Will this set up work?

[cavasta]

Looking to upgrade a touring bike from bar end shifters to STIs. Using Tiagra shifters, will a Tiagra FD 4503 front mech be ok with a 48-38-26 chainset (with a 9 spd 11-32 cassette)?
Or will I need to run a 48-38-28 chainset with an 11-34 cassette?
The Shimano technical docs state that the 4503 can handle a 20 tooth maximum capacity. Are they just been over-cautious or is this written in stone? Is there any room for manoeuvre?
I've heard of, though not met or spoken to, people using a 4503 with a 48-38-26 chainset. What I don't know is whether or not any "modifications" were required to get it to work, or if the shifting has been affected in any way.

[meic]

You can do either option.

I even think that Dawes did exactly that on one of their latest Galaxy models.

There is plenty of room for manoeuvre with the inner ring.
As CJ pointed out just a few days the most important figure is that you should have 11 tooth difference between middle and outer rings.
However there is no great disaster waiting if you take that to 10 or 12 teeth difference.
I think that your first choice is the better option but as you will have to buy the 26tooth ring as an added extra then I used the second method to make use of the 28 tooth inner ring that I already have.
So I have 50, 39 28 on my front using the same Tiagra dérailleur with the 32 tooth rear cassette.

If you havent already bought a cassette then jump in here quick. If you have then stock up a spare already.

http://www.chainreactioncycles.com/Mode ... delID=5213

[cavasta]

Thanks meic. The 48-38-26 with an 11-32 is my preferred choice as well. Looking on Spa's website they do a custom TA chainset, where you can select your preferred set up, rather than have to go with an off-the-peg set:

http://www.spacycles.co.uk/products.php ... 0s109p2004

Thanks also for the heads up on the cassette. That's a bargain in anyone's book. I've ordered the 11-32.

[meic]

I find it odd that they suggest a JP400 Bottom Bracket to go with such an exquisite/expensive chainset.
I would spend less on the chainset and buy the fantastic TA Axix light bottom bracket with the money saved. Failing that get a Shimano UN54, I bought a JP400 and put it straight into a drawer after I had held it in the flesh so to speak, such a heavy lump of a bottom bracket.

[fatboy]

Your set-up will work. I've got STI shifters with a Sora front mech and I run 22-38-48 with 11-32 at the back. The gear change is a bit slow at the back when in the 22-cog but it works just fine despite being miles outside the spec. I've heard that the middle to big ring difference is the important one to maintain.

[Wesh-Laurence]

The Tiagra STIs will work fine with the rear derailleur/cassette as long as you are using a long caged derailleur.

Others on this forum have said that the front derailleur/chainset combination you have quoted should work as well. However I couldn't get the front (road) Tiagra 4503 derailleur to work with a 26/36/48T chainset and therefore I fitted a M591 (MTB) front derailleur mech and a "Shiftmate" to increase the cable pull of the STI levers.

Basically the Tiagra STI levers work with a rear MTB derailleur. However the Tiagra STI levers don't pull enough cable to work with the front MTB derailleur mech.

[cavasta]

Thanks to all who contributed. I've bitten the bullet and gone for Tiagra shifters and front mech (4503), 48-38-26 chainset and 11-32 cassette. Awaiting delivery of said components with bated breath...

[fatboy]

Just a note the front mech will be fiddly to fit and set-up but will work once you've patiently set it up!

[cavasta]

Just a note the front mech will be fiddly to fit and set-up...

From which point of view: because the 22 teeth difference between inner and outer is beyond Shimano's stated maximum capacity or because there's a 10 tooth difference, rather than 11, between the middle and outer?

[fatboy]

Just a note the front mech will be fiddly to fit and set-up...

From which point of view: because the 22 teeth difference between inner and outer is beyond Shimano's stated maximum capacity or because there's a 10 tooth difference, rather than 11, between the middle and outer?

The inner and outer won't be a problem. The issue is that the front mechs are really designed for bigger chainrings, road bike chainlines etc. I found the whole thing a complete faff especially as my shifters don't have a trim function (tiagra do I think!). A friend of mine gave up getting his going and went to his LBS who got it working but moaned that it had taken a lot of faffing.

[cavasta]

The inner and outer won't be a problem. The issue is that the front mechs are really designed for bigger chainrings, road bike chainlines etc. I found the whole thing a complete faff especially as my shifters don't have a trim function (tiagra do I think!). A friend of mine gave up getting his going and went to his LBS who got it working but moaned that it had taken a lot of faffing.

I guess that's my bank holiday weekend taken care of then.

[stewartpratt]

May I be cheeky and ask what you're doing with your bar end shifters?

[cavasta]

May I be cheeky and ask what you're doing with your bar end shifters?

I think I can see where this one's heading I'm going to hang on to them. I'm a bit of a hoarder when it comes to bike parts; they'll go with the rest of my collection. They may never see the light of day again. On the other hand...

[stewartpratt]

Understood. That's exactly what I'd be doing, and that's exactly why my garage is so hard to move around in

[JEJV]

The inner and outer won't be a problem. The issue is that the front mechs are really designed for bigger chainrings, road bike chainlines etc. I found the whole thing a complete faff especially as my shifters don't have a trim function (tiagra do I think!). A friend of mine gave up getting his going and went to his LBS who got it working but moaned that it had taken a lot of faffing.

I guess that's my bank holiday weekend taken care of then.

We have 4503 working fine with 46-34-24 - I think (somone please contradict me if this is rubbish) that the 4503 is designed for for Compact triples - like 50-39-30, so a 48 big ring should be fine.

I'd have gone for 48-36-26, because that makes the jumps a little more even.