Polaris OBark

My wife has been getting terrible leg cramps that appear to be directly associated with riding her e-bike. (She does not get them if she rides a conventional bike, or if she takes a break from the e-bike). I decided to try it on a 20 mile commute yesterday (the same route that gives her trouble). It involves about 3000 ft of climbing. Although I did not get cramps, I did notice quite a bit of leg fatigue. (I ride this route regularly, albeit more slowly, on my conventional bike without this happening).

We are trying to figure out what is going on. Is this normal?

We were speculating that it might be due to differences in riding style. For example, the pedal assist has the effect of encouraging the rider to pedal constantly, and to spin at higher RPM. We are both normally mashers.

Raising her saddle made it worse. Lowering partially relieves it, but this is awkwardly low.

This is a Cannondale e-road bike, fwiw, with a Bosch system usually used on the lower settings (eco and tour), which provides a significant boost. The steepest grade is about 18%.

MarcusT

I've seen a lot of ebike specific things, but never cramps. I switch e to non-e constantly and have never noticed a difference in cramps, muscle soreness, etc. I'm guessing it's the bike geometry. The saddle could be farther forward or back. Are crank arm lengths the same? Even the pedals can make a difference. Whatever it is, I'm pretty sure it does not have to do with pedal assist.

Polaris OBark

For me, the geometry is sub-optimal, and I rode it with 5/10s and flat spike pedals, whereas I am more comfortable clipped/cleated in. It has been over 24 hours and I still feel it slightly.

For her, the geometry is hopefully near ideal, but it could be simply the fit.

kahn

You might measure the distance between cranks or pedals. If it is a centralized motor, sometimes to accommodate the space needed for the motor, there is extra space between the crank arms or pedals - Q-distance. That could cause leg symptoms for some folks.

cat0020

Could be crankarm length related.
Generally, ebikes have less available options for shorter crankarms from the factory.
if your wife is smaller in stature, she may require shorter crankarms.
Cadence while pedaling is also a contributing factor to leg fatigue.
Anyway you can determine your cadence while riding?

sloppy12

Q factor and crank length would be the first thing I would look at.

If its a qfactor thing it will probably just go away. Lots of fat bike people have some muscle issues when they switch back and forth.

2old

I'm with MT above, and switch back and forth without any noticeable affect, except that my workout is much easier with the "e", but that's because I'm lazy.

Polaris OBark

Q-factor would definitely bug me. I have a boost drop-bar mtn bike that is a bit of a shock (and I have a relatively wide stance). Wife has hip issues, so Q-factor could definitely be a thing.

I think the crank is 172.5mm. I switched to 165 on my main ride, but I have several bikes with 172.5 and no longer feel anything different.

Polaris OBark

My cadence is definitely faster, and we are both mashers by nature. She has longer legs than I do, FWIW. I think her shortest crank is 170mm, but I would have to double-check. The e-bike has 172.5 mm.

cat0020

For years, I would switch cranks on my bikes according to my flexibility.
In the winter time, when I'm less flexible, I ride with shorter crankarms.
I ride more on the indoor trainers/rollers during the winter, shorter cranks=smaller pedaling circle, I can spin smoother at higher cadence.
Summer time when I ride outdoors more, I'm in better physical condition, I use longer cranks, 172.5 on road bike, 175 on MTB.
But as I get older, I lose flexibility, I have been riding shorter cranks in general, 170mm on my road/MTB, 165mm on my recumbent or folding bike/ebikes.

Q-factor is usually cause of knee issues for me, not so much cramping issue..

Does wife's leg cramp involve calves, quads or hips?

Polaris OBark

I think the cramping is primarily calves and feet. She has a lot of knee and hip problems too (which is why she got the e-bike).

I switched to 165mm cranks on my main ride, but I think we are stuck with 172.5mm for her e-bike. (I'm hoping the assist offsets the 4% difference in torque.)

cat0020

Does wife maintain hydration & nutrition during the rides?
Drink plenty before & during the ride, switch to Gatorade if water is not enough.
Banana, orange & blueberries, or even just mixed trail mix along the ride, take short breaks, eat, drink, recover before cramps starts.

Polaris OBark

Yes.

It is reproducible specifically with the e-bike. She doesn't have the issue with conventional bikes. That is why I wondered if it was something specific to the way e-bikes are ridden, such as higher cadence, etc. I hadn't thought of Q-factor, but it is clearly a major possibility (although I doubt anything could be done).

ThermionicScott 

Perhaps she is getting out of the saddle less often with the e-bike? I know that if I sit and pedal too long, I'll get minor cramps and numbness, but on the fixed-gear, I pop out of the saddle so often to accelerate or get a bit more leverage on hills that circulation is restored.

Polaris OBark

Definitely true for me, but she never seemed to want to do out-of-saddle riding in the entire time I have known her.