Originally Posted by
Kapusta
That old 8 sp RD should work fine with what you initially proposed. It will work with the 105 shifters.
However, going to a wider range cassette you will start to run into issues with exceeding both the max cog size as well as chain wrap capacity of the old RD.
No, Obeast won’t run into problems. The Deore LX was built for exactly the kind of range that he is looking at. In fact it was built for a wider range. The era of the 8 speed LX overlapped with the era of 58mm BCD inner cranks which are capable of using a 20 tooth inner ring as well as a 34 tooth gear on the cassette. It’s fully capable of handling the range.
Originally Posted by
Obeast
hey guys thanks for your inputs. I have 10 speed 105 shifters but I think I will go with friction shifters for the 22 front and 32 rear. My plan is to use a vintage 8sp Deore LX rear derailleur I have in my parts bin. Is it possible to go even higher than 32 tooth cog, like 34 to 40 with a 22 front chainring? Is that even mechanically possible?
Go with the 105 shifters. The 10 speed 105 is still capable of shifting 9 speed (or 8 speed) mountain bike derailers. You will have to be clever with the front derailer because the 105 will only shift a road front derailer. The good news is that Shimano’s cheap road front derailers excell at this task...much better than the more expensive ones. An older Tiagra or a newer Sora will do the job nicely.
I have used 10 speed shifters with mountain derailers. I also have older mountain bike derailers working on wider gear ranges than you are proposing. Previously, I’ve had a 46/36/20 crank mated to an 11-34 9 speed cassette on my touring bike. With the addition of a Wolf Tooth Road Link, I’ve been able to put an 11-36 cassette on it without issue. That a much wider range then you are proposing.
On a separate not, you can even fit a 20 tooth cog to a 64mm BCD (which is what your crank has) with some surgery. I used this
to modify a Shimano crank to fit a 20 tooth inner on one of my mountain bikes. I used it yesterday on a mountain bike ride and it worked flawlessly.