How important is the donor bike?

[drod]

Hi, The background is that I have an old GT Avalanche 1.0 that I've had since new - probably about 2007. I'm looking to convert it to an ebike. The usage will be pretty limited as I use it on flat roads at home now and again, but take it on the back of a motorhome for country roads, off-road and cinder tracks etc.

I notice that some of the conversion costs - for example, mid drive kits with battery etc - can build up and I'm wondering if my bike is too old to use as a base. Should I swap the bike first, then add a kit? The bike itself is more than adequate for my needs, so I'd be just upgrading for the sake of it but don't want to waste money adding a kit to something thats too old. Is there a 'rule' of something like 20% bike cost and 80% kit cost? Thanks.

 

[d8veh]

Hi, The background is that I have an old GT Avalanche 1.0 that I've had since new - probably about 2007. I'm looking to convert it to an ebike. The usage will be pretty limited as I use it on flat roads at home now and again, but take it on the back of a motorhome for country roads, off-road and cinder tracks etc.

I notice that some of the conversion costs - for example, mid drive kits with battery etc - can build up and I'm wondering if my bike is too old to use as a base. Should I swap the bike first, then add a kit? The bike itself is more than adequate for my needs, so I'd be just upgrading for the sake of it but don't want to waste money adding a kit to something thats too old. Is there a 'rule' of something like 20% bike cost and 80% kit cost? Thanks.

What's important is how and where you can fit a battery. Disc brakes are more or less essential and cable ones can be upgraded to hydraulic as part of the conversion. If you want to fit a mid motor, the shape of the frame around the BB is important to make sure that the motor can fit. Full suspension frames can be a bit more tricky for a mid motor because you need to find a way to anchor the motor to stop it rotating around the BB due to torque reaction. GT Avalanche 3 looks like a pretty good donor to me, but it depends what you're trying to achieve. It'll be fine at an average speed of 20 mph, but if you want 50 mph, you need something else.

 

[marty]

Also important that the bike fits the rider.

Disc brakes are more or less essential and cable ones can be upgraded to hydraulic as part of the conversion.

Cable operated disk or caliper brakes are fine for a bicycle. Hydraulic is for motorcycles. If the brakes that came with the bike stop OK? Leave em alone.

 

[fill]

As said above BRAKES- rim brakes are not upto the job of providing you with a safe reasonable stopping distance especially when you start moving faster than your average analogue cyclist.

Secondly is the bike comfortable, chances are you will spend more time in the saddle than out of it with assistance and as a consequence be prepared to feel every bump in the rd without some suspension

 

[drod]

Thanks All. The Avalanche 1.0 was was a pretty good bike at the time - it has hydraulic disc brakes. I'd not thought about the issues with speed too much, but thanks for the heads up.

 

[2old]

There's nothing wrong with that bike for conversion. This is an older Specialized Stumpjumper which works fine for errands, but would need a suspension fork for MTB (but not smooth dirt roads). Note the linear brakes which function adequately for me.

 

[E-HP]

but don't want to waste money adding a kit to something thats too old. Is there a 'rule' of something like 20% bike cost and 80% kit cost?

There's nothing about a kit that precludes you from moving it from one bike to another, so its won't be a waste of money if you want to switch things up later. I started with a 90's vintage straight tube rigid chromoly frame, and moved things over, both bike and ebike components (no cost for the bike, $650 or so for the kit, battery and misc parts), to a better frame I found on Craigslist 6 months later. The initial build was great, but I just liked the looks of the frame and the top tube made it easier to get on and off.

PS. I started out with linear pull brakes, upgraded to cable pull discs, then converted to 4 piston hydraulics. The hydraulics feel better, and stop well with very little effort, but the only time I've ever felt worried about not being able to stop is with the disc brakes when they started fading badly near the bottom of an 800 ft descent. I've never had that happen with the linear pull brakes, although I'd need to squeeze them like a death grip, but they always worked, but I also was using regen back then as well. Now that I'm building a new mid drive on my vintage full suspension bike, I'm moving back to linear pull brakes, since I'm not ready to spend a bunch of money on new wheels to convert it, until I know for sure I like the mid drive in the first place.

 

[docw009]

GT Avalanche 1,0 like this one? Looks like a nice bike to electrify. If your York location is the UK, I believe you have to watch out for law enforcement initiatives where they seize ebikes they don't like? Be careful.



How important is the donor bike? A clunky bike will still be clunky with a motor. It does cost money to upgrade the clunky parts.

It would seem obvious that if you plan to scoot along with car traffic at 20+ mph that you need good brakes. What wasn't obvious to me, averaging 12 mph and living in a locale scoured flat by glaciers that I might occasionally hit 25 mph going downhill. We took our rim brake bikes to Colorado a while back, and had some long downhill stretches. They still did OK.

 

[fill]

If in the UK the circa £400 all inclusive yose-power kits are good vfm. search for discount codes too. The batteries are respected enough to be a top choice for generic hailong/silverfish replacements.. and the kit is inclusive of tools needed for the job, If needed email support is responsive ( time zone differences apply) and quick to replace anything identified as faulty

The down side is the control system will be locked to apply with the UK/EU regs, but if thats an issue a swap out of the control system with a £50-£100 replacement system (controller/display) is plug n play mostly.
And the controller is a basic speed limiting type, so pas1,2,3,4,5 are simply denoted by speed caps, circa 4mph, 6 mph. 10 mph. 13 mph 15.5 mph. - again a controller swap out can fix this with the KT controllers offering a configurable proportional power output system.


fwiw ive been content with my stock yose conversion for a couple of trouble free years now.
The controller 'limitations' ive overcome with a nominally loose back brake lever i can crack and activate the brake cut off without employing the brakes. This provides a simple and intuitive 'virtual clutch' for fine motor control.
And my bike is NOT built for speed, so the 15.5 mph cap isnt an issue as local road and traffic conditions prohibit speeds in excess of that anyway. However considering the acceleration when the motor cuts out at 15 mph, if uncapped and supplied with a few more amps greater speeds are well within its range.

EDIT^ One other feature of the yose kits is they are very generous with cable lengths so the final cable management task of the conversion even on a bike the size of mine is more about hiding and stashing bundles of flex.

 

[Chalo]

As said above BRAKES- rim brakes are not upto the job of providing you with a safe reasonable stopping distance especially when you start moving faster than your average analogue cyclist.

This is absolute hogwash.

Rim brakes can be much stronger than disc brakes. They have a much, much bigger rotor for one thing. They also have a larger variety of more proven mechanisms. If you personally can't set up a rim brake worth a damn, that's a you problem. But it's not a shortcoming of rim brakes.

Here's a rim brake I made that snickers at how pitiful your discs are.

 

[bengxe]

So what you're saying is that your original rim brake and fork crowns were so flimsy you had to make your own? I'm not sure that supports the point you were trying to make. I've put shimano hydraulic discs on the last dozen bikes I've built and I can't remember the last time I had to think about them post install. I don't know which disc brake hurt you, but some modern stuff just works better.

 

[Chalo]

So what you're saying is that your original rim brake and fork crowns were so flimsy you had to make your own?

No, I bent the original forks by using ordinary cantilever brakes, so I upgraded both the fork and the brake. But you wouldn't know about such things if you're impressed by discs. Most of them couldn't bend a fork on a bet.

I'm not sure that supports the point you were trying to make. I've put shimano hydraulic discs on the last dozen bikes I've built and I can't remember the last time I had to think about them post install. I don't know which disc brake hurt you, but some modern stuff just works better.

I work on bikes every day, and I beg to differ. Disc brakes made bikes heavier, wheels weaker, and the whole system overall less standardized and less reliable than before, but they didn't give us any more braking power in the deal.

Discs make sense for big tires, and for changing wheel sizes. But they don't offer any more braking power than rim brakes, and less than most. Fortunately for most riders, they can't use extreme braking power anyway.

 

[bengxe]

No, I bent the original forks by using ordinary cantilever brakes, so I upgraded both the fork and the brake. But you wouldn't know about such things if you're impressed by discs. Most of them couldn't bend a fork on a bet.

This is a strange way of saying that modern disc forks don't bend as easily as antiquated carbon. What my brakes can do is throw me over the bars with a single finger while also being capable of running at massively higher operating temperatures than an aluminum "rotor" that's mounted on the tire. So if the lever feel were as bad as cable brakes, I'd still use hydraulics.

 

[Chalo]

This is a strange way of saying that modern disc forks don't bend as easily as antiquated carbon.

The ones that bent were chromoly box crown forks that came with the touring bike.

Earlier in the 1" mountain bike days, I went through about a fork a month until I found Bontrager "switchblade" forks that could take the strain.

What my brakes can do is throw me over the bars with a single finger

Yeah, hydraulic discs are really good at giving more braking than you want with little lever effort, which isn't a virtue in my book. But they're outdone by rim brakes at the upper end. The small rotor size and material limitations of the pads put a lower ceiling on how much power they can dissipate. If you are light enough and your bike has a short enough wheelbase, you'll never notice that. But you'll still be using lesser brakes if you use discs.

while also being capable of running at massively higher operating temperatures than an aluminum "rotor" that's mounted on the tire.

Somebody hasn't done their homework to figure out the thermal capacity of 120g of stainless steel versus 900g of aluminum (with several times as much surface area and thermal conductivity, plus much greater specific heat). If you want to burn yourself, discs are awesome. If you want to turn kinetic energy into thermal energy without burning yourself, rim brakes are better for that.

 

[bengxe]

Higher temps mean more heat shed to the air. Steel discs with metallic pads are perfectly happy running at temps that would melt rubber pads and tires. You seem to have forgotten those 2 things. Disc brakes with organic pad material or undersized rotors may be able to overheat and fade, but that's more of a setup problem. I'm old enough to remember a time before disc brakes, I won't be going back, and the entirety of the bike industry seems to agree with me. You're doing this community a disservice every time you repeat this nonsense, there are a lot of modern mountain bikes that make great e-bikes.

 

[Chalo]

Higher temps mean more heat shed to the air.

But in the case of disc rotors, it also means a whole lot less surface area in contact with air. More surface area, more airflow, more thermal mass, more conductivity, and higher specific heat all work in favor of the rim brake. On top of that, mass in the rim does two jobs instead of just one (while imposing a heavier and weaker wheel design like disc brakes do).

Steel discs with metallic pads are perfectly happy running at temps that would melt rubber pads and tires.

Yeah, they have to run that hot. Rims don't .

I'm old enough to remember a time before disc brakes, I won't be going back, and the entirety of the bike industry seems to agree with me.

The industry also agrees that your bike should be made out of plastic garbage, with electronic shifters that don't help and hydraulic brakes that don't help. They like stuff that sells for a premium, and as long as there are ever more idiots, they'll keep slinging idiot stuff to them.

 

[bengxe]

But in the case of disc rotors, it also means a whole lot less surface area in contact with air. More surface area, more airflow, more thermal mass, more conductivity, and higher specific heat all work in favor of the rim brake. On top of that, mass in the rim does two jobs instead of just one (while imposing a heavier and weaker wheel design like disc brakes do).

Except the rim is only about half exposed to airflow. A disc rotor has close to 100% of its mass within a millimeter of airflow. Its not a direct comparison. I'll never understand why you think disc wheels are weaker. Downhill bikes have used disc brakes exclusively for 25+ years, which means the strongest wheels I can buy for my bikes have always been disc specific.

The industry also agrees that your bike should be made out of plastic garbage, with electronic shifters that don't help and hydraulic brakes that don't help. They like stuff that sells for a premium, and as long as there are ever more idiots, they'll keep slinging idiot stuff to them.

I hopped off that bandwagon about 10 years ago when they started pushing bigger and bigger wheels, I agree with you on most of that. My bikes are metal, my biggest wheels are 26", and I've never even tried electronic shifting. But in my eyes, modern brakes and suspension are a safety requirement for anything with 2 wheels and a motor.

 

[99t4]

old GT Avalanche 1.0 that I've had since new - probably about 2007.

For me, that 2000 - 2010 date range is the golden range for conversion donor candidate. Frame is likely steel or aluminum, not carbon fiber, it has simple unfancy dropouts that can easily accomodate a hubmotor, is likely a 7 speed that is also compatible with a hubmotor, and has a simple uncluttered BB that can easily accomodate a mid drive.

 

[lnanek]

There's plenty of reasons someone might go with disc brakes despite them technically not having as much leverage as a v-brake. The "rotor" size for the V-brake is as large as the entire wheel, so it's simple physics that it has more capability there. And the last developed generations of v-brakes even had things like booster arches to prevent frame flex, hinged arches to keep the pads parallel to the rims by Avid, and even hydraulic V-brakes by Magura. Pain in the ass though they are, hydraulic is useful for suffering bends in the routing better than cables without making your braking worse with every foot of length and bend like cables. Especially important for internal routing.

Doesn't mean the industry might have moved on for other things, though. For example, better performance in the wet since disc brake rotors are farther from the ground than rims. Also easier wheel removal with discs without having to unhook v-brakes to drop the wheel out. And the already mentioned high compatibility with varying wheel size and large tire width. I have a dozen v-brakes in my garage, but only 2 can manage to arch around the wide tires and fenders on my tandem.

Kind of silly to argue with the physics side of things, though.

 

[drod]

If in the UK the circa £400 all inclusive yose-power kits are good vfm. search for discount codes too. The batteries are respected enough to be a top choice for generic hailong/silverfish replacements.. and the kit is inclusive of tools needed for the job, If needed email support is responsive ( time zone differences apply) and quick to replace anything identified as faulty

The down side is the control system will be locked to apply with the UK/EU regs, but if thats an issue a swap out of the control system with a £50-£100 replacement system (controller/display) is plug n play mostly.
And the controller is a basic speed limiting type, so pas1,2,3,4,5 are simply denoted by speed caps, circa 4mph, 6 mph. 10 mph. 13 mph 15.5 mph. - again a controller swap out can fix this with the KT controllers offering a configurable proportional power output system.


fwiw ive been content with my stock yose conversion for a couple of trouble free years now.
The controller 'limitations' ive overcome with a nominally loose back brake lever i can crack and activate the brake cut off without employing the brakes. This provides a simple and intuitive 'virtual clutch' for fine motor control.
And my bike is NOT built for speed, so the 15.5 mph cap isnt an issue as local road and traffic conditions prohibit speeds in excess of that anyway. However considering the acceleration when the motor cuts out at 15 mph, if uncapped and supplied with a few more amps greater speeds are well within its range.

EDIT^ One other feature of the yose kits is they are very generous with cable lengths so the final cable management task of the conversion even on a bike the size of mine is more about hiding and stashing bundles of flex.

Thanks for that - I'll take a look at those

 

[fill]

WWW.pedelec.co.uk might be worth a visit too.

 

[dgc]

drod, You need to think what you need from your e-bike build. Motor type, battery size for your intended range, if both will fit the frame, hard-tail or full suspension and how much you want to spend. There is no problem with the GT Avalanche 1.0 if it is the bike for you. When you build your e-bike make sure the wiring etc is tidy so it looks like a pro job.

For my old bones, my usual ride is full suspension, uses a TDSZ2(B) mid-drive with a 36v 10ah battery, along with a 9 speed rear cassette finished off with 180mm f / 160mm r discs brakes, range up to 30miles. Currently that motor / battery combo is just over £300. But this suits me and where I ride, a good lightweight bike which still rides like a standard bike.

As I wrote elsewhere:-
The problem for us e-bike riders here in the UK is: "an ‘e-bike gang’ of four who violently stole jewellery worth £43,000 from an individual on a London street were jailed. All four of the convicted gang members rode electric bikes to and from the scene of the crime" and also " Police in the City of London have seized more illegal e-bikes than any other force - with one capable of 70mph."

 

[JackFlorey]

No, I bent the original forks by using ordinary cantilever brakes, so I upgraded both the fork and the brake. But you wouldn't know about such things if you're impressed by discs. Most of them couldn't bend a fork on a bet.

I've seen at least two bikes in the LBS shop with bent forks; both had disc brakes. One was a road bike that the guy claimed had the fork bend during a panic stop.

(Fill said) rim brakes are not upto the job of providing you with a safe reasonable stopping distance especially when you start moving faster than your average analogue cyclist.

They don't have a problem stopping you in a safe distance PROVIDED they are designed for the task (i.e. are not WalMart calipers.)

The place that rim brakes have trouble is on long descents; they can heat the rims (and tires) to unsafe temperatures. That's why some tandems had secondary hub brakes for such descents; the additional mass could overheat the rims on the larger bike. You can still overheat discs, but the results of that are much less dramatic.

For a while all my conversions had front discs (because that was easy to do) and rear V-brakes (because most hub motors could not accept discs back then.) Seemed to work fine. I never had to go larger than 160mm for the front discs, probably because they all had regen.

 

[Papa]

FWIW. I believe quality rim brakes (on both wheels) is more than adequate for most HPV's. but I, personally, find them wanting at elevated speeds. The sponginess of the pads, flexing of pivots, repetitive cable stretching and cable friction, leaves me consistently dissatisfied. The hydraulic discs I've ridden do provide a noticeably improved modulation, but I've not yet been motivated enough to justify the install... even though I do have a vintage pair of Hope Mini's stashed somewhere. But I'm picky that way, I guess. And this is,... by not means,... an endorsement or recommendation.

 

[lnanek]

Yeah, I have full hydraulic discs on only one bike in my garage. Cable actuated hydraulic disc with compressionless housing on all the rest (even though Chalo also isn't in favor of hybrid, saying it's the worst of both options), and V-brake only on one (with lots of spare parts in bins since I often have to order a model number to figure out arch size).

All options can lock the wheel and skid when well adjusted, so at that point you don't need more strength anyway, just more modulation, less frequent adjustment requirements, not needing to learn how to bleed hydraulic systems, better heat handling, etc..

I've only had to bleed once every few years, though, so that disadvantage to hydraulic and hybrid is not a big deal to me. Hub motors often do place the rotor odd offsets, though, like Bionx. So in the ebike world fitting discs the first time can be more painful. Stack of washers under the rotor isn't considered safe either.