Claris with Altus?

[fastpedaller]

I'm getting used to my Spa Tourer, and really enjoying it - I've changed to straight bars, and have Shimano Altus Brake/gear changers (the EEZi Fire action). They seemed to work pretty well up until last week, but the front changer (A Claris triple) seems to now be not quite as expected......... I unshipped the chain whilst changing from middle to outer ring today I don't often venture into the outer ring, but when I do it's a pain if it overshoots the chain onto the crank!. Then a couple of times, when I changed (or tried to change) from outer to middle ring, it didn't move to the middle ring.
I've not fiddled with it yet, but I wonder if there's a problem with the cable pull ratio? I recall someone saying that road and MTB components have different pull ratios - Is that so? I can only use a bottom pull front mech with his frame, but using the straight bars restricts the changers I can use. The first thing I'll address is whether I can drop the mech a mm or 2 to try and stop the chain overiding the big chainring. I could also put the cable the other side of the pinch bolt to alter the pull ratio...... Any advice gratefully received.

[cycleruk]

Yes MTB and road front derailleurs have different cable pulls.
Road = 12mm per click.
MTB = 19mm per click.
So the Altus will over-shift the Claris by 4mm over the 3 rings.
Not sure where the cable is clamped but moving it further to the end of the arm will reduce the throw.
Other option, but costly, there are Claris flat bar shifters which would obviously match.
It is also possible that an MTB front mech' could be made to work depending on the chainset ring sizes.

[fastpedaller]

Yes MTB and road front derailleurs have different cable pulls.
Road = 12mm per click.
MTB = 19mm per click.
So the Altus will over-shift the Claris by 4mm over the 3 rings.
Not sure where the cable is clamped but moving it further to the end of the arm will reduce the throw.
Other option, but costly, there are Claris flat bar shifters which would obviously match.
It is also possible that an MTB front mech' could be made to work depending on the chainset ring sizes.

Thanks for your help.
Do you mean 12mm and 14mm to overshift 4mm, or 12mm and 19mm giving 14mm?
Clearly there's a difference that I wasn't aware or before I purchased. I have an Altus rear mech, so would using Claris flat bar shifters give a similar problem (but on the rear) or is the pull for the rear mech the same for both MTB or Road?
Another question....... Why are road and MTB front changers different anyway?

[gbnz]

I'm not experiencing any issues with flat bar / road shifters (The 8spd shifters which preceded the Claris type) and the Altus rear deraileur I fitted to my new Spa Tourer frame a couple of weeks back. Nor had I have had any issues with the XT rear derailuer and the flat bar/road shifters in the 3 years prior to the Altus rear derailleur being fitted.

Should be ok

[Brucey]

the rear shifting will be no problem but the front shifting has an incompatible cable pull

cheers

[Brian73]

Your brake levers may not be compatible too if you haven't swapped the cantis for V brakes.

[Freddie]

Does anyone else envision pottery whenever Claris is mentioned?

[fastpedaller]

Ok it's fixed - thanks for the help gents. I didn't know Shimano had different cable ratios for MTB or Road for front mech - Very strange, almost as if designed by different departments!
Anyway, rather handily, the protrusion at the clamp bolt, which guides and 'supports' the cable proved useful to support the stainless steel extension I fabricated....... A slot to take the cable, and a groove filed on it's front face to clamp the cable against the lever arm (if that makes sense), thus extending the lever length between cable and pivot point by about 7mm.
All seems to work well now - time will tell

[cycleruk]

Yes MTB and road front derailleurs have different cable pulls.
Road = 12mm per click.
MTB = 19mm per click.
So the Altus will over-shift the Claris by 4mm over the 3 rings.
Not sure where the cable is clamped but moving it further to the end of the arm will reduce the throw.
Other option, but costly, there are Claris flat bar shifters which would obviously match.
It is also possible that an MTB front mech' could be made to work depending on the chainset ring sizes.

Thanks for your help.
Do you mean 12mm and 14mm to overshift 4mm, or 12mm and 19mm giving 14mm?
Clearly there's a difference that I wasn't aware or before I purchased. I have an Altus rear mech, so would using Claris flat bar shifters give a similar problem (but on the rear) or is the pull for the rear mech the same for both MTB or Road?
Another question....... Why are road and MTB front changers different anyway?

Sorry - somehow missed the 1 off 14.
But happy that you have a solution for the problem.
Nice fix but possible cable failure due to the sharp edge of the slot.

Another bit of info'-
Both MTB and road rear dérailleurs have the same cable pull until you get to 10 speed MTB.
So Claris rear shifter will operate an MTB derailleur perfectly.

[fastpedaller]

But happy that you have a solution for the problem.
Nice fix but possible cable failure due to the sharp edge of the slot.

It's not possible to see from the photo (cable in the way ), but the slot has been smoothed to a nice radius using the rifler file I fortunately found after a very quick search! The old memory bank works sometimes. Thanks again for your help. If the cable breaks at least I'll be able to get home with a lot of twiddling!

[Brucey]

Nice work!

I think that the cable may eventually fatigue but I don't think what you have done is appreciably worse than how some mechs are from day one.

As per a comment I have made in another thread, I think this adaptation will also allow some campag ergos to work better with shimano 'road' front mechs, by reducing the cable tension required to keep the mech in the right position.

cheers

[fastpedaller]

Thanks for your kind words Brucey. I decided yesterday eve to see if I could improve it further, so here's the result....... A little longer, but I really couldn't get it any shorter due to the 'twist' . I created it (again using 2mm stainless) using an old pg spoke as a press tool, tapping the spoke with a small hammer, and then a twist in the vice - all rather primitive metal bashing, but I think it's an improvement, and it works in the stand. Time will tell, but I'll keep version 1 in case the ratio is better .