Help with choice of bike to convert please

[Paultr]

I am a 61 year old male with osteoporosis which has caused spinal fractures so am looking for an e-bike to give me some more independence.

Up to 12 hours ago I was going to buy a Whoosh Kreiger having decided that I definitely want crank drive. However I saw my surgeon yesterday and he strongly advised against getting a bike now as the medicine I am taking to strengthen my bones will not be effective for another 6 months and if I fell off the bike I would risk broken bones.

I am converting my disappointment into anticipation of getting a bike next year. I intend to buy a bike and then convert it, probably using the Whoosh kit. This means I can end up with a bike with features that the Kreiger does not have such as better gears, quality disc brakes front and rear and also importantly I can find a frame locally that suits my new shortened torso (sob lol).

So finally to get to my question ! The Kreiger is quite a heavy bike and I believe not so easy to ride unassisted. I could now get a light weight road bike to convert which would be a much nicer ride. However the proportion of the weight of the motor and battery is very much higher if the frame is light.
I don't know exact figures but say the Kreiger weighs 35k and the motor/battery combo is 7 kg it is therefore 20% of the gross weight. However in a light weight flyer the battery/motor would be a much higher proportion. Do you think this will unbalance the bike and spoil the ride and so would I be better looking for a hybrid style with 26" wheels similar to the Kreiger ?

Also any other tips about things to look for when buying a bike to convert to chain drive and possibly even suitable models would be gratefully received ! Nice to meet you all and I look forward to sharing my experiences as they come.

 

[trex]

The Krieger weighs about 23kgs-24kgs including battery, mudguards and rack. The GSM kit is the equivalent of the Krieger motor weighs about 4.3kgs, the battery: 3.5kgs.
If you start with a quality lightweight donnor bike with mudguards, rack and a rigid fork, the converted bike will weigh about 10.5kgs + 1.5kgs for mudguards and rack + 4.3kgs for motor + 3.5kgs for battery and cradle + 0.5kg for controller, wirring and LCD = 20.3kgs, you have a ballpark 20-21kg bike. With front suspension fork, that will be about 22kgs (air suspension) to 23kgs (with quality springs suspension).
The Krieger (and same for any CD bike) is not difficult to cycle without power. There is virtually no drag from the motor.

 

[Nealh]

A few questions ;
Which kit are you looking at BBS, GSM or BPM , I assume BBS or GSM as you have looked at cranke drive.
How much input are you able to give peddling wise ?
Bike wise you have looked at the obvious gears and brakes, what ever bike you decide on the triangle size can be important depending on the battery to be fitted.

 

[Paultr]

Thanks for the replies

@ Trex - so what you are saying is that when you factor in the weight of mudguards, front suspension etc the difference is not that huge. The reason I questioned it was that the bike I have had for years is a 1970's Peugeot racer with lovely Italian chainset & gears and about 5 years ago I bought his 'n hers hybrids with the intention of doing some 2-3 day trails. The difference on the road between those and my road bike was remarkable with the old Peugeot needing a fraction of the amount of energy for a given speed over the wide tyred hybrid. I suppose I have to be realistic now though and the days of fast rides along the promenade in Liverpool are over and comfort is now the order of the day so a hybrid style with front suspension and a comfy seat appeals

btw, thanks for replying to my post. It was your explanation (on various threads) of crank drive being more in harmony with the bike vs the brute raw power of a hub motor that convinced me to go down this route - so thanks

@ Nealh - yes it is the BBS01kit I am thinking of. Maybe 500w but possibly 250w - not sure yet. I will probably go ahead and get swmbo to buy it for me this Christmas just so I am sure of getting a throttle as if I wait until May/June when I should be fit enough to risk riding the bike they may not be available as I believe the legislation changes on Jan 1. I should add that in 50 years of cycling I have never fallen off badly yet but sods law dictates that now when I will undoubtedly be more cautious I will probably be off fairly quickly lol

Edit, you asked how much input I could give to the peddling. The answer is I am not sure. I had my operation a couple of months ago and last weekend I got my bike out and was disappointed to discover I could not even get on it ! At 25" the frame has always been too big for me. I was 6' but now I guess around 5'6" (it is too depressing to check ). It is a bit of a weird situation as obviously my legs have not changed, it is just my torso that has shrunk. This is another reason why I am not too disappointed that Santa is not bringing me a Kreiger in a few weeks time as it may take some effort to find a bike/frame that I am comfortable on. I did like the Kreiger though as it has adjustable handlebars which would bring them closer to me.

 

[Black Dog]

My wife has had a similar experience. In her case it was a triple bypass operation (where they open the ribcage up) that caused the collapse of four vertebrae due to undiagnosed osteoporosis. She has lost about 4" in height as well. She has been advised not to cycle, but of course she has given it a go. She has had a couple of low speed tumbles with no lasting effects. After a period of inactivity, she now (with doctor's permission) does a lot of gym work, mainly rowing and spinning, and her fitness has improved enormously. However, she has decided to leave the ebike alone for a while, as it is quite heavy and she still hasn't got used to the power and speed. I have refurbed her old mountain bike (much lighter and more nimble than the Motus) and as soon as we get a nice day we are going to do a few rides on that to build some confidence. I wish you well with your recovery, as I know that what you have experienced can be quite devastating.