechs

[Radar]

After spending what seemed like many hours* attempting to install a new front mech to the Pace I gave up in disgust, took it to the shed and came back inside to make a casserole.

Yet my road bikes, new mech installation is a 5 minute job as they are braze on front mechs. Much simpler, much easier and quicker. Surely a lot less hassle for suppliers - mechs are made to one standard, with a range of clamp bands available/ or mounts are ready built into the frame.
Got me wondering. Apart from a few examples a gazillion years ago, why did the braze on front mech never really catch on in the offroad world?




* which was probably about 30 of your earth minutes. Middleburn cranks, spider and rings, with 95x XTR front mech. Really bloomin awkward, kept getting the inner plate catching on the middle ring. Obviously not holding my mouth right. Will sacrifice something to the gods of fettling, and try another day when I have my spanner mojo back

 

[legrandefromage]

Unfortunately front mechs are quite tricky to set up on anything other than thumbies.

You have different cable pulls from the various models of off-road STI

Then there is the reach of the mech itself

And the swing of the mech

And then theres the chainrings, some mechs 'only' fit 44t or 46t or 48t outers etc etc

Same for the road world, you cant just throw on any mech with any STI

And all that is just Shimano...

 

[FluffyChicken]

Re:

Top (new style m950) or bottom swing (traditional retro styling) front mech.

My pave fitted quickly and easily.

If it's hitting the chainring then it's too low.

Work at 5mm or a bit more clearance from the top ring and set it up. Then once it's working, lower it to the 2-3mm clearance if it can. Then just release a bit of cable on the adjusters.


I guess the main thing you may notice is you need to align with the clamp near tight and then notice how much out of adjustment it needs as doing up the band clamp moves the alignment. Stems and other part can do that similar trick to your frustration.

 

[hamster]

Indexing front mechs is such a daft idea. It's not exactly as though you cannot feel as it engages with a big shift in cadence.
Thumbies were much the best way, plus you had the advantage of easy trimming.

 

[The History Man]

+1 for above. My rat explosif has a front thumbie and rear indexed xt thingie. Try it. The trimming is so much more versatile.

 

[FluffyChicken]

Re:

Why is it always a debate to go thumbies, I for one don't like them.

He just wants help setting up his stuff with what he has.

Early pace used a braze in but they bend and snap off.

Modern bikes of certain setup use a braze on idea of fitting.
It does limit you to the style if mech you can use and the degrees of adjustment. Though they just make them in every style now to solve that.
http://www.ridextr.com/en/productcatego ... nt,FD.html

 

[Radar]

Re:

I can normally 'do' front mechs. But I do believe they are partly operated by witchcraft. If I don't get it more or less right first time then I tend to think a bit too hard and it goes from bad to worse. At that point I put everything away for another day. I know exactly what went wrong I paid attention to the guide sticker on the outer plate, being pestered by radarlings at the same time didn't help.

I was more interested in why braze ons never really took off in the offroad world. My going to work roadbike has a bolt on band to accept a braze on mech. Great. That would be fab for off road and all the ocd types on here (myself included) who like to clean their bikes properly. My road bikes get stripped annually (usually when the roads are free from gritting wagons), new cables and bar tape. Mechs get deep cleaned and relubed. Absolute doddle with a braze on mech. Having just deep cleaned my Pace I have replaced the front mech. Cue faffing ahoy!

 

[hamster]

I think the main reason for no braze-ons was cost. A wider variety of chainring sizes probably didn't help.

 

[FluffyChicken]

Re:

Hamster, they bent and would need a frame builder to repair properly if it dented the frame. Clamps where much easier to just swap the mech out. Of course a combination could have been used but that was more parts I guess.


MTB had bouncy loose chainslapping, chainsucking setups with twigs, nettles plants rocks etc all ready to yank the front mech

 

[mattr]

Probably explains the rise of the replaceable gear hanger as well. Not many would stand for a minor off writing off the frame, or at least require the attentions of a frame builder