52/38/28 Tiagra Triple - Advice Please

[Paul Walters]

My wife and I have an Orbit Velocity Tandem fitted with 3x10 Tiagra with 52/38/28 chainrings. I managed to drop the chain off the small chain ring yesterday resulting in some deep scuffing on the driveside chainstay, which I'm hoping is mostly in the paintwork, and the result of inexperience and sloppy changing, BUT, when I was fettling with it earlier today, I noticed that the inner face of the 52T ring is getting scuffed by the chain as a result of changing gear. The front mech is obviously deep enough to make the 14T shift between the rings, but is this sort of damage normal wear for a triple? With the bike in the workstand, and turning the pedals by hand, the friction caused by the chain jamming against the ring and mech cage is enough to stop the thing dead.

I have a 3x9 XT/Deore 44/36/26 set up on my Dalesman and I've never noticed this level of scuffing before.

We've had the bike some months, but due to an injury I had, and then the rainy weather over the winter, we've only actually ridden it in last week or so. We've put around 100miles into it, so I imagine the cables are now stretching in somewhat too, which might explain the missed gear change?

Any thoughts on the wear on the rings anyone ?

 

[raleighnut]

Are the shifting pins on the sprocket OK or worn.

 

[Paul Walters]

The bike's only done about a 100miles from new, so I can't imagine there's any wear on any of the components, so I'm assuming they're in near perfect condition.

 

[CXRAndy]

Normal wear pattern. The chain is forced against the inside of the bigger chain ring when up shifting. When a lift pin rotates into position the chain completes the lift onto the teeth

 

[Paul Walters]

There are no pins on the inside of the big ring, or even a sign of where one might have been, so I'm not sure now what I'm looking for. I'll check the triple on my wife's roadbike and my tourer in the morning.

EDIT.... checked in daylight, and there are "studs" rather than "pins" on the inside face of the ring...

 

[Ajax Bay]

The front mech is obviously deep enough to make the 14T shift between the rings
I imagine the cables are now stretching in somewhat too, which might explain the missed gear change?

What make/model is the FD please? FD-4703? Its spec is a 20t range and you are asking it to do 24t.
I am aware that it will manage that, but there may be a struggle (read scuffing) to climb onto the large (52t) ring.
I note your Dalesman's range is only 18t.
Inner cables do not 'stretch' (<0.001%). Dropping the chain off the inner will not be dependent on cable tension: this should be prevented (or at least the risk should be minimised) by correct setting of the L limit screw.

 

[Paul Walters]

Hi AjaxBay,

The FD is a Shimano 105 but the rest of the set up is Tiagra 3x10. I've checked the inside face of the chain ring, and there are studs there to catch and lift the chain on the upshift, but the whole movement is sluggish and imprecise. Last night, after reading some replies I checked the movement of the FD by pulling the cables directly, and found I was able to pull the chain straight over the top of the big ring and onto the crank! It looks as if the FD has been set up so it "hangs" on cable tension rather than being controlled by the stop screws. At least that would explain how we dropped the chain against the chainstays if the cable tension is relaxing as it stretches and beds in.

Like I said above, the bike was bought brand new last October, but hasn't been ridden until the last week or so. We've been out half about half a dozen times and covered about 200km on it.

Cheers
P

Attached pic of the damage to the chainstay. I'm hoping this is nothing to worry about.... I'll get the FD set up sorted either myself or via the LBS....

 

[Ajax Bay]

I have dug out the relevant tech spec for an FD-4703 and it offers the table below (4th column). The spec for an FD-5703 (105) is the same (NB designed for an 11sp chain).
https://productinfo.shimano.com/#/spec/ROAD/Front Derailleur
You have shared that your chainset is 52-38-28. As you can see the tandem has been equipped with 'out of spec' chainrings on two counts: 24t range when spec is 20t; and a 14t delta mid-top when the spec is max 11t. An in-spec triple of rings would be 50-39-30. I don't know what cassette/RD you have fitted, but I suspect that the chainring range (24) and the cassette range (eg 11-30) means that the combined total (43) is outside the RD spec.
https://productinfo.shimano.com/#/spec/ROAD/Rear Derailleur
You may wish to ask the (recent) seller of your tandem why they have fitted out of spec (for both your FD and RD) chainrings. Imo you cannot reasonably need a 52t on the front with an 11t on the back. I would be tempted to replace the 52t with a 48t back into spec, and probably solve your issues.

Chain line (mm)	43.5	43.5	45	45
Chain stay angle (deg.)	61 - 66	61 - 66	63 - 66	63 - 66
Top gear teeth	46-52T	46-52T	50T	50T
Total capacity	16T	16T	20T	20T
Applicable Top-Mid tooth difference	-	-	11T	11T

 

[Paul Walters]

Hi AjaxBay,

Thanks for such a detailed reply; it certainly looks like the gears are out of spec. This might be partly my fault though, as when we specified the tandem make up, I was keen on a low "bottom end" gearing ratio as I anticipated carrying some weight on a 3-month long tour, and I felt my wife (who is tiny) would benefit from the lower gearing.

We bought the tandem off a specialists supplier in Yorkshire, and we we spent almost the whole day test riding and discussing the build with them. They were very obliging with customizing the build, but didn't at any stage suggest there might be a problem with the gearing we required.

I'll have to have a serious think about where I go with this, as there is the potential for the damage to the frame being a warranty issue (due to incorrect set up of the stop screws), as well as the argument about a non-compliant spec from the customer (me). Plus, any additional cost in changing the chain-rings to a compliant system, returning the bike for repair, or the buggerance in fettling it all into working order.....

Here's the full set up, you can also see the position of the set screws...

 

[Ajax Bay]

The limit screws are set where you have them. Your call to screw the lower (L) one in a tad.
My recommendation is to speak to your seller and enquire why they fitted a chainset clearly out of spec, without telling you that, and see if you can score/swap a 48t ring off them (even a lightly used one). If your requirement was a 'low bottom end' I can see no reason why a 52t was fitted. The 52t ring has no relevance to low gears. 130mm BCD and (I think) 5 bolt.
As an observation (and based on your image), your FD is set too high: the gap between the bottom of the cage and the top of the large ring's teeth should be 3mm max and better 1mm - 2mm. This might (also) improve shifting to the large ring.
ETA: Let's have an image of the RD cage with the chain on large and large, and another on small and small, please. What is the cassette range 11-32?

 

[raleighnut]

Well all 3 rings seem to come from different makers to my eye at least

 

[Paul Walters]

I think they do. The middle ring had no discernible makers mark. I counted the teeth physically.

 

[Paul Walters]

The limit screws are set where you have them. Your call to screw the lower (L) one in a tad.
My recommendation is to speak to your seller and enquire why they fitted a chainset clearly out of spec, without telling you that, and see if you can score/swap a 48t ring off them (even a lightly used one). If your requirement was a 'low bottom end' I can see no reason why a 52t was fitted. The 52t ring has no relevance to low gears. 130mm BCD and (I think) 5 bolt.
As an observation (and based on your image), your FD is set too high: the gap between the bottom of the cage and the top of the large ring's teeth should be 3mm max and better 1mm - 2mm. This might (also) improve shifting to the large ring.
ETA: Let's have an image of the RD cage with the chain on large and large, and another on small and small, please. What is the cassette range 11-32?

RD pics attached. Cassette is 11-33.

 

[Ajax Bay]

The images show that your RD is being asked to perform beyond spec and at the limit of its capacity. Unless you can see a '33' stamped on the largest sprocket, I suspect the cassette is actually 11-32 (which is noted as the upper limit for the RD-4700, but that assumes a 20t range on the front. My recommendations above are unchanged. Best of luck and I hope you can enjoy some good rides together, all three of you.

 

[Paul Walters]

Cassette is definitely 11-33. The large sprocket is stamped 33.
I'll speak to the shop, explain the difficulties we're having, and hopefully they'll be able to suggest something FOC.
Thanks for all your help. 👍