Stiff front changer

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fausto copy
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Joined: 14 Dec 2008, 6:51pm
Location: Pembrokeshire

Stiff front changer

Postby fausto copy » 24 May 2018, 8:45pm

We recently had my wife's touring bike converted to flat bars, as she could no longer manage the bar end changers on her drops.

However, having had new combined Shimano (Revo?) shifters, she is no better off, as she cannot operate the front changer.
I've experimented with several things including changing the front mech from a Shimano 105 to a Suntour Pro, and have changed chainrings to 24-36-42.

An experienced friend had a look at the set-up and couldn't believe how stiff the lever appeared (although I can change gears on it OK) and has advised changing the new levers to Shimano XT or XTR as he says they provide a much slicker change (mind you, he's got arms like Garth anyway).

I called into the LBS who fitted them and mentioned it today and they merely said it could be worth changing to a twist grip lever and have offered to take the bike back in next week.

However, I'm wondering if the problem is the spring strength of the Suntour mech and would a switch to an XT or XTR mech be worthwhile.
(I foolishly sold half a dozen such mechson here recently and have none left to experiment with :roll: )

Any ideas please?

Cheers, fausto.

Brucey
Posts: 29892
Joined: 4 Jan 2012, 6:25pm

Re: Stiff front changer

Postby Brucey » 24 May 2018, 9:24pm

if it is a 'road' FD and an 'MTB' type shifter then the cable pulls will mean that the force required to make an upshift may be up to x2 more than it should be. And come to think of it, the indexing will not work properly on a triple either so I suppose that you have an MTB mech.

Really you need to show what the setup looks like, specifically vs chainline , cable access angle at FD, cable routing and so forth.

BTW the FDs that have the lowest force are often the ones where it looks like the cable is wrapped around a pulley rather than attached to an arm.

I am very doubtful that a gripshift type shifter will improve matters unless it is internally geared in some way (some shimano units are, I think) and XTR is meant for pro racers; if anything the shifts are heavier and clunkier (vs XT) in the incarnations of XTR that I have tried.

TBH bar end shifters set to work an MTB FD require a pretty modest force; if anything this is likely to be a lower force than many other combinations of shifters and mechs. Something very simple, like extending the lever on a bar end (or, thumbie or bar end converted to thumbie) might work for you?

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

gxaustin
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Joined: 23 Sep 2015, 12:07pm

Re: Stiff front changer

Postby gxaustin » 24 May 2018, 9:26pm

I changed from flat bars to drops because the left hand changer was killing my thumb. I used the non series road mech changer since I had all road mechs

Steve O'C
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Joined: 3 Mar 2013, 1:32pm

Re: Stiff front changer

Postby Steve O'C » 24 May 2018, 9:47pm

I managed to route the cable to my front derailleur the wrong side of the little tab next to the pinch bolt :oops: . Made it very difficult to change gear. It should go like this (but I expect you knew that already).

Steve

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gaz
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Re: Stiff front changer

Postby gaz » 24 May 2018, 11:09pm

Brucey wrote:if it is a 'road' FD and an 'MTB' type shifter then the cable pulls will mean that the force required to make an upshift may be up to x2 more than it should be. And come to think of it, the indexing will not work properly on a triple either so I suppose that you have an MTB mech.

BITD I managed to index a Suntour Superbe Pro front mech from RSX triple shifters. Indexing was near as damn it but the cable had to be routed the wrong side of the clamp bolt to achieve it.

Having effectively shortened the lever there was excessive resistance to moving the shifter. I gave up on it very quickly and reverted to bar end friction shifters.

Brucey
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Joined: 4 Jan 2012, 6:25pm

Re: Stiff front changer

Postby Brucey » 25 May 2018, 2:31pm

FWIW spring loading in FDs varies enormously; some (eg old campag road) pull back on the cable with a force of 15-20lbs and others pull back about half that amount. Maybe we should start to collect information on this point.

One of the things that makes a difference is the geometry of the mech and the chainline it is run at. Some MTB mechs will allow you to run a 'road' chainline but the arm is nearly vertical when you are on the small chainring, which makes for a really hard pull on the cable when time comes to upshift.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

peetee
Posts: 521
Joined: 4 May 2010, 10:20pm

Re: Stiff front changer

Postby peetee » 25 May 2018, 5:38pm

+1.
I had a bike in that had been fitted with a bottom bracket that was too short so with the chain on the smallest ring the cable pull was near on through the pivot line.
Current status report:
Latter side of fifty and feeling less than nifty.
Too many bikes on pegs and too few miles in the legs.

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fausto copy
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Joined: 14 Dec 2008, 6:51pm
Location: Pembrokeshire

Re: Stiff front changer

Postby fausto copy » 31 May 2018, 8:57pm

And now for the good news.......
thanks to colin54 offering to let me have back the XT derailleur I recently sold him,
Mrs. C can now change gear. :lol:
I removed the Suntour, fitted the XT and immediately noticed a difference.
A bit of fettling got it changing smoothly and my test ride seemed to confirm it.

Mrs.C went for a test ride (which lasted a bit longer than I expected and had me worrying)
but she came back beaming.
Small ring to middle a doddle and she can now even change up to big ring with a bit of effort.

So, a happy ending and a big thank you to Colin,
(and to all who replied to my query)
fausto.