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Dura Ace 7800 triple crank change

by richardelliott
Wed, Mar 25, 2015 12:14
14

I want to change my DA 7800 TRIPLE cranks from 175 to 170. Getting hold of the triple crankset is not proving easy. Will a 7800 double crankset work? Can I bolt the triple rings onto a double crankset? I havn't got my bike with me to check this but suspect it might be possible if the granny ring hangs off the middle ring rather than off any part of the crank. Grateful for any thoughts.

If you're new please join in and if you have questions pop them below and the forum regulars will answer as best we can.

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14 comments

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Derny | 9 years ago
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I love my 7803 crankset (180mm baby!) but if I wanted a different arm length, I would just buy the new Ultegra model.

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harman_mogul | 9 years ago
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All 7800 chainsets look great. The high-gloss dark silver finish is as good as it gets. Same for the DA hubs of that generation.

Oh, correction: I see you want to come down from 175 mm, not 172.5 mm, yes that does make quite a difference...especially if you use mudguards!

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harman_mogul | 9 years ago
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You can't convert the 7800 race double or compact double to the triple. The 30T granny ring bolts directly to the crank, so you must use the 7803 crank. This is not easy to come by, as you have found. Somebody, somewhere will have NOS if you are prepared to keep on looking.

Alternatively, Bike24.com has the 170-mm 6703 crankset in silver for €160. This will plug straight in. They also have the R563 crankset for half that price and you can mount the DA rings in place of the supplied SG-X rings.

It's a lot of trouble to lose 2.5 mm from your cranks...but if you must change them, PM me and will make you an offer for the outgoing 7803 set!

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richardelliott replied to harman_mogul | 9 years ago
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That is fantastically helpful and thanks. I think for now I'm going to keep eyes open for second hand 170mm 7803 cranks. As you say surely they must be out there. I did see a set on ebay that went for a crazily high price, I think near £400. I don't see how anyone would justify that with new dura ace at full set at £1k. Really appreciate the trouble you've taken.
Do you agree the 7803 dura ace looks more beautiful than the the more recent versions? I once read somewhere that campagnolo made beaufiful things that worked and shimano made things that worked beautifully. Some truth in that I expect but the 7800 dura ace is no ugly duck.

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IanEdward | 9 years ago
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Sorry, haven't checked all the details of your post, but I got a spangly new Ultegra triple off Planet X for £140, think it was only 172.5 though.

Just measured mine and the axle is 110mm from the tip of the non drive side splines to the inside of the black ring that sits under the granny. Hope that helps.

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richardelliott | 9 years ago
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Thanks and I'll look on those sites. My rings are ok luckily, my motive here is just shortening the cranks for the benefit of my creaking knees.

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bashthebox | 9 years ago
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Well, it's always worth looking/asking on the classifieds on lfgss.com or bikeradar; they're a lot more active than the road.cc classifieds. Bear in mind that having bought a used crankset, you might well need to spend as much again on new rings...

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bashthebox | 9 years ago
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My winter bike (i know, I know, stupidly overspecced but it was all second hand) is 7800 with a 6750 crankset. To be honest I can't really tell the difference between that crankset and the 7950 on my summer bike.

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richardelliott replied to bashthebox | 9 years ago
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Thanks for that. No need to apologise for over speccing here, youre amongst friends I expect! I'm sure I couldn't tell either. I have a slight preference though for maintaining the groupset vintage throughout, really just aesthetically. Wouldn't die in a ditch to do so but a preference.

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bashthebox | 9 years ago
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Wouldn't work with the shifters, as far as I'm aware. You can use an Ultegra crankset though, think you should be able to get a 6700 triple.
http://www.wiggle.co.uk/shimano-ultegra-6703-hollowtech-ii-triple-chainset/
See?

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richardelliott replied to bashthebox | 9 years ago
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Thanks for all the advice. With a whole new ultegra set being about £475 now I think that might be the answer in due course. Meanwhile I'll keep looking out for second hand dura ace chainset. Seems a crime to retire that superb dura ace when all I want is 5mm off the crank length.

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therevokid | 9 years ago
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from what i remember triple cranks have a 5 or 6 mm spacer on the drive side
and 3mm one on the non drive. This would push the drive side out far enough
for the 3 rings. i don't think the double axle would be long enough to accept
this spacer AND still have enough spline available on the non drive side.

i don't have a shimano double set handy to measure I'm afraid ...

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therevokid | 9 years ago
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isn't the crank axle longer on the triple hence the spacers either side ?
this would mean that using a double is unlikely to give you enough clearance
on the chain stays

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richardelliott replied to therevokid | 9 years ago
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Quite possibly although dont know how to check axle length without buying one to try.

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