52/38/28 Tiagra Triple - Advice Please

[the snail]

What strikes me is how high the derailleur is - usually it's set to clear the big ring by 2 or 3mm. The middle of the cage is shaped, so if it doesn't line up with the middle ring, it won't shift well. The setup is out of spec, but I reckon it should just about work - I have a 5703 front derailleur with 50/39/26 rings which works ok, pays to be careful with gear changes though. The capacity is really pushing it . I think I'd run the chain a bit longer, and try to avoid small/small gears, maybe drop to a 50t ring or a smaller cassette if you can't get it to shift well. I run mine with a 28t cassette.

 

[si_c]

I think the recommendation to swap to 48/38/28 is the best bet along with 11-32 cassette should bring everything well within spec, although you might be able to get away with 11-34. I've had no problems spinning up to 25 mph on the flat with a 48-12 gear so I'd imagine you'll be fine with that top end and the low is pretty low.

 

[Ajax Bay]

I've had no problems spinning up to 25 mph on the flat with a 48-12 gear so I'd imagine you'll be fine with that top end

Si - I sort of agree with you, thobut. The OP's bike is a tandem and a 108" gear is really not enough on even the gentlest downhill. A key element in tandem Type 1 fun is barrelling downhill, ideally past singles. A 108" will get you 28mph at 100 cadence: I'd want more. The 11t will allow 30mph (with a 48t ring). Tradeoffs. Tradeoffs.

 

[Paul Walters]

OK everyone, here's the denouement to this.... I had a long chat with the seller yesterday after sending them an email with pics etc. In brief:
1. They acknowledge the set screws were not correctly positioned when the bike left them.
2. They're confident the chainstay damage is nothing to worry about, and in any case, any further deterioration in time will be dealt with under their warranty.
3. They know the gearing set up is out of spec, but it's a configuration they have fitted many many times, and works reasonably well, given the wider range of gearing often necessary on a tandem.
4. Barrelling downhill is not an option as my Stoker gets white knuckles and wet pants at anything more than jogging pace..... which is why her solo average speed is around 10mph..... her Strava PR's are being smashed on the tandem, even on flat sections !
5. I've adjusted the screws etc so I am happy with them, but I am expecting further cable stretch, and so will monitor the way they go and adjust as necessary.
6. I'll also persevere with the 52T for now as we're still getting used to riding the thing, but I am holding an option on changing the chainring for a 48T or 44T as you've suggested.
7. I'm going to fit a chain catcher on the seat tube, and possibly put a large cable tie on the chainstay to guide the chain away from the metalwork if it should ever come adrift again.

Thanks for all the help... I knew I'd come to the right place :-)

P

 

[si_c]

It's worth noting that unless there are huge gouges in the metalwork then any damage is likely to be just to the paint and therefore non-structural. You can make sure the paint damage doesn't get any worse or encourage rust by putting some clear nail varnish over the top.

The cable itself doesn't stretch at all, it's just all the parts bed in so small gaps get reduced and there is therefore slightly too much cable in the system - you can adjust this out with the inline adjuster that should be there, you can feel when there is too much slack in the cable as it doesn't feel taut when you put your finger on it when in the lowest gear at the front.

 

[raleighnut]

OK everyone, here's the denouement to this.... I had a long chat with the seller yesterday after sending them an email with pics etc. In brief:
1. They acknowledge the set screws were not correctly positioned when the bike left them.
2. They're confident the chainstay damage is nothing to worry about, and in any case, any further deterioration in time will be dealt with under their warranty.
3. They know the gearing set up is out of spec, but it's a configuration they have fitted many many times, and works reasonably well, given the wider range of gearing often necessary on a tandem.
4. Barrelling downhill is not an option as my Stoker gets white knuckles and wet pants at anything more than jogging pace..... which is why her solo average speed is around 10mph..... her Strava PR's are being smashed on the tandem, even on flat sections !
5. I've adjusted the screws etc so I am happy with them, but I am expecting further cable stretch, and so will monitor the way they go and adjust as necessary.
6. I'll also persevere with the 52T for now as we're still getting used to riding the thing, but I am holding an option on changing the chainring for a 48T or 44T as you've suggested.
7. I'm going to fit a chain catcher on the seat tube, and possibly put a large cable tie on the chainstay to guide the chain away from the metalwork if it should ever come adrift again.

Thanks for all the help... I knew I'd come to the right place :-)

P

I'd still sooner fit a 52-40-30 standard touring triple, I know you'd lose a bit of low gearing but shifting would not be compromised, also be aware that cable 'stretch' or settling will not be affected the front mech limit screws. The way to adjust the cable for any slackening is to increase the 'tension'* adjuster barrel, correct adjustment is when the chain is central in the mech when in the middle position and on the centre cog at the rear.

* I dislike the term 'cable tensioner' as in bottom the cable can often be slack, think of it more as a cable length adjuster.