Now it's the front derailleur

[iansoady]

Flushed with success after getting the rear brake cable installed and working well, I now turn my attention to the gears on my wife's Raleigh Pioneer. It has a Suntour front triple chainset (42/34/24) and a Shimano FD-TY30 front derailleur with a simple indexed thumb shifter. I suspect at least one of these were not present when it left the factory. And I know that none of this is high-end stuff.

The problem is that although I can get it to change well between the middle ring and the small one (after perusing many posts here), it will not move the chain onto the big ring. I believe I have tracked down the problem to the fact that the chainline (to the inside edge of the middle ring) is 50mm. I've managed to find a data sheet for the derailleur which states that it is intended for use with a 45mm chain line. So my conclusion is that the derailleur is unable to move far enough across to move the chain to the big ring. I have backed off the H limit screw completely and have tried preloading the operating cable. This merely makes the thumb shifter "bounce" back out of position 3, and still doesn't achieve the high gear. I do accept that we may have an incompatible mix of bits here, but as I say the 1-2 and 2-1 changes are smooth and accurate.

A little bit of research tells me that the Shimano FD-M590 derailleur specifies a 50mm chainline. These are readily available for a few pounds on ebay. My plan is to get one of these and try it - what do I have to lose?

In fact, my wife would probably be quite happy with just the two smaller rings as she isn't one to explore the upper end of the speed range, and the bike will probably often be seen with a cute willow basket up front. But I hate having things that don't work properly. I know the "proper" answer is possibly to change the BB but to be honest I'm looking for an economical solution here.

I welcome all constructive suggestions....

[Brucey]

50mm chainline is standard for a MTB chainset, and may or may not be as good as you can achieve using that chainset on that bike. A new FD would seem to be the thing, but note that your 'indexed thumbshifter' may not have the correct pull for it, which will mean another shifter is required.

I would suggest that you take a look at the bottom bracket/chainset, review the actual FD travel and see if a shorter BB will sort you out. If it will, then it will likely be simpler than a new FD and a new shifter.

cheers

[fausto99]

The Shimano FD-M590 derailleur looks like the cable pulls the other way compared to what you have currently. Even if it's compatible with the current shifter, this may involve you in a lot of cable re-routing, fixing and setting up.

Why not do the "right thing" ? Shimano sealed BB units are not hugely expensive and easy to fit. All you have to do is find one about 5mm shorter than your current BB and the job's done.

[fausto99]

50mm chainline is standard for a MTB chainset, and may or may not be as good as you can achieve using that chainset on that bike

Good point. You'll need to see how much clearance there is between the inside rotating bits of the chainset and the frame. If you lose 5mm, will something hit the frame?

[Brucey]

re FD; a bottom pull, bottom swing FD would be best, and something from the early 1990s would manage either a 'road' or a 'MTB' chainline, but mayn't be 100% satisfactory with an (unspecfied) indexed shifter. A lot of more recent MTB FDs are top pull, top swing, and won't work a 'road' chainline at all. However some of them are so-called 'dual pull' which means they can be used bottom pull if required, eg FD-M510



cheers

[iansoady]

Thanks all for the thoughts.

The BB is, I believe, an old fashioned cup and cone type although I haven't dismantled it as it runs sweetly and I've been leaving well alone. I will measure up to see whether there is clearance for the chainrings to move inward by 5mm or so. I'm not sure whether the threads (mid-90s Raleigh) would be compatible with a current BB set?

The FD-M590 is said to be capable of being used for both bottom and top pull, and the instruction sheet I have downloaded shows both methods so I think that aspect is OK. I take the point about the indexing on the shifter maybe being incompatible with the chainring spacing, but at worst I will just have to revert to the existing one.

If nothing else, I'm enjoying the learning experience!

[peetee]

Have you checked that the inner cage plate isn't contacting the middle ring and preventing the shift to the large chainring?
The Pioneer was originally fitted with a 28-38-48 crankset and a front mech with a more shallow inner cage plate.

[iansoady]

I ended up with a new FD-M291for the princely sum of £8.99 delivered. It took me about 30 minutes to install and adjust (I was a bit disappointed I had to split the chain as I could remove / replace the old deraileur by removing the little roller at the back) but otherwise no problems. It was easier than I thought it would be to get clean changes all the way up and down, although this is with the bike hanging from the garage roof - I'm sure it will need some tweaking when it's on the road.

Thanks for all comments.

I found the Shimano site https://si.shimano.com/#/ very useful for downloading manuals and specification sheets.