Why are front mechs so rubbish?

weescott

The rear mech is nice and smooth to change gears, but the front seems to constantly be trying to snap your wrist from the amount you haave to push the lever.

Worst designed part of a bicycle?

supersonic

They tend to have stiffer springs than the rear mech, and different cable pull and leverage so can feel harder to push. If it is feeling really harsh though I'd make sure the cables are all nice and smooth, and the cage pivots arent siezing. The siezing has been a problem for me on the past.

ddraver

I'm with both of you - It's amazing no one has come up with something better for the front but keeping them cleaned an oiled makes the best of a poor job! It's probably something that harkens back to the roadie thing as they work much better on 2 rings (unless you re Andy Schleck...)

supersonic

I suppose we have Hammerschmidt which many are liking.

Anonymous

ddraver wrote:

It's amazing no one has come up with something better for the front

You're right. I wish someone would hurry up and invent Hammershmidt

Dirtydog11

weescott wrote:

The rear mech is nice and smooth to change gears, but the front seems to constantly be trying to snap your wrist from the amount you haave to push the lever.

Worst designed part of a bicycle?

+1

It would be nice if they could come up with something with a lot less throw at the lever end.

weescott

Hammerschmidt is a great idea but far too heavy for XC riders. That new 3 speed internal geared 10 speed hub looks promising though.

Anonymous

weescott wrote:

Hammerschmidt is a great idea but you far too heavy for XC riders. That new 3 speed internal geared 10 speed hub looks promising though.

No, XC riders are just poofs. They need to MTFU

Nicklouse built up a bike with a hammerschmidt recently, and gave the weights of it. It's not actually too bad.

supersonic

Less throw means a harder push though. I don't know why they need to make the spring so violent though!

weescott

Would it not be possible to have a bigger leverage ratio built into the shifter?

/goes looking for an old shifter to pull apart.

supersonic

Yep, but would make for a longer throw. I think more upmarket shifters use better internals for less friction and optimum ratios that suit the majority of people. It seems they purposely make lower end stuff harder to push, or feel very sloppy!

ddraver

yeehaamcgee wrote:

ddraver wrote:

It's amazing no one has come up with something better for the front

You're right. I wish someone would hurry up and invent Hammershmidt

I said Better - not different!!!

delta5

weescott wrote:

. . . the front seems to constantly be trying to snap your wrist from the amount you haave to push the lever.

Yep, hated that too.
One option is to change to a gripshift. I use SRAM X0 gripshifters front and back, and the front works almost effortlessly. Also lets you move the front mech in small indexed increments, so you can avoid the chain rubbing on the front mech when you're using the extremes of the cassette - just tweak it one click up or down, and no more annoying scraping noises . . .

Anonymous

Delta5 wrote:

Also lets you move the front mech in small indexed increments,

Wow, ever since we've had indexed gears, I've DREAMT of a way to go back in time, and SRAM has been providing the answer, unbeknown to me!

ROCHA

supersonic wrote:

Less throw means a harder push though. I don't know why they need to make the spring so violent though!

If the spring wasn't as strong then you couldn't move the chain to a smaller ring.
Moving the chain up and down on the sprockets is much easier 'cause the mech pushes sideways on the half of the chain which is not being pulled by the crankset. You could move the chain to the correct sprocket just by pushing it with your finger even if you're pedalling hard ...if you could do that while pedalling and you weren't too affraid to get your finger snapped That's why it's smoother to operate. Tension on the lower half of the chain shouldn't be more than a couple of Kg.

On the upper half of the chain thing's are quite different..
If you have all your weight(say 70kg) on your front pedal while yor crank(175mm) is horizontal you can put a very big tension on the chain(about 4 times your bodyweight).

Calculations:
Radius of a 22t chainring= 22 * 12.7mm(half an inch)/2*pi=44.5mm

70Kg * 175mm=XKg * 44.5mm :arrow: X=275Kg :shock:

So, to push sideways a chain this stretched is hard... It's not the front mech's fault. It really neds a strong spring to move the chain to the inner ring, just as you have to push hard on the shifter to push the chain to the outer ring. Some plastic shifters flex noticeably. Luckily for us, we all have big strong thumbs because of playing videogames for hours :twisted:
There's a reason why there are no reverse action front mechs.

singlespeed :?: :idea:

Anonymous

I understand what you mean with the tension on the chain, BUT, that is some ropey science/maths right there

You still don't need too much force to shift it to another chainring, in fact, the chainrings are designed to assist the chain in jumping over.

Buckled_Rims

The road bikes already have a solution, it's called Shimano DuraAce Di2. Electronic changing front and rear gears. Never tried one, but everyone loves it by the sounds of it.



....Oh, and it's expensive :!:

ilovedirt

yeehaamcgee wrote:

ddraver wrote:

It's amazing no one has come up with something better for the front

You're right. I wish someone would hurry up and invent Hammershmidt

I thought he said something better?

Anonymous

ilovedirt wrote:

yeehaamcgee wrote:

ddraver wrote:

It's amazing no one has come up with something better for the front

You're right. I wish someone would hurry up and invent Hammershmidt

I thought he said something better?

He did, I replied Hammershmidt.
Oh do keep up

ilovedirt

yeehaamcgee wrote:

ilovedirt wrote:

yeehaamcgee wrote:

ddraver wrote:

It's amazing no one has come up with something better for the front

You're right. I wish someone would hurry up and invent Hammershmidt

I thought he said something better?

He did, I replied Hammershmidt.
Oh do keep up

:roll:

Anonymous

Sorry but I can't see the problem.

I have nothing fancy on my bike - SLX shifters and a XT front mech with a cheapy FAS chainset.

Not once have I ever been concerned by the amount of effort it takes to change the front rings.

Anonymous

go on then, ilovedirt. Please enlighten us as to why you don't like the hammerschmidt concept.

nickfrog

1x9 or 1x10. Job done.

ilovedirt

yeehaamcgee wrote:

go on then, ilovedirt. Please enlighten us as to why you don't like the hammerschmidt concept.

For what it is, it's ridiculously expensive, and from the sounds of it, it needs refining a little before it's a viable replacement for a dual and bash... I'm happy to stick with a single ring.

salsarider79

My front mech was a nightmare, til I figured that when I built the bike I added far to much cable. Cue a tiny bit of fettling and hey presto, front shifts with no real pressure now.

XTR shifters work really well BTW

Northwind

I too have never suffered the misery of stiff front mech shifts Are y'all cripples or something? Now, setting the ****ers up, I hate, but shifting with them is fine.

I guess electric shift is probably going to be the solution some of you are looking for...

cooldad

I'm thinking of getting someone else to ride my bike. Save some pain and suffering, and getting cold and wet. And then I don't have to worry about set up at all.

bike-a-swan

Northwind wrote:

I too have never suffered the misery of stiff front mech shifts {/quote]
ditto

rudedog

never had a problem shifting the front mech either - never even thought about it until now.

ilovedirt

When i ran a Saint front shifter with an LX front mech, oh my god that was a bugger to shift, and index. That was the final straw for me, I haven't had a geared front chainring since.

Paul 8v

I don't think It's a problem to be honest, never thought about it before