I have a Wilier Triestina Jena Hybrid (gravel e-bike), with a Mahle X35 rear hub 250W motor. It has stock Wilier-branded alloy wheels, and I am contemplating a change to carbon fiber rims, which I have and prefer on my non-e road bike. I have picked up hints that the e-bike system it hard on carbon rims, maybe compromising durability? Does anyone have expertise/experience with this? Second, both my current wheels have a 32 spoke count, and I am wondering if the 32 in front is necessary or optimal on my kind of bike. It is about 27 pounds - does that imply the need for a greater spoke count, both front and back?
Are Carbon Rims Problematic with Mahle x35 Rear Hub Motor?
- Thread starter wmlevine
- Start date
m@Robertson
Well-Known Member
- Region
- USA
Ebikes tend to be heavier, and faster. So they hit things harder. More spokes are not a bad thing in that scenario. I personally typically use 32 hole rims, and completely stay away from bladed spokes (or God forbid c/f bladed spokes). Also brass nipples not alloy. And heavier double-butted spokes like the Sapim Strong, which will happily fit in my DT Swiss hubs (Sapim makes an E-Strong that is so overbuilt it will not). The only ebike wheel where I broke spokes used DT Alpines. Which was a crying shame for the wheel - which had to be restrung - and my wallet.
This whole heavier/harder/faster thing is also why you are seeing a resurgence in the use of steel in, for example, a quality cassette cluster vs. where a cyclist would expect it to be found: on a Walmart bike.
With all of that said, your bike is barely an ebike. The motor outputs 40 Nm which is not a lot. Frame and fork weigh in at under 4 1/4 pounds. The entire motor+battery system come in at 3.5kg, so there's your weight increase for the electrics. I think it goes without saying your speeds aren't going to be elevated on such a bike.
I would not shy away from c/f rims so long as they are biased for strength and not underbuilt for light weight. I'd also go extra strong on the spokes. Maybe you can do 28 still. I'd talk to your wheelbuilder about that once s/he knows your chosen rim. As I am sure you know the best rim is not the rigid one, but rather one that has some compliance built in, so that all factors into an overall picture that I don't think we can know here on a discussion forum. If it were me though I'd err on the side strength and not weight-weeniness.
This whole heavier/harder/faster thing is also why you are seeing a resurgence in the use of steel in, for example, a quality cassette cluster vs. where a cyclist would expect it to be found: on a Walmart bike.
With all of that said, your bike is barely an ebike. The motor outputs 40 Nm which is not a lot. Frame and fork weigh in at under 4 1/4 pounds. The entire motor+battery system come in at 3.5kg, so there's your weight increase for the electrics. I think it goes without saying your speeds aren't going to be elevated on such a bike.
I would not shy away from c/f rims so long as they are biased for strength and not underbuilt for light weight. I'd also go extra strong on the spokes. Maybe you can do 28 still. I'd talk to your wheelbuilder about that once s/he knows your chosen rim. As I am sure you know the best rim is not the rigid one, but rather one that has some compliance built in, so that all factors into an overall picture that I don't think we can know here on a discussion forum. If it were me though I'd err on the side strength and not weight-weeniness.
That is an extremely helpful answer, and covered ground exactly that I needed and could not get elsewhere. I have received the recommendation for Astral Outback rims with 32 double butted spokes, front and rear, with the hubs coming from my alloy wheels. Any experience with Astral, which I understand to be now owned by White Industries. Thank you so much for your great reply above.
JoeDirt
Member
- Region
- USA
You could buy a Reid e-bike with a top speed of 20 mph assist for around 1200 bucks. By the time you get done having someone lace and true those Carbon wheels not to mention the cost of the carbon wheels and wiring and the battery and the throttle you're going to be well over 1,300. That's just my two cents
Stefan Mikes
Gravel e-biker
- Region
- Europe
- City
- Mazovia, PL
If Willier decided it wanted an all carbon e-bike, the brand would have the CF model in the offer. 32 spokes is a well thought engineering decision.
Have you already converted to tubeless? That alone would give you more gain than CF rims.
Have you already converted to tubeless? That alone would give you more gain than CF rims.
m@Robertson
Well-Known Member
- Region
- USA
Based on what I saw in the product pics at the Wilier site, they use 32 in the back and 28 in the front on the factory bike. My Guerilla Gravity enduro 29er used a DT Swiss factory wheelset with 28H front and rear and frankly I never trusted it, even though it never failed me. I replaced the rear wheel with a DT 350 Hybrid hub, an FR560 rim and made it 32H.
I have no experience with Astral, but I do with White Industries, who makes premium specialty components. I took a look at Astral's premade wheelsets tagged for ebike use and they were all 32H/32H. Seems like thats the way to go.
mschwett
Well-Known Member
- Region
- USA
no. you do not need to worry about the rims in any way unless you’re a heavy rider. 27 lb is not a particularly heavy bike, except when compared to lightweight road bikes, but even there the 13lb difference between your bike and a very light bike is not significant compared to the rider weight. the x35 is also not going to add anywhere near the torque a human rider can. I have an x20 road bike with carbon rims, and before that a mid-drive road/gravel bike with carbon rims. zero problems.
pretty sure your motor has 32 spoke holes. How many the front need is up to you. my x20 road bike is 28r and 24f. 25lb bike and 180lb rider. wilier themselves sell various carbon bikes with carbon wheels with mahle hub motors in 24 spoke varieties.
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