What is the maximum tooth sprocket you could fit on the back using a Deore DX rear derailleur?

[retrobiker273891]

I have seen quite a few threads relating to newer road bikes and how they are clearing 40-42t back cogs, some with the help of road links.

As I have read, generally the derailleurs are small to medium on road bikes.

For mtb, even the old ones, due to having 3x, I read that long cage is standard.

I know they say in their manuals no larger than a piddling 32t or so but that was when they didn't have bigger ones isn't it.

The size of the old 21speed rear derailleurs seem similar to the new dinner plate catchers so how big could they take do you think?

I would prefer not buy a new RD since they are expensive and hanger extenders are cheap so wondering what you could squeeze out of them.

If I get a bike with 8sp hub then all then all but the top of the line bleeding edge cassettes will be available to me. So I am wondering what the RD could handle, granted with a hanger extender.

 

[hamster]

Probably 34T, but it depends on the hanger length on the frame. It will be more if you fit a goat link.

The span depends on the angle of the parallelogram, not the cage length, which determines the amount of tooth difference that can be accommodated.

Honestly, you are massively overthinking all this. Give it a try.

I also think that your quest for ultra-ultra-low gears is pointless. The bike will be going so slowly it will be hard to balance. Furthermore, you will not be able to start in such low gears, as the bike will move forward only 50cm in the starting stroke and you will not have enough momentum to balance.

 

[Gtpulse]

The cheapest/easiest way to overcome the issue of getting up hills more easily is to get more hills in to your legs on whatever bike you have to hand. Even doing part of a hill or less steep hills more regularly will help massively.

I get that there is theoretically some mechanical advantage with some variation to gearing and geometry. Even if you achieved perfection in this respect it’s only going to be ok for a short while then you’ll wonder why you needed it at all.

Buying stuff at the moment is relatively low risk, prices are as low as they have been for retro stuff if it’s selling at all. Worst case you’d get your money back if you needed/wanted to sell later down the line - new stuff not the case. I buy stuff, try it out and sell it on if it doesn’t suit what I need or I don’t want to keep it for a future build.

 

[retrobiker273891]

Probably 34T, but it depends on the hanger length on the frame. It will be more if you fit a goat link.

The span depends on the angle of the parallelogram, not the cage length, which determines the amount of tooth difference that can be accommodated.

Honestly, you are massively overthinking all this. Give it a try.

I also think that your quest for ultra-ultra-low gears is pointless. The bike will be going so slowly it will be hard to balance. Furthermore, you will not be able to start in such low gears, as the bike will move forward only 50cm in the starting stroke and you will not have enough momentum to balance.

Buying stuff at the moment is relatively low risk, prices are as low as they have been for retro stuff if it’s selling at all. Worst case you’d get your money back if you needed/wanted to sell later down the line - new stuff not the case. I buy stuff, try it out and sell it on if it doesn’t suit what I need or I don’t want to keep it for a future build.

Yes I see this is a bad idea now, that is, trying to mix new cassettes with old stock. I run up against the wall of the old tech not being compatible with the newer large cassettes.

As such I am thinking just stick with even 7s hub and max it out with 34t and instead focus on smaller chainrings as they are cheaper than new rear mechs and cassettes, and are compatible because they are of the same period.

 

[Tsundere]

The cheapest/easiest way to overcome the issue of getting up hills more easily is to get more hills in to your legs on whatever bike you have to hand. Even doing part of a hill or less steep hills more regularly will help massively.

This.
Unless you have a motor fitted you are the propulsion unit for your bike. Assuming the bike is set up as well as it can be, with decent ratios, all bearings running smooth and wheels spinning true, the only place left to work on is your strength and endurance.

Regularly challenging yourself plus the right nutrition will remedy this in short order.

 

[retrobiker273891]

This.
Unless you have a motor fitted you are the propulsion unit for your bike. Assuming the bike is set up as well as it can be, with decent ratios, all bearings running smooth and wheels spinning true, the only place left to work on is your strength and endurance.

Regularly challenging yourself plus the right nutrition will remedy this in short order.

So never upgrade a bike. Stick with single speed and 'mash' up all hills. .

 

[Tsundere]

So never upgrade a bike. Stick with single speed and 'mash' up all hills. .

No, get the bike set up as well as it can be, if you do that and you're still struggling then you're the bottleneck.

Most of us here are on the wrong side of 45, so none of us are as fit as we once were. Maintaining strength and endurance the best you can will do more for your ability to continue enjoying your bikes than any upgrade.

Fitness and upgrades is optimal.

 

[W7Ford]

Out of interest how many teeth are you running on the front chainring retrobiker273891? This is something that I'm guilty of serially tinkering with.

 

[retrobiker273891]

Out of interest how many teeth are you running on the front chainring retrobiker273891? This is something that I'm guilty of serially tinkering with.

I am 1:1 right now at 28/28x26.

I noticed last ride it is getting noticeably easier but still I want the option of lower gears if I want them if there are serious and/or long inclines and just want to amble up them.

Just like on a car you don't expect to use 1st gear all the time, but it is there, besides other uses, for serious slopes.

 

[retrobiker273891]

Buying stuff at the moment is relatively low risk, prices are as low as they have been for retro stuff if it’s selling at all. Worst case you’d get your money back if you needed/wanted to sell later down the line - new stuff not the case. I buy stuff, try it out and sell it on if it doesn’t suit what I need or I don’t want to keep it for a future build.

On a side note, why is the market this way at the moment? I only just came into this community so have no reference. Is this different to other periods and if so what has precipitated it? Brexit. Cost of living? Usual two culprits people state for most British problems. Oh immigration is the hot one right now .