claulo

Hello
I have a question about the product "Woolf tooth tanpan" Can I use a road rear derailleur, with MTB levers, if I use the tanpan??? Or does it only work the other way around?


Thank you in advance
​​​​​​​https://www.wolftoothcomponents.com/products/tanpan

Bill Kapaun

Considering the price of the Tanpan, why not just get a correct RDER?


I would think you'd have to install it "backwards" to change the pull ratio to what you want.

Duragrouch

I looked at the link. Interesting, learn something new every day. I've only seen such devices to mix short and long-pull brake levers and brakes. Going the opposite way from intended... hmm... it's a reciprocal relationship... link says it "amplifies road shifter cable pull", that makes sense, as a mountain cluster I would think would be wider. I think the relationship should work in the other direction as well, *mathematically*, however I don't know if the cable fittings will allow you to do that. Can the cable adjuster be moved to the other side?

dsaul

Just get the right rear derailleur.

The benefit of the Tanpan is being able to use an MTB derailleur on a gravel type bike with drop bar levers. This way you get the wider range and clutch of the MTB derailleur with a drop bar lever.

There is no benefit to going the other way.

Duragrouch

Knowledge. I love it when someone has a perfect thread-killer answer.

grumpus

I'm not familiar with that particular product, others of the same type have alternate cable positions to allow them to convert in either direction, the instructions for the Tanpan don't mention an alternate position. But anyway they tend to add slop and sponginess to a system, so I wouldn't recommend their use if there was a reasonable alternative.

oldbobcat

No, it should not work the other way around. Think about it. Does multiplying by a fraction give you the same result as dividing by a fraction?

Bill Kapaun

NO, should NOT means YES.

You are either dividing or multiplying BOTH either way you use it.
It's just that in one direction it's by a number >1 and the other way <1.

Duragrouch

While it seems what the OP wants will not work and is not recommended, from a ratio standpoint, it should be valid. I think you are confusing this with the following frequent math issue:

You have $1.00, and reduce it by 10%, so you now have $.90 . Now you take that $.90 and increase it by 10% and you only get $.99, you don't get back to where you were originally, even using the "same" (perceived) percentage.

But in this case, let's say a 2:1 change in ratio:

1" pull x 2/1 = 2"
Reversing that, 2" pull x 1/2 = 1"
Completely reversible, mathematically.

choddo

1.2x = 1/ x /1.2 so if you can connect it in reverse, it should work. Bet you can’t though.

kcjc

I'm not commenting on how pulleys work or the statement's applicability but on the math. 1 x 1/10 is not the same as 1 ÷ 1/10. The first gives you one-tenth, and the second is 10. This is third-grade stuff- pulleys, mechanical advantage, high school physics.

choddo

Yes, exactly right, which is why the ratio change would work in reverse if it's practically possible.

Mtracer

I've used a TanPan specifically to run an MTB derailleur on a gravel bike. It worked very well. I think it is possible to use it the other way around. Though I agree with others, why? Since the TanPan is a significant fraction of the cost of an okay derailleur. I'll assume the OP happens to have an unused road derailleur. Or is switching out drop bars for flat bars and the associate change in shifters. If that, I'd just get the MTB derailleur and be done with it.

The ratio thing is going to work fine if you reverse it. Regardless of the confusion some here are having with the math, think of it this way. If on one side a road shifter pulls the cable the correct amount and on the other an MTB gets pulled the right amount, the reverse is clearly true since an MTB shifter matches and MTB deralleur and the same for road derailleurs and shifters.

The issue is mechanically orienting the TanPan. It would have to be physically reversed. As it is, the derailleur side of a TanPan is designed like the end of a cable housing to mate directly to the derailleuer. While the other end has a barrel adjuster. This cannot be switched. I think what you would have to do, is get the TanPan inline adapter. and then run a short cable from the TanPan to the derailleur. This would put the barrel adjuster on that short side. Which is a little odd, but should work.

So, I think it is doable, just a little weird and seems more trouble than it is worth to me.

Camilo

Is this thing anything like a JTek shiftmate?