Does anyone here have any experience with Polygon bikes? They seem to be a decent entry level option for the money. I’m considering using a 2021 Polygon Xtrada 6 1x11 hardtail as the base for my winter project/ first e-bike build. I’ve been doing a lot of research and it doesn’t look like a terribly complex project.

Why? It is a good looking bike that has decent components and a lifetime frame guarantee. The seat stays are kinda thin but the chain stays are nice and meaty. I thought about using my old steel frame Schwinn mountain bike but it’s brakes are terrible.



Im about to order a kit similar to this but with an upgraded rim. I’m leaning towards a rear wheel drive 48V 1500W kit.

Looks like a nice frame. My suggestion is to make sure it is STEEL and not aluminum and to make sure to use some kind of reinforcement on the dropouts. 1500watts is strong enough to twist a weak frame. God Bless

It will definitely need a torque arm installed to help spread the stress from the electric motor. Something similar to this.





That frame is T6 and the chain stays are pretty thick so it should be ok with a good torque arm....hopefully. I’ve seen similar builds that use aluminum hard tail Trek bikes. I really want to avoid a steel frame bike if possible.

I’m not trying to build some high speed machine but rather a bike with enough grunt that it can handle hills and light trail riding.

quote:

Originally posted by stickman428:
a lifetime frame guarantee.

It has a lifetime guarantee until you convert it to an e-bike, then all warranties are null and void.

hmm, wife would like an e-bike, she has a bike already, where'/what's a good place to start on learning the conversion process, motors, batteries, install issues, I'd like to find a bolt on product and have a nice project..

HRK, These two videos are a good place to start.




Link to original video: https://youtu.be/KlAocXpyXvc




Link to original video: https://youtu.be/GyXlYrZu8-A

Thanks, I"ll check them out...

She just needs something to ride in the PUD area, local roads, 35 mph max limit, parks, 7/11 no real trail riding.

Does modifing the bike to make a e-bike possibly void the lifetime frame warranty. .......................... drill sgt.

quote:

Originally posted by drill sgt:
Does modifing the bike to make a e-bike possibly void the lifetime frame warranty. .......................... drill sgt.

Almost all I bet, yes.

Without capable bike experience, it is usually a better idea to buy an e-bike complete. The attachment points/braise-ons can be built with frame, strengthened where it counts, ect.

The other important points are to consider the serviceability of what you buy, and the insane patchwork of local laws. For example, Fort Meyers Beach has banned e-bikes, and FL state law says you must have a pedal-assist not a throttle only bike. Hardly any local LE bothers you about the 3 classes of e-bikes, since it has been confusing and they have better things to do. Never know what the future holds tho.

Dirty little secret of e-bikes is what new batteries will cost you in 3-5 years.

Yeah, I’m guessing adding a electric motor to the bike probably voids it’s warranty. It’s not really something I’m too worried about. If I did crack a frame due to my modifications I wouldn’t trouble the manufacturer about their warranty, I’d just source a new frame. There are plenty of aluminum frame bikes out there running 48V 1500W motors and they seem to be holding up just fine. As far as the frame goes I shouldn’t be anywhere near it’s weight limit and I am going to take time to make sure the torque is dealt with properly.

Buying one complete takes all the fun out of it. Building one from a kit is half the fun. It’s MUCH more cost effective to convert a bike to electric than to just buy an e-bike. If I used my trusty old steel frame Schwinn mtn bike as a base to cut cost to the maximum I could build a decent e-bike for about $1000-1500 total.

I thought about using my old GT Karakoram 29er for a base because it’s built like a damn tank but it’s frame is too big for me and I’m probably better off just selling it to help offset some of the cost of the project. It’s frame is an XL and I’m more suited to a medium or large frame bike.

I just purchased a high end triathlon bike. Under my own power, doing 30mph on a flat road takes considerable concentration and the bike is built for speed. On a few local downhill stretches, I'm hitting 45-50mph in the tuck position and the pucker factor is almost there.

I'd be concerned about an occasional bike rider jumping on a traditional MTB outfitted with an e-bike power setup. If someone is used to putzing around 5-10 mph under their own power and those steering/braking dynamics, jumping up to 20-35 mph could surprise them to the point of losing control. Kinda like me slamming a BBC in my little Civic. It's gonna drive much differently.

That being said, I'm totally on board with this DIY project. Do you have to upgrade tires or brakes?

quote:

Originally posted by Russ59:
I just purchased a high end triathlon bike. Under my own power, doing 30mph on a flat road takes considerable concentration and the bike is built for speed. On a few local downhill stretches, I'm hitting 45-50mph in the tuck position and the pucker factor is almost there.

I'd be concerned about an occasional bike rider jumping on a traditional MTB outfitted with an e-bike power setup. If someone is used to putzing around 5-10 mph under their own power and those steering/braking dynamics, jumping up to 20-35 mph could surprise them to the point of losing control. Kinda like me slamming a BBC in my little Civic. It's gonna drive much differently.

That being said, I'm totally on board with this DIY project. Do you have to upgrade tires or brakes?

E-bikes that are "street legal" as bicycles without (technically, at least) needing a motorcycle endorsement on the rider's driver's license are limited to either 20 or 28 mph depending on the class of the bike. You can pedal the bike faster than that, but the motor won't help you do it.

I have a 28mph-class pedal-assist E-bike that is built like a heavy-duty hardtail mountain bike, it is perfectly comfortable to ride at 28mph (although it does require significant pedaling effort to get there).

Broadly speaking, there are two main ways E-bikes are built, they can have a motor in the rear wheel hub that helps turn the wheel (hub drive) or a motor in/on the frame that helps turn the cranks (mid drive). Hub drive motors are not impacted at all by the bike's gearing, while mid drive motors are.

I'm pretty convinced that mid drive E-bikes ride more like "analog" bikes and let you get the most out of the motor (because shifting gears affects the motor, too), but a DIY mid drive conversion, while technically possible, is complicated to the point of infeasibility for almost anyone. Also, they require beefy chains, chainrings, and cassettes, because the additional torque of the motor can shred wimpy ones.

On the subject of tires and brakes, competitive downhill mountain bikers go insanely fast and are incredibly punishing on both tires and brakes. If you aren't building a literal electric motorcycle, I would be very surprised if any reasonable E-bike could put out more than the heavier-duty end of mountain bike components can handle.

Some bike tire manufacturers do note tires that are recommended or not recommended for E-bike use, and some manufacturers certify certain tires for E-bike use under European regulations (apparently, in Europe, fast E-bikes are legally required to use certified tires). One example I am familiar with is Schwalbe tires, a German manufacturer of excellent bike tires - their tires that are labeled "E-50" are certified under the European ECE-R75 regulation for use on E-bikes that go up to 50 kph (31 mph).

The kit I’m going to get has upgraded tires and rims. I’m going to wait to assess the brakes since they might be fine. The kit I am getting apparently has regenerative braking so it’ll be interesting to see if that feature actually makes much of a difference and how well it works. I live in an area with rolling hills and a few long down hill areas I like to ride so I’m quite curious to see how it performs.

According to my phone gps I hit 25.7 mph on my Giant Anthem X-29. Riding a full suspension bike with a slight front wheel wobble (very minor) at that speed actually feels much faster than you would think. If I can build a bike that can go 35-40 mph and has a good bit of range then I’ll consider it a success.

While I could hook up the pedal assist with the kit I’m getting I think I’m just going to wire it up as a straight thumb throttle or possibly a twist throttle to engage the electric motor.

I went ahead and pulled the trigger on the Polygon Xtrada 6 1x11. Here we go.

I thought the warranty on the Polygon frames was only 5 or 10 years. No matter - if you modify it you’re going to void the warranty. Polygon alloy frames are just as good as 95% of the other frames out there. They just make their frames in Indonesia, rather than sourcing frames from China or Taiwan like all of the major U.S. bike brands. Polygon is a direct-to-consumer business. You won’t find a better price/deal on similarly specced bikes. You’re trading support of a local bike shop and customer service for that lower price.

The brakes and Deore drivetrain are fine (for a non-electric bike, anyway). For your project, I would want to up those rotors to 180 or 203mm for a little more stopping power.

quote:

Originally posted by stickman428:
It will definitely need a torque arm installed to help spread the stress from the electric motor. Something similar to this.

Kinda looks like the coaster brake I had on my first bike a good long time ago.

My first impression of Polygon is pretty good. More to come tomorrow.

quote:

Originally posted by preten2b:
Dirty little secret of e-bikes is what new batteries will cost you in 3-5 years.

What is the cost typically?
Do the batteries only need replacement on the converted bikes?
Do OEM e-bikes have the same type of battery life?
Are the batteries common across all bike brands or are some proprietary?

quote:

Originally posted by JoseyWales2:

quote:

Originally posted by preten2b:
Dirty little secret of e-bikes is what new batteries will cost you in 3-5 years.

What is the cost typically?
Do the batteries only need replacement on the converted bikes?
Do OEM e-bikes have the same type of battery life?
Are the batteries common across all bike brands or are some proprietary?

Perhaps $200, perhaps $800. There is no typical, each bike brand can be different. Frame mount/ proprietary, rack mount, power and range vary as much as the prices of firearms. Point is to know what your choice will cost you in a few years and how to take better care as to get the maximum life.