Bigger Rings on Triple DA

dazman said:

I've got a triple DA crank on my training bike I bought for the mountains. I actually now need an option that allows me > 53 on the biggest ring for online TTs I'm doing. Does this exist even from custom guys as I cannot immedietly see as standard from online retailers.

Otherwise, is there any way to convert this to a double crank, ie just an outer 42/55 ring?

COLORADO CYCLIST (coloradocyclist.comcoloradocyclist.comOpen ↗), amongst others, sells Shimano TT rings in the size you want [55t & 56t] ... so, ANY major online seller OR your LBS should be able to get one for you. They are exceptionally expensive (~$130US ... probably, MORE at your LBS!?!) because they are "Dura Ace" rings:

[center][img]coloradocyclist.comssbikwhj.jpgOpen ↗[/img][/center]

FSA also makes TT rings. I don't know how much they cost.

You should be able to simply swap whichever tooth count chainring you get with the 53t and not encounter any shifting problems ... especially, if you are using bar end shifters.

VUELTA used to make 55t (and, other size) 130BCD & 135BCD rings ... but, they may not be ramped since they will probably be old stock. With bar end shifters, shifting may be "okay" ...

You can substitute the middle ring with a standard chainring, but you obviously loose the granny tabs.

Whether or not you want to change the BB (I'm presuming you have a 7703 crankset) is up to you. I found that an 112.5 XTR BB will work with either a double OR triple (on a steel frame) Octalink ROAD crankset ... the XTR spindle fits inside the "older" DA Octalink BB shells (and, all of the Italian threaded DA Octalink bottom brackets, AFAIK) ... OR, you can simply put a ~2.5mm spacer on the driveside (the XTR BB comes with BB spacers to allow you to use them with either a 73mm or 68mm BB shell).

alfeng said:

COLORADO CYCLIST (coloradocyclist.comcoloradocyclist.comOpen ↗), amongst others, sells Shimano TT rings in the size you want [55t & 56t] ... so, ANY major online seller OR your LBS should be able to get one for you.

Cheers. I have a DA 55T and 42T set (B type I think) from my double TT setup, but do these work okay on the stock triple? Then I guess I need a 33T inner ring - does this exit?

dazman said:

Cheers. I have a DA 55T and 42T set (B type I think) from my double TT setup, but do these work okay on the stock triple? Then I guess I need a 33T inner ring - does this exit?

I don't see any reason why you couldn't mount your current DA TT rings on your DA's triple crankarms ... the DA 7703 spider is PISTA-like in that it doesn't have inner shoulders on which the inner ring seats, but the shoulders aren't truly necessary on any crank UNLESS you lose a couple of chainring bolts during a ride.

However, you cannot maintain the DA 7703 triple crankset as a triple if you want to change that 39t middle chainring to another Shimano-brand chainring ... the middle/granny chainring combination is theoretically proprietary to that crank UNLESS you were to remove the inner "shoulder" tabs on another crank's spider; and, there were no other combinations.

Normally, if you want an Octalink TRIPLE crankset onto which you can mount something other than the middle-granny combination you find on the DA 7703 crankset, you need to buy either an Ultegra or 105 Octalink TRIPLE crankset.

There ARE 33t 74BCD chainrings ... usually used on Tandems. 32t is more commonly available size, I think, and I doubt that the difference in circumference is great enough to affect shifting.

There is NO from-the-factory, Shimano chainring option to the DA triple. However, you can substitute a TA Triplizer inner ring (there may/[must] be a 42t version) ... IMO, 99% of the time, this would only be done as cosmetic issue where you want to maintain a DA crankset UNLESS your cranks have 180mm arms OR you wanted a different sized granny.

FWIW. IMO, it would definitely be less expensive to get an Ultegra 6503/Triple crankset if you want a 55/42/32-or-33 combination.

NB. Since the granny you want to use is fairly large, a much less expensive alternative to the TA Triplizer would be a BMX chainring which has both 130BCD & 110BCD mounting holes. The BMX ring won't be ramped; but, I'm not sure that the TA Triplizer is, either. The BMX ring will be heavier than the TA Triplizer, too.

TA makes 33t 110BCD rings ... of course, 34t 110BCD rings are more commonly available.

Great thanks for the comprehensive reply, sounds like a weekend experiment

On this basis though:

alfeng said:

However, you cannot maintain the DA 7703 triple crankset as a triple if you want to change that 39t middle chainring to another Shimano-brand chainring ... the middle/granny chainring combination is theoretically proprietary to that crank UNLESS you were to remove the inner "shoulder" tabs on another crank's spider; and, there were no other combinations.

I may just try the 55 outer ring. I guess the 39/55 jump is going to be a little grumpy, or Shimano would not sell the 42 as the complement, but for my all out TT efforts I will only be in the 55 all the time anyway.

Cheers,