Hi

I’ve had mountain bikes for years and have always fixed everything myself, although this doesn’t mean I’m any good at it. In fact gears are a particular weakness.

I just got a nearly new road bike (first ever road bike) with an ulterga 6703 triple chainset. I can index the rear mech so it’s ok when the front mech is in either the two smaller rings or the two bigger rings. However, I can’t get it to work across the full range in all 3 rings. If I set it so that it’s right in the small ring at the back and the big ring at the front, by the time I get to the big ring at the back and the small ring at the front it’s well out.

There’s very little wear on the parts and I put a new cable (an ordeal with the road shifter) in which seems to be moving freely. I’ve set the b screw thing so it’s close to the sprockets (actually screwed all the way out now). I’ve made sure that I’m starting on the right gear so I’m not a full gear out or anything.

Any ideas please?

Did you build the bike? are you sure the chain line is OK are the HT2 spacers in the right place or if its an old square taper if its the right length?

A 6703 chainset is HollowTech II so uses an external road bottom bracket which shouldn’t have spacers.

I’ve found road triples much more of a pain to keep shifting well than mountain bike ones. I’ve had then on a few bikes and have usually switched to a compact instead of the triple.

Set the front mech first, small and big, then big and small. Once those combinations work then you can set the rear mech. Set the limits by pulling the cable rather than using the shifter, then use the shifters and the barrel adjusters to set the indexing. Park tools have a very good detailed guide on their website.

Thanks for your replies. I appreciate your help.

I worked my way through the Park guide and it’s the best guide I’ve ever seen. However, even after a few small tweeks I still have exactly the same problem where the rear indexing seems to be different for the largest and smallest front chain rings.

As mentioned above, there are no spacers so no option to adjust the chainline.

I’ve thought about changing to a compact/double but I wouldn’t want to go any smaller on the big ring and want to keep a small ring for cycling around the highlands.

Anybody else got any bright ideas? Might it just be that my frame (planet x nanolight) is only suitable for a double?

You’ll never get it perfect all the way down the cassette with a triple, the top end will never be right when in the granny ring and the big cog at the back will always be out when in the big ring. So long as they all work well when in the middle cog thats the best you can hope for really.

Fair enough thanks for setting my expectations. Makes me wonder what the point of a triple is then?

http://bike.shimano.com/publish/content/global_cycle/en/us/index/tech_support/tech_tips.download.-Par50lparsys-0025-downloadFile.html/01)%20Drivetrain%20Compatability%20Chart.pdf

http://bike.shimano.com/publish/content/global_cycle/en/us/index/tech_support/tech_tips.download.-Par50rparsys-0028-downloadFile.html/01)%20100%20Causes%20of%20Bad%20Shifting.pdf

Fair enough thanks for setting my expectations. Makes me wonder what the point of a triple is then?

To give you a wider spread of gears. It will also give you duplicated ratios if you try to cross the chain from large to large or small to small so try to avoid doing that.

Fair enough thanks for setting my expectations. Makes me wonder what the point of a triple is then?

You shouldn’t really run the chain on the smallest at the front with the largest at the back or vice versa. You’ve got 4 or may be 5 usable rear gears for each chain ring at most.

Mister P +1

Thanks for the further replies. I followed the park guide link near the top which was the best guide I’ve ever seen. I’ve had mountain bikes for years so I know about not crossing the chain etc.

I just can’t understand why the rear indexing on my road bike triple is so different for each of the front rings. Therefore, it’s impossible to use the easiest gear and the hardest gear on the bike without changing the indexing (quite a lot). Being 10 speed obviously makes things tighter.

Bluebird’s response explains the reality of the situation but it doesn’t make sense because if you don’t run the largest gear at the back with the smallest at the front then what do you run it with? Why is it there?

Think he meant small front, small back.

Use the 3 or 4 largest on the back with the small ring, 3 or 4 smallest on ther front with the large chainring, and pretty much owt with the middle ring.

You’ll never get it perfect all the way down the cassette with a triple, the top end will never be right when in the granny ring and the big cog at the back will always be out when in the big ring. So long as they all work well when in the middle cog thats the best you can hope for really.

Well, that’s rubbish. My Ultegra triple works fine in all ratios. You should at least be able to use the biggest 5 sprockets with the small chainring and the smallest 5 with the biggest chainring. It’s worth checking your front mech is dead parallel and not bent at all.

This should index fine across the block on all of the chainrings – even crossed over right at the limits (50/32 & 22/11 or whatever you have), although as you’ve already said – you won’t really want to be riding it very far on ratio’s like that …

Like Boriselbrus there ^ – I’d [also] suggest checking the alignment of the front cage too; actually, do that first, then …

Make sure that the rear cage isn’t bent / twisted / can cope with the range of gearing / has the H/L screws set properly, and that your hanger isn’t too far out of alignment, then …

Drop the chain onto the middle ring on the front, and then set up the indexing on the back. Cable tension will be quite critical – on a 10 you aren’t moving much with each click, so <1/16th of a turn might be enough to knock it out.

Double check that the new cable has fully located into the lever too – I’ve wasted ages in the past hunting for a random indexing failure when bike building, only to find it was down to the cable not quite being settled in place … 🙄