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GT Avalanche mountain bike conversion suggestions

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    GT Avalanche mountain bike conversion suggestions

    I purchased a new GT Avalanche 29" mountain bike with a 21" frame for my tall guy size. My original plan of using a donor fat tire bike with Bafang BBSHD motor and battery fell through due to incompatibility (120mm motor). I am totally new to this and am looking for the best matching of components. I am planning on buying from Luna for reliability reasons unless others have better suggestions (ie more affordable and still reliable).

    My current take is to buy the BBSHD and a 52V 21ah battery (bigger is better?) for off-road mountain trail riding. My bike has hydraulic disc brakes and I would like to get a brake cut-off for it but am not sure what is needed. The biggest complaint with the bike as is from what I have read is the chain snaps during normal riding, so I will have to upgrade to a stronger chain and possibly sprockets as well. Any and all suggestions are welcome!

    #2
    I did not look close at the Avalanche's last time I was in a store, I was looking at the Aggressor because that was the one in my friends price range but at at a glance it looked like a decent bike. I don't remember if I looked at the bottom bracket area thinking about clearance for a BBSHD or not. The 3x drive and not especially fat tires are usually good signs as far as fitting a kit.

    For brake cut outs order the hydraulic option. The sensors are a small rectangle that comes with 2 sided tape. You stick that on the lever body somewhere. The other part is a magnet which is a small round thing in the kits. The magnet attaches to the lever usually with a zip tie. Put a mark on the magnet and try different orientations some are more sensitive and responsive than other directions so having the mark is important so you know where its at when it works best. I have had good luck with hot glue for attaching them. You can kinda build that up if it needs to go on an uneven surface. Its also nice that you can just heat it up and get the parts and glue off again if you want or need to. I was able to mount mine on the bottom of my levers so they are barely visible and would take quite a hard hit to knock them off.

    I like a gear sensor especially if you are already worried about breaking chains. Other than the $50 it can't hurt.

    Unless you can find some details from someone that has already done it I would not order a upgrade chain ring right away. That having a triple on it now should have room for the stock 46t and you can see what that gives you for a chain line and clearance and how it feels gear wise. Most of the time you will need as much offset as you can get which is 40t or bigger. The 40t comes from Lekkie and is very expensive because it includes a new gear case cover for added clearance. The Lekkie 40t and Luna Eclipse 42 have the most offset you can get but not all frames have the room for them. The Eclipse is fixed and the Lekkie 40 has some sort of spacer that can give you 3 different offsets. Lekkie also makes a 42 that has 1 mm more offset than the stock 46 where the Eclipse has I think 6mm more. Its great if you have the room for it but not all frames do. If your frame doesn't have that much space then I think the Lekkie 42 is a better option over the Eclipse with a bunch of spacers stacked up.

    Offroad the Luna Wolf family is good because they are fully potted which makes them about as vibration resistant as possible. Potting is where they basically pour an epoxy into the case to really hold and seal everything up. Most other designs use a web like holder and hot glue then cover it all in shrink tube to hold it all in place. That works great on your desk and maybe isn't bad with just minor vibrations on the street but hard banging on the trails I like the idea that everything is super solid. Another thing you get with a Wolf battery is the magnetic mounting system. Many people forget about mounting and protection when shopping for batteries, the wolves have both included. They still need some backup like a strap for if you go down sideways or like me I punched holes in their triangle bag then put the magnet in the bag. Adds a little stealth with backup protection.

    Battery size wise I would use 2 miles per amp hour as a very wide ballpark number. The regular Wolf at 12 ah should get you 24 miles, the 13.9 28 miles. You run it from 100% to 0% maybe more. You ride slower on flat ground with pedaling some you may get 3 or even in some ideal cases 4 miles per amp hour. Some fat people on fat bikes that like to go fast can struggle to get 1 mile per amp hour. If you can afford the 21 then go for it. I have one big pack then a couple Wolves and I really do notice the difference in weight even when in the triangle. I don't use my big pack off road because I don't like the weight and its a 'soft' back with no built in mounting so I also don't like the idea of it banging around. I do use the big pack on my street bike since that tends to go further and doesn't get banged around like my trail bike does.

    Before forget one downside to the Wolf family and their fully potted design is there is pretty much no fixing them if something does go wrong. Luna does stand behind them when they are new so if there is some sort of defect that happens out of the box they will take care of it but when you get down the road there is pretty much no fixing them. Soft packs and the shark style can be opened up by someone that knows what they are doing and there is a chance for repair. The flip side to that is making the pack more open could be why it failed in the first place and needed repair where the potted Wolf may have survived what rattled or got the other one wet so who knows.....

    You should do some research on displays. Really there are 3 choices. The big ones that go in the center and have remote controls.... free one that comes with the kit or take the upgrade to something like the 860c. If you like to have your phone for maps or whatever this takes up the best place to mount a phone but they also tend to have usb jacks you can use to charge a phone or GPS so long rides maybe that's important? 500c mini. I have 2 of those and really like them. Buttons built in and big enough to see what you need to see. No USB. No clock but do take up a decent chunk of space on the bar so depending on what else you want to mount could be a consideration. Last option is the Eggrider. Most expensive but most compact and I think the only one that will do blue tooth to your phone for more advanced settings and logging.

    I'm a big guy with minimal skills and abilities and I just got back from badly abusing my bike on some green and blue trails. My trail bike has a SunRace 11-42 cassette on and a 42 Lekkie up front. I'm running a hyperglide chain that I paid $20 for on sale, I think regular price is $40 so not anything too special. So far its holding fine and has got my fat ass up some decent rock covered climbs. I do have a gear sensor and try to make sure I am shifted before I get into the climb, I will often error on the side of too low a gear just so I don't have to shift during the climb.

    I would also recommend getting the install helper kit from Luna. You may not need anything from it but its nice to have and not need rather than be stuck waiting for it and paying almost its value in shipping on its own to get later. Any of that stuff you order when you order the main kit you get a discount on so its worth doing all at the same time if they have it all in stock.

    For a charger if you go with the Luna stuff I do like the advanced charger. I like having the meter on it so I have some idea what the status is. I also like that its got the % selector and rate selector. 80% and 1 amps is said to be best for battery life but sometimes you do need to go to 100% to make sure the cells stay balanced. There are also times when your friend calls late for a ride and you want to jam as much charge in as fast as you can so its nice to have the option to kick it up to 5 amps.

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      #3
      Thanks again, 73Eldo! Very informative info. I always find myself in with the mindset of "for just a few dollars more..." when it comes to increasing battery range. Luna is out of several parts and batteries such as the DireWolf, so I will have to wait to order those items. Looking forward to getting everything rolling!

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