Bosch cx vs Bosch sx.

Greetings everyone.

Could use some advice please regarding my next Ebike.

For starters I am 77 years old. For the last seven years I have ridden Cube and Trek cx powered ebikes, my current one being a Trek Powerfly 5. It’s a great bike, but heavy and not that manourabel, at least not for me.

I am looking for something under 20kg and from my limited research it looks to me like I need something powered by a sx motor.

I currently use mostly tour mode, probably 80+% of the time, and turbo mode on the few really steep hills around here. I have breathing issues so need assist nearly all the time.

I ride only on the road, and straight bars suit me as I find them more comfortable.

I have my eye on one of the new Cube carbon emountain bikes, which happens to have an sx motor.

I have not been able to find reviews on what I am looking for, so asking the knowledgeable members here.

What’s the thinking on me being able to ride at least 40 miles on it with possible one or two steepish climbs en route.

I think SX might be a mistake for your needs. 55Nm maximum torque instead of 85Nm. Is the few kilos weight saving on the bike really worth that reduction? In all up weight terms you only save about 5% because the rider is most of the weight.

If manhandling the bike is your reason for wanting a lighter one, fair enough, but otherwise I would prioritise power over weight.

If you go with the SX and regret it, your get out of jail free card is to change the gearing. I changed 9 speed with 11-36T for 11 speed with 11-51T, and can climb anything, but slowly!

Range is all about the battery capacity. Don't settle for less than the 625Wh or so that is now very common, and if you can get a 750Wh you're laughing at the miles.

This certainly won't apply to everyone, but very much applied to a good friend of ours (under 50, but relatively weak muscles), and may well apply to OP.

She tried a quality Bosch bike with battery on the front tubes. After the good test ride we were standing on the pavement with the bike when she had to move it to let someone pass. Really difficult, she just couldn't lift the front to manoeuvre it.

Tried with a similar bike with battery on the back rack; much the same weight. Much less refined according to current political correctness, theoretically giving a much less stable ride. However, the ride was quite stable enough, and she found the bike MUCH easier to handle when not riding.

Consider https://wooshbikes.co.uk/?santana3

Thanks for the reply Matthew.

I think in the back of my mind I was thinking 55nm of torque wasn't going to be suitable.

As you can imagine I don’t want to spend a fair some of money for something that isn't going to work for me.

Lowering the gearing wouldn't help either I think, so need to give it some more thought.

The bike I had in mind has a 400wh battery but you can add a 250wh range extender and still end up with a comparatively light ebike.

What I really want is an ebike with the new Bosch cx performance motor, that weighs somewhere around 15kg and has at least a 650wh battery....as of yet I am not able to find anything that ticks all the boxes.

This certainly won't apply to everyone, but very much applied to a good friend of ours (under 50, but relatively weak muscles), and may well apply to OP.

 

She tried a quality Bosch bike with battery on the front tubes. After the good test ride we were standing on the pavement with the bike when she had to move it to let someone pass. Really difficult, she just couldn't lift the front to manoeuvre it.

 

Tried with a similar bike with battery on the back rack; much the same weight. Much less refined according to current political correctness, theoretically giving a much less stable ride. However, the ride was quite stable enough, and she found the bike MUCH easier to handle when not riding.

 

Consider https://wooshbikes.co.uk/?santana3

just get a dongle to remove the speed limit as will be like a new bike then attack it with carbon parts

I did chip my last bike, and yes it did go a bit faster but after a while I didn't really see the point (for me.)

You would need a lot of carbon bits to lighten a bike the weighs probably 26ish kg to start with.

https://www.e-bikeshop.co.uk/products/electric-bike-haibike-xduro-amt-pro-2014

its just under 23kg and geared to 40 mph but on most new bikes if you donglke it you cant go much bigger at the front mine is eqv to 52t

https://www.e-bikeshop.co.uk/products/electric-bike-haibike-xduro-amt-pro-2014

 

its just under 23kg and geared to 40 mph but on most new bikes if you donglke it you cant go much bigger at the front mine is eqv to 52t

Looks nice but am not interested in speed and only ride on the road, so a FS bike would be a waste I think.

that goes faster than any road bike not 1 has managed tp pass me in ten years.

a diy bbshd would be cheaper and lighter as m8s bike with a batt double the size of nine is same waight looks naff tho.

https://www.pedelecs.co.uk/forum/threads/stolen-gloucester-town-centre-giant-bafang-diy.45980/

I've just finished my latest conversion for some off road fun, brand new Forme Curbar Pro 29er MTB hardtail (£230 deal on ebay) with a Bafang BBS01b 250w 36v middrive (my new spare motor picked up on a deal at about £200 a couple of years ago) and 17.5ah battery (one of my existing).

Weighs in at 22kg and it's an XL frame and with a dropper seatpost. A smaller lighter donor bike should see you comfortably sub 20kg. The bbs01 is 85Nm and good range from the 630wh battery.

I've just finished my latest conversion for some off road fun, brand new Forme Curbar Pro 29er MTB hardtail (£230 deal on ebay) with a Bafang BBS01b 250w 36v middrive (my new spare motor picked up on a deal at about £200 a couple of years ago) and 17.5ah battery (one of my existing).

Weighs in at 22kg and it's an XL frame and with a dropper seatpost. A smaller lighter donor bike should see you comfortably sub 20kg. The bbs01 is 85Nm and good range from the 630wh battery.

 

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That looks great! Did you encounter any problems with the BB? Chainline?

I reckon a cadence sensored system would make things easier for the OP. Torque sensored seems far too much hard work for my liking (any work is too much for my liking). Of course the wonderful thing about the BBSXX(X) series is their programmability, when they're fully programmable: With that gearing, I imagine 720 legal Watts would get that bike up any hill no sweat.

For starters I am 77 years old.

That's very impressive. I doubt I'd be able to manage with a torque sensored system, if I ever get to your age. I reckon what's challenging you is probably keeping you fit, and if you went easy peasy cadence sensored, your fitness may deteriorate.

That looks great! Did you encounter any problems with the BB? Chainline?

 

I reckon a cadence sensored system would make things easier for the OP. Torque sensored seems far too much hard work for my liking (any work is too much). Of course the wonderful thing about the BBSXX(X) series is their programmability, when they're fully programmable: With that gearing, I imagine 720 legal Watts would get that bike up any hill no sweat.

I originally bought the bike not with the intention of converting, but couldn't resist the deal with the spec of the bike. The original chainwheel was a 32t, so I thought I would get chainline issues, but as it turned out, it's running sweeter with the stock 44t bafang chainwheel, which is closer to the chainstay and there's no need to go for a 40t lekkie one which I originally thought I might need. 10spd cassette 11-46t so plenty of low down gearing. Shifting is sweet and crisp and no apparent rubbing suggesting chainline issues. I think the larger 44t chainring has help in that regard compared to the original 32t

I even had to space out the motor with a 1mm spacer on the drive side as the motor was just touching the chainstay when tightened up.

Only completed the build this week, looking forward to giving it a proper run in the forrest over xmas

You would need a lot of carbon bits to lighten a bike the weighs probably 26ish kg to start with.

matthewslack made the excellent point in post#2 "If manhandling the bike is your reason for wanting a lighter one, fair enough, but otherwise I would prioritise power over weight." You haven't indicated whether you care about the lightness because of riding the bike, or because of manhandling it when not riding. I was pointing out that manhandling problems can be as much about weight distribution as about raw weight.

Yes, you'd never get that bike down to anywhere near 20kg.

 

matthewslack made the excellent point in post#2 "If manhandling the bike is your reason for wanting a lighter one, fair enough, but otherwise I would prioritise power over weight." You haven't indicated whether you care about the lightness because of riding the bike, or because of manhandling it when not riding. I was pointing out that manhandling problems can be as much about weight distribution as about raw weight.

Manhandling my bike is difficult, but manageable. My garage is at the bottom of a steep drive and to get the bike in the way I want, I have to do practically a three point turn to do so. Also on one of my rides there are a couple of tight turns and have to stop and scoot around them, again not a major problem, but most people using the turns just ride around them.

One of the big issues has always been the thought of puncturing. It would be a major problem (for me) repairing it.

I use Continental Contact plus tyres with slime inner tubes and thankfully it has not happened yet. Puncturing twenty five miles from home is unthinkable.

Anyway, as has been pointed out, a lightweight sx powered motor wouldn't be ideal for my needs.

Punctures are a thing of the past for me since I fitted my first pair of Schwalbe Marathon Plus tyres. I still carry pump, tube and tools on longer rides just in case, but 5,600 miles and no flats. Before them, 15,000 miles with maybe a puncture every 1,000.

Always use an unpunctured tube when fitting to eliminate the possibility of an old patch failing.

Oh, and on 700c rims I had absolutely no difficulty in fitting them.

Likely a silly idea but...

Yes, you'd never get that bike down to anywhere near 20kg.

...fit smaller carbon fibre wheels for less weight and more torque where tyre meets tarmac? 24" perhaps? If watts and torque were proportional, the legal 720W motor driving my 20" rear wheel is 885.6W, compared to a 26", because my 20" wheel has a 23% torque advatange. And that's why my bike feels so wonderfully nippy.

Manhandling my bike is difficult, but manageable. My garage is at the bottom of a steep drive and to get the bike in the way I want, I have to do practically a three point turn to do so. Also on one of my rides there are a couple of tight turns and have to stop and scoot around them, again not a major problem, but most people using the turns just ride around them.

Smaller wheels are more maneuverable. You could fit a longer seat tube, shorter crank arms, and carbon fibre ape hanger handlebars?

Punctures are a thing of the past for me since I fitted my first pair of Schwalbe Marathon Plus tyres. I still carry pump, tube and tools on longer rides just in case, but 5,600 miles and no flats. Before them, 15,000 miles with maybe a puncture every 1,000.

 

Always use an unpunctured tube when fitting to eliminate the possibility of an old patch failing.

 

Oh, and on 700c rims I had absolutely no difficulty in fitting them.

I used to carry two inner tubes, puncture repair kit and a pump - after over three years and thousands of puncture-free miles, I don't bother anymore. No major problems fitting - secured zipties either side, and squeezed the last bit over by hand. In the unlikely scenario one of my Marathon Plus tyres allows a puncture, I'd simply fold my bike into a bus, taxi, or train.

Edited December 13, 20241 yr by guerney

Punctures are a thing of the past for me since I fitted my first pair of Schwalbe Marathon Plus tyres. I still carry pump, tube and tools on longer rides just in case, but 5,600 miles and no flats. Before them, 15,000 miles with maybe a puncture every 1,000.

 

Always use an unpunctured tube when fitting to eliminate the possibility of an old patch failing.

 

Oh, and on 700c rims I had absolutely no difficulty in fitting them.

I have done near 20.000 miles on my Continental Contact plus tyres without a puncture, but they are an absolute pig to mount. I may give the Schwalbe's a try when mine wear out but that will be a while, they seem to go on forever, probably much like the Schwalbe ones do i suspect.

I have done near 20.000 miles on my Continental Contact plus tyres without a puncture, but they are an absolute pig to mount. I may give the Schwalbe's a try when mine wear out but that will be a while, they seem to go on forever, probably much like the Schwalbe ones do i suspect.

On one set?

On one set?

Ah no, about 10.000 on two bikes but they had a lot of tread left, when I sold the first bike.

I stumbled across this article earlier comparing lightweight eMTBs, might be useful

https://ebike-mtb.com/en/light-e-mtb-test/

I stumbled across this article earlier comparing lightweight eMTBs, might be useful

 

 

https://ebike-mtb.com/en/light-e-mtb-test/

Interesting reading but I am looking for a hard tail. Thanks anyway, much appreciated.

This is 22kg so no lightweight but has probably the most powerful legal motor 108Nm and a big 720wh battery (480wh on small frame size) and now reduced to £1999 so huge saving

https://www.paulscycles.co.uk/bikes/electric-bikes/rocky-mountain-fusion-powerplay-30-electric-mountain-bike-blackred__13798

This is 22kg so no lightweight but has probably the most powerful legal motor 108Nm and a big 720wh battery (480wh on small frame size) and now reduced to £1999 so huge saving

 

https://www.paulscycles.co.uk/bikes/electric-bikes/rocky-mountain-fusion-powerplay-30-electric-mountain-bike-blackred__13798

Wow, pretty impressive figures...108nm torque, phew

You don't need eMTB to ride on roads.

At your age I will prioritize power (as mentioned above) and comfort (step through frame and relaxed up right riding position, good saddle and good suspension).

Till end of my days I will avoid proprietary systems like plague, so no Bosch motors for me unless they will rethink what they are doing.