DA7800- largest cassette?

[wpod]

My sister is considering an older DA7800 kitted bike with a compact crank and a SRAM 11-26 cassette. No experience with DA, can she run a 11x32? Any chance of a 11x36?

Thx

[zzy]

officially a 27t, but I've had luck with a 11-30. 32 may be a stretch depending on your hanger length.

[dave thompson]

Originally Posted by wpod

My sister is considering an older DA7800 kitted bike with a compact crank and a SRAM 11-26 cassette. No experience with DA, can she run a 11x32? Any chance of a 11x36?

Thx

You're in La Ventana? I lived in Los Barriles for a number of years.

To answer your question, pretty much the max cog size the 7800 rear derailleur can handle is 30t. If a larger cassette is wanted/needed, the simple solution is to install a Shimano 9-speed MTB derailleur. Then, depending on the exact model of the derailleur, up to a 36t cog can be used with no issues. This is a very common and easy thing to do.

[trener1]

I am still running 7800 on my primary road bike, was in this exact position recently, I bought a brand new 10 speed 105 rear derailleur and a 32 cassette, no problems at all.
You might be able to go up to a 34 with the 105 deraileur, I am not 100 percent sure.

[robt57]

Highly dependent on the RD hanger position and more-so length.

Google Wolftooth Road Link for some concepts on helping accomplish pushing it.

[dddd]

Originally Posted by robt57

Highly dependent on the RD hanger position and more-so length.

Google Wolftooth Road Link for some concepts on helping accomplish pushing it.

Back in the 10s era, it was not uncommon for even the 11-28t cassette to make for tighter maintenance requirements due to the B-screw having to be tightened so much.
Adding the Wolf Link would only further increase the chain gap distance over the smaller cogs.

A 12-30t cassette was the largest 10s road cassette that Shimano offered, and perhaps only for the later 10s Tiagra and 105 gruppos.

The 9s Deore derailers are made to handle the 11-34t and 11-36t cassettes that you could run on your 10s bike, and are compatible with the Shimano 10s road levers. Note that it's only the later Deore 9s derailers which are actually made for larger than 34t cogs.