Front Derailer on a Beast

[blown240]

First post here, but I've been lurking for a while. Ive been into bikes my whole life and have been working on them for 20 years since I got my first job at a bike shop when I was 15.

My buddy just ordered his beast, and I hope to order one soon. We both have high end mountain bikes, but the Beast just looks like so much fun.

I have read a ton about these bikes and I havent seen anyone try to put multiple chainrings on one. Granted a rear cassette would probably be better, but it seems the 170mm rear width would make this rather difficult to do.

My thoughts are to use a 2 or 3 ring setup, and then add a rear derailer as a chain tensioner. Even a 20/32 double would be great. This would give a climbing gear for those who would want to trail ride. Maybe even team this up with a 3 speed, or even a 7 speed rear hub. This may even work with the wider, cruiser style, chain that I assume the beast comes with, but I am not 100% sure on that one.

Thoughts?

 

[Wildcat]

Welcome aboard!

I put a set of basic chain rings on mine, from a cheap walmart mtb. I planned on manually changing gears on the chain rings by hand, using a rear derailler to take up the slack. Until I figured out how to mount a front shifter. I wanted to use the coaster brakes that came with it, but the slack in the chain makes that impossible. You'll have to use handbrakes if you want multiple chain rings. I wound up using only the middle ring, 32 teeth and that gave a better ratio than the 36 it came with. Lastly, these bikes may not be able to handle all the torque from a lower gear, and you'll need to lube and adjust every bearing on the bike when you first get it.

 

[HRJG]

I put a front derailleur on my Beast, with a rear derailleur as a chain tensioner. I have a link to a detailed blog post about the build in my "The Beast Is Loose In Denver" thread, if you want to check it out. The current configuration is a bit ugly, but it works. I am working on making look a bit nicer.

 

[blown240]

Thanks for the replys!

I definatly plan on running some sort of hand brakes. Probably Canti, but maybe a front disc. I also want to attempt some sort of rear suspension, but that will be a long ways off.

HRJG - I read your posts on the front derailer. About how far out does your pipe mount stick? It looks like about an inch. I am thinking maybe some sort of aluminum block that has a clamp on one side and is threaded for a braze on style derailer. Just a thought...

I really hope to get the $$$ together soon to get one. I have 5 or 6 bikes right now, so maybe its time to thin the heard, get some cash, and get a beast!

 

[blown240]

A derailer like this may be the ticket!

http://www.jensonusa.com/Front-Deraille ... Derailleur

 

[HRJG]

The tube that the derailleur mounts to is 1-1/8", I believe. I tried an e-type derailleur, like the one you linked to. It took up enough space behind the fixed cup of the bottom bracket that the adjustable cup ended up threaded almost all of the way into the frame, when it was adjusted. That didn't leave enough thread for the lockring to be secured. Those derailleurs really only work well with a cartridge bb.

Plus, the swing was not sufficient to reach the outer chanring. I have a braze-on type derailleur on the way, and I hope to get it installed in a nicer-looking way.

 

[Tater]

I made this proof-of-concept offset derailleur mount using a 31.8mm handlebar stem. I'm using a band type Suntour Cyclone derailleur. You ought to be able to easily mod a stem to hold that direct mount derailleur you have coming.

 

[ifitsfreeitsforme]

Tater that is sweet.

 

[Tater]

Tater that is sweet.

Thanks.

I should also add that you can do a three or five speed rear cluster using a Choppers.us wide rear hub. You will need to thread a slightly longer axle and spread the stays a little.

Obviously not a beast, but the same process applies.

 

[HRJG]

Tater: Sweet front derailleur mount. I believe I will probably go that route. I ordered a 3-speed freewheel, last week, for my Choppers US hub...

Looks like we think along parallel lines.

 

[Tater]

With the three speed cluster, you may not need to make a longer axle. Post some updates when you get it together.

 

[HRJG]

Will do. I am also building a bike for a friend which may end up with a 2-speed freewheel, on the same hub.

 

[alecw35]

I just had a quick look thru ebay at various front derailleurs. heres a Sunrace mech that's got a band fitting, similar to old racing bike brake levers. Maybe the same as that Suntour mech. But a new product so should be easier to find. Should be easy enough to make a band that suits.

http://www.ebay.co.uk/itm/SUNRACE-MTB-S ... 58a158525a

As for fitting an E mount front mech. They might be tricky to fit with a regular cup type bb. As the spanner might drag it round with the cup.

I have narrowed old Raleigh bottom brackets. On RSW and Twenty models. As they are about 75mm wide. I recut the threads, as they are slightly different pitch than usuall. Then cut a sliver of the BB shell on both sides, and filed it so the faces are straight and smooth. To the 68mm wide that modern BBs usually are. I know you can get 73mm cartridges. But I didn't have one at the time.

Anyway. You could retap the Mongoose BB, probably needs it. So the threads are clean and far into the shell. Then cut a sliver off each side, so that theres enough room for the Emount mech and the BB cups to sit in properly with the lockring on there. If you decide to remove the emount mech. You can fit Strumley archer cog spacers under the BB cups, to take up the space again

 

[HRJG]

If I ever do go with an E-Type derailleur, I will just use the Tommisea cartidge bb. It works in the frame, and has the ability to run with the derailluer mount behind it. But, the derailleur which is on there is working just fine, at this point, so I won't fix it until it's broke (as they say).

I cut a Raleigh 20 bb shell down to a 73mm width, once, then retapped it for a Japanese bb. Worked like a charm.