Medic Zero

I'm toying with the idea of trying out the Mountain Tamer Quad chain-ring set-up:
https://abundantadventures.com/mt_plus.html

Curious if anyone has tried it and if so what front derailleur you used. I've got to replace my front derailleur (munched it mountain biking) and have a couple of Sun Tour friction shifters kicking around...

This is for my touring rig ('88 GT Timberline) that I am looking at taking through some very hilly country later this month, but I also use the bike as my daily commuter where I do some long descents and am mostly in my big (currently 53 tooth) chain-ring throughout the 7 mile (each way) commute. I'd like to retain the high-end speed capability but add a super low end (20T) to handle hill climbs while loaded for touring - hence the interest in the Quad.

fuzz2050

I actually just picked one up. I haven't had a chance to use it though, or even really a notion of what to do with it. It does look really cool.

Medic Zero

Well do keep us updated! I think I am going to go ahead and order mine when I get paid Friday. Unfortunately it probably won't come before I have to work for seven days in a row so I am going to have to hope that it works right when I mount it as I won't have any time to fiddle with it or change components before I leave town the day after that. Hopefully I'll be able to report that it worked and kicked the hills of northwestern California's rear end!

Hopefully the manufacturer has some recommendations for a front derailleur.

strock 

I've not used a Quad or Quad Plus, but I have used a Mountain Tamer Triple. I did try to set it up as a quad, which you can do by simply mounting it inside your original inner chainring. I never quite got it to work as a quad (20-30-42-52). When I initially installed the MT and 20t ring, the ring was so far inboard that my FD (Shimano Sora) couldn't travel in far enough because the seat tube and clamp got in the way. When I went to a longer BB spindle in order to move the rings outward, then the FD didn't have quite enough throw to move the chain onto the large ring. There might have been a "sweet spot" where the inner ring was far enough out and the outer ring was far enough in, but I couldn't find it. Of course, the truth is that I didn't look very hard. Instead, I simply used the MT as a triple (20-34-48), since that gave me the low that I wanted and a high that I found satisfactory. I'm guessing that if you play around with BB spindle length and try a couple of different derailleurs, you'll find something that works. Unfortunately, I can't tell you what it will be. But, if you want to run a 20t small ring and a 53t large ring, in addition to the issue of finding an FD that will travel across four rings, you also have to consider two additional factors: (1) the chain wrap capacity of your RD, which is probably a max of 45t or so, and (2) the cage length on your FD. If you set the FD high enough to clear the 53t ring, there is a good chance that the chain will rub on the bottom of the FD cage when you are on the 20t ring. You might need to modify the cage. I think Abundant Adventures used to have instructions for how to do this on the website, but I'm not sure if that's still the case. In any event, I'd love to know if you make it work and, if so, how.

I_like_cereal

Can I ask why? I suppose if you were doing the Triple Bypass in Colorado maybe.

Why not get a Sram Rival compact with an 11/32 or just put a mountain bike triple and associated front and rear ds on the bike..

Just askin.

Medic Zero

Thanks! I'll update the thread as I experiment with it.

Medic Zero

I'm already running 53-42-32 on a mountain triple and either an 11-32 or 11-34 9 speed on the rear (can't recall which at the moment). I use the bike for my daily commute which has long descents that I like to keep spinning on (run out of resistance), and I also use the same bike for 3-5 day bike camping trips fully loaded with tent, sleeping bag, water, food, etc. Most of the places I wish to do my trips are at least moderately hilly and some very much so. I'm quite concerned that 32 isn't a low enough gear to actually be able to climb these hills when fully loaded for touring. I live in an apartment and so have limited room to have more bikes to have different ones for different tasks, although I have managed to shoehorn a back-up bike into my small storage space that came with the apartment, it'll be months before I can afford to build it up to suit me.

I'm not familiar with the Triple Bypass, but I live in Seattle which is quite hilly, will be doing most of my trips in Western Washington state which is quite hilly, and also in parts of Northern California that are vary all the way to downright mountainous as well. I like to go fast, and also need to be able to be a loaded mountain mule.

fietsbob

20 years ago I tried one out, used the same XT FD ,
pushed the crank further out on a longer spindle
to make room for #4..

Now I know, a recumbent trike is the application ,
as the low can be so low, that you will fall over if trying to start
on a hill again.


none are available , now..
Offers for mine? a 16t. I'll throw in a dished 26t stainless 74 bcd..

Drew Eckhardt 

Horrible spacing between gears, low that's far short of the 34x48 equivalent you'd get with 20x28.

fietsbob

I run a Schlumpf Mountain drive crank on my Brompton, now,
a 54t for the small wheels , low is the equivalent of a 21.6t chainring.
15t hub cog
18" low.. 6 speeds, the 3 gears in the hub get used twice, and I can shift both at a stand still
as they are both planetary gears.

2_i 

For me, the derailleurs that have, so far, survived everything I threw on them are Shimano FD-M900 and FD-M901. (I have by now fished out enough many of them out of Ebay, to afford revealing this type of secrets.) Below you can see an arrangement to take care of the chain slack when using a small cog-small ring combination. Otherwise, there is a page of Michel Gagnon on Tamer Quad.

Medic Zero

Thanks for confirming what I was thinking about that!

Medic Zero

Thanks SO much for that info!