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View Full Version : Crank/Gearing Advice Wanted (DA 7800 specific)


n_maher
08-19-2014, 08:37 AM
So I've been riding my Calfee for about a year now and while it's near perfect for about 95% of the riding that I do there's 5% that it just doesn't do well, specifically steep climing. Now part of that is me but there's not much that I can do about that. I don't have the time to ride more, I just want to be able to enjoy what I ride when I can. So the nuts and bolts are this: the bike is currently running full DA 7800 with a 53/39 front, 11-25 cassette, short cage RD. I'd like to change either the crank or cassette to get a little more overall range. I'll never get to the compact 50/34, 11-32 that my Roubaix had but that bike almost never saw the little ring. I've done several searches here and elsewhere trying to find setups that will be largely compatible with what I've already got and I can't seem to figure it all out, hence this thread. I have determined that I can go as large as a 28 on the rear without changing anything so this really boils down to two crank-related questions.

1. Are there midcompact rings that are compatible with my existing crank? I think if I got to a 52/36 setup and left the cassette alone I'd be pretty happy.

2. Who makes a traditional compact crankset that is compatible with my existing BB?

Thanks in advance,
Nate

oldpotatoe
08-19-2014, 08:56 AM
So I've been riding my Calfee for about a year now and while it's near perfect for about 95% of the riding that I do there's 5% that it just doesn't do well, specifically steep climing. Now part of that is me but there's not much that I can do about that. I don't have the time to ride more, I just want to be able to enjoy what I ride when I can. So the nuts and bolts are this: the bike is currently running full DA 7800 with a 53/39 front, 11-25 cassette, short cage RD. I'd like to change either the crank or cassette to get a little more overall range. I'll never get to the compact 50/34, 11-32 that my Roubaix had but that bike almost never saw the little ring. I've done several searches here and elsewhere trying to find setups that will be largely compatible with what I've already got and I can't seem to figure it all out, hence this thread. I have determined that I can go as large as a 28 on the rear without changing anything so this really boils down to two crank-related questions.

1. Are there midcompact rings that are compatible with my existing crank? I think
if I got to a 52/36 setup and left the cassette alone I'd be pretty happy.

2. Who makes a traditional compact crankset that is compatible with my existing BB?

Thanks in advance,
Nate

1. No, smallest small ring is 38t for that crank


2. Shimano. Get an Ultegra or R700 compact crank(or 105 level), buy some 110bcd rings for it of your tooth choice and bob's yer uncle.

macaroon
08-19-2014, 09:19 AM
Stick with the DA crank, the new shimano models look rubbish in comparison.

Get a 38tooth ring if you want, and combined with a 28tooth cassette, it would do you fine I reckon.

I also reckon you won't have any problems running a 30tooth at the back, but you may need a longer b tension screw for your mech.

Look585
08-19-2014, 09:34 AM
I run a 12-30 in the back with my 7800 53/39. Works fine. I've pushed it to a 32 on occasion and not hit any snags.

Both with a normal SS rear derailleur.

n_maher
08-19-2014, 09:52 AM
Thanks for the input, guys.

Current line of thinking is to switch the front to a 52/38 setup and change the back to a 12-28. I think the easiest option for the back is an Ultegra 10spd 12-28 so that's the direction I'm leaning for that. Last question - I know that I can get a stock 52T DA ring but any recommendations for an aesthetically pleasing 38T to match?

LJohnny
08-19-2014, 10:21 AM
Nate, Depending on your derailleur hanger (the longer the better), you could get away with the 30 in the back. You just have to try it and see if it works. The b-screw will allow you some room. It can be reversed as well, for a bit extra space.

You'll probably need a new chain as well.

Good luck

shovelhd
08-19-2014, 10:26 AM
Another option would be to keep the standard and change the RD to a 105GS of the same vintage. It will match well with 7800. You should be able to run a 32 or maybe even a 34 with that.

n_maher
08-21-2014, 12:30 PM
Still looking for any thoughts/suggestions on a specific 38T ring that'll at least half match the standard DA rings. I'm hoping to order the rings and cassette before the end of the week and have severely limited search abilities at work.

Thanks in advance!

Ralph
08-21-2014, 12:33 PM
Not sure you'll notice the very small change from 39 to 38. Do rear first, then see if you need more.

n_maher
08-21-2014, 12:55 PM
Good point. The real issue here is that I'm running out of time before a century in less than 3 weeks with 6,000 feet of climbing. I've done it twice on the Roubaix without issue and would prefer very much not to suffer this year.

Ralph
08-21-2014, 01:18 PM
I would put a big tooth cassette on rear, and if that's not enough, just put a compact 34-50 on it. Going from 39 to a 38 is so small (2.5%), it's a waste of money. Going from 25 to a 28 tooth cog in rear is 12% lower, and from 25 to 30 in rear is a 20% lower gear VS 25 tooth cog in the 11-25.

Look585
08-21-2014, 03:12 PM
12-30 cassette is your best option. 98% sure it will work with an otherwise stock setup. Probably with a slightly longer chain. You should fit a new chain w a new cassette anyway.

Ultegra about 75$ for the cass+chain.

Sent from mobile device

Dead Man
08-21-2014, 03:19 PM
Good luck trying to find a compact Dura Ace crankset in anything but 175mm cranks, though. I can't find a 10-speed compact in 170mm to save my motherbleepin life, for any price, new or used.

LJohnny
08-21-2014, 03:31 PM
At this point if it were me, I'd try the 12-30 cassette first...

oldpotatoe
08-21-2014, 04:25 PM
Good luck trying to find a compact Dura Ace crankset in anything but 175mm cranks, though. I can't find a 10-speed compact in 170mm to save my motherbleepin life, for any price, new or used.

Where ya lookin, MO/online/inter web?

Any bike shop that has a QBP/J&B/E-A/Hawley/SBS, etc, can get a variety of 170 compact cranks.

palincss
08-21-2014, 05:06 PM
Good point. The real issue here is that I'm running out of time before a century in less than 3 weeks with 6,000 feet of climbing. I've done it twice on the Roubaix without issue and would prefer very much not to suffer this year.

So what's wrong with using the Roubaix this year?

roydyates
08-22-2014, 07:50 PM
I run a 12-30 in the back with my 7800 53/39. Works fine. I've pushed it to a 32 on occasion and not hit any snags.

Both with a normal SS rear derailleur.

12-30 cassette is also my solution with a 7800 crank. 39/30 is about halfway between 34/27 and 34/25.