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Bosch classic to Bosch CX

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BootsDave, I haven't seen a Bosch powered e mtb that enable a different gear set, ie a front derailleur option, probably because of the drive sprocket size. I think some Yamaha, Shimano and Brose powered bikes can have that option.

Sorry, I have just read SoundWave's post on another thread of an optional double chain ring for Bosch which would also help. It is on this thread http://www.pedelecs.co.uk/forum/threads/is-it-worth-spending-the-extra.26651/page-2

Edited by Tom Rae

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After today's ride, I am certain that the ability to change gearing is essential. I had to stop twice on the climb for a breather! See post in photo and ride thread.

 

Some challenging gradients on that ride, not least because of the terrain.

 

The CX motor is perkier than the Classic, but the difference is not great and I wonder if it will be sufficient to make the difference between having to stop for a breather and being able to ride all the way up.

Lowering gearing would be cheapest option, if you can achieve 15% reduction by changing chainring that would be easiest option.

 

11-40 10spd cassettes are also available to give 10% lower gear.

 

The other option is changing to 1x11spd group set. A 11-42 or 11-46 will give you an 15-20% lower gear compared to your current 11-36 without losing top gear.

 

https://www.bike-discount.de/en/buy/sram-nx-1-11-speed-upgrade-kit-532780/wg_id-391

 

There is also XT 11-46 for $184.

 

I changed my wife's STEPs chainring from 44 to 38t. Made huge difference on steep hills it was struggling with.

 

The other advantage of lower gears is increase range by able to climb in lower assist level. Of course you have reduced speed, don't get something for nothing.

I am amazed that any eMTBs struggles to climb hills.

 

Certainly to the extent of needing to stop for a breather, mine on maximum assistance is like some one else has taken over.

 

I agree with Croxden, I only stop to admire the views.

  • Author

I find that the pace that I need to keep up is just too much for long climbs. If I try to go slower, I just lose momentum. Lower gearing would hopefully mean I could go at a steadier pace.

Trevor, I just can't decide whether it's worth spending money on my 4 year old bike? My battery is down about 10% compared to my wife's year old battery, so that's something else I'll have to consider.

I find that the pace that I need to keep up is just too much for long climbs. If I try to go slower, I just lose momentum. Lower gearing would hopefully mean I could go at a steadier pace.

Trevor, I just can't decide whether it's worth spending money on my 4 year old bike? My battery is down about 10% compared to my wife's year old battery, so that's something else I'll have to consider.

I had this same problem with my Classic powered HT. I found I had to maintain a higher speed than was comfortable because the cadence became too low to climb at a sensible pace and the motor would lose power. I swapped the 42t ring for a 38t which was the only option but it didnt make much difference. My next bike had the Performance/CX motor which came with a 17t front which I swapped for a 15t which made climbing much easier at a slower pace. Buying and changing the front ring is easy and inexpensive and there are many options available and you dont necessarily need to change the cassette. Current bike came with 11-42 and a 17 which is fine for going steady on long steep climbs, especially when riding with an un-powered companion.

I find that the pace that I need to keep up is just too much for long climbs. If I try to go slower, I just lose momentum. Lower gearing would hopefully mean I could go at a steadier pace.

Trevor, I just can't decide whether it's worth spending money on my 4 year old bike? My battery is down about 10% compared to my wife's year old battery, so that's something else I'll have to consider.

It maybe time to up grade. You won't be disappointed in CX drive.

 

The other plus is Bosch should support it for >5yrs given how many are out there.

You won't be disappointed in CX drive.

 

Er, at the risk of repeating myself, if the OP cannot get up hills without stopping on a Bosch Classic, there's no guarantee he will be able to on a CX.

 

I like my Bosch bikes, but I'm not sure they are suitable for the OP.

 

A higher powered pedal only sensor bike would be better.

Er, at the risk of repeating myself, if the OP cannot get up hills without stopping on a Bosch Classic, there's no guarantee he will be able to on a CX.

 

I like my Bosch bikes, but I'm not sure they are suitable for the OP.

 

A higher powered pedal only sensor bike would be better.

Sorry but I disagree here.. My lowest gear on my Scott Classic was so high that on a long steep hill I was forced into working hard to keep the bike above 8mph or so because if I went much slower the cadence was so low the motor would loose power, whereas with the cx system it is easy to lower the overall gearing to enable hill climbing at low speed with a higher cadence. I know exactly what the OP is talking about, just find it hard to put into words.

My classic lowest gear was 42Fx36R.

My CX has 17F (17x2.5=42.5) x 44 which in itself is much lower, but for £20 or so I can change it to 15F (15x2.5=37.5) x 44 which is lower still.

I can now climb at a much lower speed if I need to which is much easier to do.

Just looked on ebay and a 14t is only £12.

Sorry but I disagree here.. My lowest gear on my Scott Classic was so high that on a long steep hill I was forced into working hard to keep the bike above 8mph or so because if I went much slower the cadence was so low the motor would loose power, whereas with the cx system it is easy to lower the overall gearing to enable hill climbing at low speed with a higher cadence. I know exactly what the OP is talking about, just find it hard to put into words.

My classic lowest gear was 42Fx36R.

My CX has 17F (17x2.5=42.5) x 44 which in itself is much lower, but for £20 or so I can change it to 15F (15x2.5=37.5) x 44 which is lower still.

I can now climb at a much lower speed if I need to which is much easier to do.

Just looked on ebay and a 14t is only £12.

 

Aren't you mixing the effects of motors and gearing?

 

Lower gears could be fitted to the Classic bike.

 

I put a smaller ring on the front of my Rose, and a larger one on the Alfine 11 hub at the back.

  • Author
Rob, I think if I was riding on tarmac I could manage it. With the rocky climb, I felt like my speed was too high. From what others have said, it seems lower gearing would help. I like the way the Bosch system rides like a normal bike, how does a pedal only sensor bike feel?
Aren't you mixing the effects of motors and gearing?

 

Lower gears could be fitted to the Classic bike.

 

I put a smaller ring on the front of my Rose, and a larger one on the Alfine 11 hub at the back.

Not easily.. There are only 2 options on the classic front 42 or 38. I bought a 38T but it rubbed on the chain guard when in the lowest gear, plus it was much more difficult to change.

But yes you are right is is all about the gearing, unless the CX motor gives more torque at low rpm's than the classic.

I second the gearing as being the solution, the original bike may be fine with better gearing? It will mean you are travelling slower but pedalling faster thus assisting the motor.
  • Author
I currently have 38f 36r as my lowest gear, I can get a 36t for the front. I could upgrade the rear to an 11/46. That would cost around €250.
Rob, I think if I was riding on tarmac I could manage it. With the rocky climb, I felt like my speed was too high. From what others have said, it seems lower gearing would help. I like the way the Bosch system rides like a normal bike, how does a pedal only sensor bike feel?

 

If you like the natural cycling feel of the Bosch motor, a pedal sensor only bike will feel a bit basic.

 

It would give you access to full power at any cadence.

 

I think the Bosch system is excellent, but it can be a bit of a mixed blessing if you are struggling on a climb.

 

A new CX bike would attack your problem at both ends, a slightly more powerful motor and easier access to lower gears if the factory fit lowest gear is still too high.

 

I currently have 38f 36r as my lowest gear, I can get a 36t for the front. I could upgrade the rear to an 11/46. That would cost around €250.

 

Two less on the front wouldn't make a huge difference, ten more on the back would.

The change to 11spd 11-46 should solve your problem. The money won't be wasted even on this old bike as you can transfer 11spd system over to new bike in future.
38t to 32t on the front may be sufficient, worth a try anyway, cheapest solution by far.
  • Author
Thanks for the input guys. I'm assuming that if I upgrade to an eleven speed, I'll need to buy a group set, not just the cassette.

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