Schmadley

I'm currently on a 2008 105 equipped bike (I think CS-5600), and am running the standard 53/39 crank to 11/25 cassette. I'm not having any problems with this set-up at all - the problem is more to do with the engine and getting up hills.

I'm thinking of changing the cassette to an 11/28 to see if this will help me at all. I think that this is the cassette used often in a compact set-up.

What I would like to know is if the Ultegra CS-6700 will be able to be used in conjunction with the 105 system that I currently have (105 front/rear derailleur and shifters/brakes). After the last service, I changed the chain to Ultegra, so I may have already answered my question, but need some help from the BF tifosi out there.

Thanks in advance.....

ericm979

It'll work.
You may need a longer chain. GENTLY shift to the large chaingring/large cog combination. If you need a longer chain it'll be obvious.

kayakdiver

If you're really having problems with hills... I'd suggest looking into a Compact 6700 Crank. Keep the standard for when you get stronger?

Gluteus

I have 2 cassettes (DA and 105) with the same cog combos that you mentioned.
I use both without problems. However I have compact rings (50, 34).

thesmoothdome

I'm running an 11-28 with an Ultegra standard crank, 105 FD, and Ultegra RD and will be keeping that gear ratio with my new bike. I did go with a SRAM cassette because I like the cog spacing better than the Shimano cassettes. SRAM upper 3 cogs are 22-25-28 while Shimano are 21-24-28.

Caracalla.

i had an 11/25 cassette and changed to an Ultegra 12/27. front is standard 53/39 crank. No problems on exisiting chain and did not even had to adjust the RD. It just fit in.

revchuck 

+1 on switching to a compact crank if the hills are giving you trouble. That's about twice the expense of a new cassette, though. Since the 5600 series of 105 has been discontinued, you might find a pretty good deal on a new/old compact crankset.

I'd advise going to a 12-27 cassette rather than an 11-28, unless you really need the 11 tooth cog. The spacing would be more comfortable IMO.

Schmadley

Thanks KD. Is this a more cost effective solution to what I proposed?

Thanks Smooth. This is an option that I hadn't thought of. Obviously, the SRAM cassette works with the other Shimano components that I am currently running. As mentioned in a previous post, will the chain length possibly need to be altered?

Thanks Caracella. Did this make a great difference with you? I like the 11 cassette for the descent. I seem to max out at about 64km/h even when pedaling furiously downhill on the steepest section of my normal ride, so if I can keep the 11, I'd like to. Here is the downhill section I am talking about - https://www.mapmyride.com/route/au/sy...28858091174627

thesmoothdome

I don't know. Any time I've changed cassettes I've also swapped out the chain.

Caracalla.

The speed difference between 11 and 12 is small. I dont have problems downhill using 53/12. When I had the 11/25 and going up steep hills, I always said 'if I just had one more ring', the 27 solved that. 39/27. You will find that the 12/27 is popular among bikers. The spread is good and mainly all-around usage.

My drivetrain is a soup. DuraAce Cranks, 105 RD, Ultegra cassette, SRAM chain.

Nachoman

I think the R700 compact cranks are less than $100.00.

scirocco

Your rear derailleur is theoretically not compatible with a 28 tooth cog, because it used to be that 27T was the largest rear cog that Shimano made in their road bike range. However, I have used the combination of 28T with an older RD and it works okay. The only drawback is that you have to have the B-screw wound all the way to avoid the 28T ring hitting the derailleur jockey wheel. This makes the shifting in other gears not as crisp as it might have been.

If you want to be sure that it will work without problems maybe consider an 11-27 rather than an 11-28 cassette.

znomit

Thats only a 7% climb. It will get easier with practice. Put the 27 on when your cassette is worn out.

djlarroc

This is what I want to do. Did you have any issues making that change? What sram cassette did you use?

Btw, if the crank is changed to a compact, what else is needed to change? Bottom bracket?