Best bike frame for ~55kmh

Hi. New here, so warm greetings to everyone. I wonder what kind of frame is best to build my ebike conversion around.

I like to ride my trek bike at full speed, sustain around 30km/h for my flat ground commute. Reason I would like to convert bike to ebike is I would still like to padal at full power (I am fit guy, never tested but I guess I sustain 150/200w), but go even faster to keep up with trafic. Mostly its 50km/h limit here, so If I could sustain 50km/h maybe be able to go 55 when really needed that would be perfect.

Mostly I see people recommend full suspension bikes, but I really dont see the reasoning behind that. Arent road bikes, bikes made for high speeds on the road.
On the other hand I am a tall/heavy guy, so dont really see to much reason trying to scale down the weight as much as possible etc. 5kgs on 90kgs me + battery motor etc cant really matter that much.

But I recon it is still important to have an agressive stance while biking.

In conclusion I wonder what are some good frames to build ebike around, where you pedal at max, and have ekit help give you that extra 200/300w power

I reckon something like this, but is there anyway to buy only frame like this, or even better have a frame made to fit most middrive systems

Do you want to convert the Trek you already have or buy an extra bike?

The bike I have is kinda small, its a tiny bit to small for me as a regular bike, and if I was to go faster, would prefer to have bigger bike.

So I am looking for frame to start anew. Also have 0 welding expierience, so even modifying a frame is out of question for now

Also let me just add that laws limiting ebikes to 45km/h are so dumb. I remember owning gas moped as kid that was also limited at 45km/h and with roads limited to 50kmh, most people drive cars 50-60kmh next to you. And with moped/bike limited to 45 you are just below that, and then you never know whether to take one full lane, or try to squeeze to te side, with people overtaking you in your own lane. Its just a mess

If you're a big guy, try out some 29ers. I still think they're the best for all terrain and fast road bike feel (eg. gravel bike on roids for 1/2 the price). They combine MTB robustness with road bike speed/feel. (I'm biased as all my ebikes are based 29ers and all do 55km/h).

You need about 1-1.5kw to cruise at 50km/h on power depending on your front profile/aero. 300w wont cut it as wind is a bitch.

My 29er Cyclocross/Gravel build with a BBS02 in road/stealth mode to hunt down roadies :

My take on full suspension was that it was not so much needed for the road, if you take the lane where the surfaces are better. Most potholes can be avoided, or routes changed to better streets to ride on. But you need to be very aware. Once I hit a bump on a tall manhole cover, and was on just the front wheel going 45 mph. That was tricky!

But when you need to go off road for your life, well, in the ditch on a road bike at 45 kph is not going to work so great. The full suspension shows its value when you get caught out, or just want to take a dirt short cut. ( or maybe fun cut) If you need to do curb hopping to get to that safer route, then FS is priceless.

If you ride bike lanes, well, you might like FS just to ride over the crap you find there, 2x4's, chunks of tires, and of course, when do they ever fix potholes on the edge of the road. Some shoulders are rougher than dirt roads.

It's not so much as the frame, but the tires and wheels and tires you have. I've had my bike to 100 kph airborne.

I would take dogman dan's advice, at that speed I would go with a mountain bike with full suspension, with tires in the 190 range or more. Sometimes you cannot plan your route to avoid trouble, also if you travel when it is gets dark things can happen real fast. Hitting a bump at that speed can send you flying. Down side is full suspension bikes are a bit heavier. Having been E-biking for more than a few years, I would go with a full suspension mountain bike frame.

I did not say nothing but FS for street. I ride up to 33 mph on this bike, no suspension. But I don't curb hop it, or take the fun cut through the dirt lot behind the store, and try like hell to see the 2x4 in time to dodge it.


Because this bike is long and heavy in the rear, it does not stand on the front wheel if I run over a tall manhole cover.

The wheels are sturdy, the rear motor wheel a very good build, and the front wheel from a high quality mtb.

BUT,,, I never ride this bike 30 mph in the dark, where you will get surprised by potholes, debris, and even speed bumps in parking lots.

What you will need will depend on where you ride, and when, and how fast.

I am 6'8" 225 lbs, I love my 29er. Its a Trek X-Caliber hardtail, the biggest frame size it comes in. I dont mind taking it on rough ground, but if its bad I end up standing for most of it. Longing for a suspension seat post....

At your height, I sure bet a large frame 29er is fitting you a lot better.

Generalizing quite a bit, the one thing that makes a bike frame suck balls for higher speeds than 20-25 mph, is when it is floppy from side to side. This is one of the reasons some folks stick to the steel frames, and quite heavy ones at that. For some, nothing can beat an old school chromoly frame.

If the frame has enough lateral stiffness to not go into the wobbles at 30-40 mph, its suitable for a speed e bike. Any very good bike tends to meet this test, and very few of the affordable bike shaped objects at Walmart do, unless they are steel.

So generalizing too much,, a bike costing above $500 at the store will tend to do fine, up to about 40 mph. The frame is usually a bit thicker, or in some way stronger, tube than the really cheap bikes, and often they have a disc brake, which some will prefer for stopping at higher speeds.

If you ride at low speed, and try to start a wobble with the handlebars, a weak bike will visibly bend between the pedals and the head set. If you see a half inch of flex, you aint going to be happy at speed on that bike.

29" wheels on a hub motor is not a good choice.

Interesting question raised and interesting answers provided...

I'm posting primarily because I noticed your interest in pedalling and not just having a glorified moped and want to point out the TSDZ2 as a choice. It's a mid-drive, will fit most bike frames, and it has a rare feature in that it has no throttle and is ONLY an assist-system. It has a torque sensor and when you pedal, depending on setting, the motor adds a factor to what you provide. At the lowest setting, "eco", it gives you about 1/3 more torque than you yourself provide. At the next setting, "tourist", it gives you 100% more, doubling the total energy (you and it each doing 50%). The next mode, "fast", gives 200% more torque and the highest setting is documented to give a factor of about 3.68, as I recall. ... There's no throttle, you have to pedal, but then it gives the most classic bicycle behavior. There's no need for brake cut-out switches or anything like that.

There's a thread here on this site dedicated to the TSDZ2. Find it here:

https://endless-sphere.com/forums/viewtopic.php?f=28&t=79788&p=1302532#p1302532

I also want to add a little to the other bits of discussion brought up here. I intentionally set up my system for high speed within the known characteristics of the TSDZ2. It should do a little over 34 MPH - about 54.4 KPH, pretty much your target - by matching it with a 52T chainring and a 11T rear gear. I'd prove the point if I could find a stretch of road that was smooth, long, and empty enough to get up there! Oh, and I've got a bit of a problem with my 11T - chain keeps trying to hop out of engagement, but I can get up to 29MPH with my next gear down, a 13T. ... Whoever said it upthread is right; the wind resistance gets to be significant over about 20, and the faster you go the worse it is. (However, I don't agree with them on the number of watts they call for, at least, that wouldn't be required with the TSDZ2 since the rider has to be pedaling hard for the unit to be working hard! (My unit is a 48V, 15A unit which is officially rated at only 500W but it's really more like 720W - recall that watts are amps times volts. And, we hear there's a new 18A newly available.)

I created a gear selection chart you can use - find it here:

https://endless-sphere.com/forums/viewtopic.php?f=2&t=88719&p=1301788#p1301788

Like you, I'm very interested in speed, but not very interested in the various suspensions (beyond tires themselves), but I DO agree that they could save your butt in some circumstances. For example, I lost a rear wheel two Saturdays ago when forced onto a railroad-rail filled bomb crater they call potholes here in Oakland which I might not have lost... A little more "pneumatic suspension" in the way of more air in the tires (volume, not pressure), would be nice so long as it's not overboard. My bikes old-school brakes haven't been an issue so far - they wear out hella-fast but also stop reasonably (on my AL rims) but then I am adapting in some Kool-Stop pads - they should arrive tomorrow and I'll promptly install them. However, I also see the wisdom of disks on something this fast.

My bike is an old Raleigh copy known as a Legran. It's a pretty darned faithful copy, especially regarding the frame. It's got 27" wheels - which is problematic - and is a bit heavy, but then, it's strong as hell. You don't mention it but I'm keen on replacing a car - REALLY replacing a car - and so some "cargo" capacity is a must. So, I added in some serious capability and the strong frame makes me feel a lot more confident in it. You can read up about it and my electrification effort here - I give pricing and all sorts of specifics:

https://endless-sphere.com/forums/viewtopic.php?f=3&t=88943&p=1303431#p1303431

If I had it to do over again, and I might do it over again when budget permits, I'd go with a younger version of the same basic frame, probably in steel because, as you point out, the weight isn't an issue to have a panic about and durability is definitely important. And I'd probably pick something that could take disks.

Do let us know what you choose! And, start a thread for your bike's build!