A faultless bike and a little fettling

[RobF]

This forum has been looking more like a trade paper of late, so time for a thread about a user's ebike.

The user is me and the bike is my Rose/Bosch Xtrawatt trekking bike.

I've covered more than 600miles now and have been planning to post an update for some time.

Happily, there's not much to say on the reliability front because the bike has been faultless.

The ride is a matter of taste, but I like the smoothness and comfort - partly due to the near balloon tyres - and the simplicity of the Bosch system.

It's most like ordinary cycling of all the ebikes I've tried, so it's largely a matter of setting it to tour or sport, leaving me free to enjoy the ride.

The fettling part of this post relates to the Alfine 11-speed gear hub.

Firstly the simple part, it was due an oil change and that's been done using the £30 kit off ebay.

The more complicated fettle resulted from my wish to reduce the gearing, which is just a bit too high.

The Bosch assist needs the pedals spinning at a reasonable cadence to give of its best - like proper cycling, as I said.

Trouble was spinning first gear equated to a speed of 7-8mph, too fast for a 'granny ring' hill climb.

My man Vince told me the 20-tooth rear sprocket can be replaced with a 23-tooth one, which strictly speaking is a Nexus.

We fitted that - and a new Dura Ace chain - but that revealed a, horror of horrors, design compromise with the bike.

The chain was either too long, or with a couple of links taken out, too short.

Reason being the amount of adjustment on the bike is limited not by the neat pair of slots on the drop-outs as it should be, but by the balloon tyres.

Move the wheel a few mms one way and the tyre fouls the mudguard, a few mms the other, and it fouls the chainstay brace.

The solution was a chain tensioner, Shimano make an Alfine one, but this being bike fettling it didn't fit out of the box.

Vince had to cut a crescent of metal out of the tensioner's mounting plate to avoid it fouling the rear of the two bolts on the dropout.

That done, it fits as it should.

I've not done an extended test, but first gear now equates to under 5mph at a good cadence.

I comfortably hit 15mph in 7th/8th instead of 5th/6th, so there's still plenty at the top end.

The other bit of good news is the spare links from the new chain added to the old one means the old one is now long enough for a spare.

The pics show before and after, and I've added a general one of the bike in full shopping trim so that casual readers can see what I'm talking about.

 

[shemozzle999]

It is the start of the silly season Robf, it happens about the same time at the end of season at year end.

 

[RobF]

Readers with long memories will recall one of the reasons I looked at the gearing was my failure to climb Iveston Bank, near Consett in County Durham.

Well, me and that blasted hill met again earlier today.

The news is good, but not 100 per cent so.

I managed to get within about 30 yards of the top before baling out into a handy farm driveway.

The driveway is level, which enabled me - after a few minutes slumped over the handlebars wheezing like a sick miner - to restart.

So I did climb Iveston Bank, albeit with a break.

Thanks to the lower gearing, I got much further up than I did last time, and was in a position to tackle the last bit far sooner.

To get the best out of the Bosch system, I was still doing just over 5mph in first, which is a bit faster than would be ideal for steep climbing.

Now that I have a chain tensioner, the world of bicycle gearing is my lobster so I could fit a smaller ring on the front - there are plenty of different sizes online.

That may happen, but I think my preferred option is to try to get a bit fitter - and lighter - which should enable me to climb the bank in one hit.

I thought about having another go this morning, but I had more exciting fish to fry.

Looks like I finally have a working dongle.

We shouldn't mention the d-word in here, so I will post about that in the naughty boys' forum.

 

[mike killay]

Sorry,
reading this business of having to keep up a certain cadence in order to get enough assistance puts me right off the Bosch system.

 

[RobF]

Sorry,
reading this business of having to keep up a certain cadence in order to get enough assistance puts me right off the Bosch system.

Fair enough.

Obviously, I think I am right about the cadence.

But if you fancy a Bosch bike in other respects, you ought to try one to confirm - or otherwise - my opinion.

One doesn't hear of many problems with Bosch bikes, so it would be a shame to miss out on a good, reliable bike just on the basis of my riding impressions.

 

[Artstu]

Sorry,
reading this business of having to keep up a certain cadence in order to get enough assistance puts me right off the Bosch system.

that's your loss. however having said that I find myself spinning too fast at times to gain full assistance, so change up a gear to gain more assistance at a lower cadence, it feels counter intuitive to do so at times. I really like the Bosch, it shares the load, but isn't suitable for the lazy and weak.

Nice to see the tensioner Rob, although I seem to remember you saying something like "why would you want a tensioner?" or something like that hey we could have swapped cogs with me going the other way.

 

[RobF]

that's your loss. however having said that I find myself spinning too fast at times to gain full assistance, so change up a gear to gain more assistance at a lower cadence, it feels counter intuitive to do so at times. I really like the Bosch, it shares the load, but isn't suitable for the lazy and weak.

Nice to see the tensioner Rob, although I seem to remember you saying something like "why would you want a tensioner?" or something like that hey we could have swapped cogs with me going the other way.

Yes, I was trying to recall the ins and outs of your tensioner experience when I was working through my problem.

Didn't you have to do some fabricating?

Some Rohloff or NuVinci ordinary bikes have tensioners from the factory, some don't.

Given what I know now, I regard the existence of a tensioner as an indication of a well-made bike.

Chain tensioners - they're great.

 

[Blew it]

Obviously, I think I am right about the cadence.

You're spot-on with the need to spin the pedals to achieve good hill-climbing with the Bosch system, and this applies equally to any drive incorporating a genuine torque sensor....and I'm not talking about super-high cadence. My first experience with the Bosch drive on my Haibike Trekking was none to impressive, until I tried a different technique.

Initially, I was slugging it out in too high a gear, dropping a couple of ratios and increasing the cadence to a sustainable 75 rpm, the individual power pulses blend into a continuous stream of assistance. Quite simply, the more power pulses per revolution of the driving wheel, the greater the climbing ability. As a matter of interest, in the highest setting, the classic Bosch drive assists up to a cadence of 110 rpm, I's a pity I cannot manage to spin that fast, the climbing ability must be fantastic with so many power pulses per revolution of the back wheel.

Incidentally, I really wish my Haibike Trekking was fitted with a chainguard like yours...I could dispense with my trouser clips if it did.

Haibike Trekking at Barbury Castle

 

[Artstu]

Didn't you have to do some fabricating?

I did yes, my drop-outs are horizontal, and the little tab on the tensioner plate is set up to sit in the vertical drop-out like on yours, that combined with the axle flats means I had to cut the tab off to get it to work. A tensioner is essential in my opinion, especially on a chain eating e-bike.

My friends Nexus equipped bike has an eccentric bottom bracket housing to achieve the tensioning, and that's a pain, but it has a derailleur hanger, so I'll fit a tensioner to that one day.

 

[RobF]

You're spot-on with the need to spin the pedals to achieve good hill-climbing with the Bosch system, and this applies equally to any drive incorporating a genuine torque sensor....and I'm not talking about super-high cadence. My first experience with the Bosch drive on my Haibike Trekking was none to impressive, until I tried a different technique.

Initially, I was slugging it out in too high a gear, dropping a couple of ratios and increasing the cadence to a sustainable 75 rpm, the individual power pulses blend into a continuous stream of assistance. Quite simply, the more power pulses per revolution of the driving wheel, the greater the climbing ability. As a matter of interest, in the highest setting, the classic Bosch drive assists up to a cadence of 110 rpm, I's a pity I cannot manage to spin that fast, the climbing ability must be fantastic with so many power pulses per revolution of the back wheel.

Incidentally, I really wish my Haibike Trekking was fitted with a chainguard like yours...I could dispense with my trouser clips if it did.

Haibike Trekking at Barbury Castle

Interesting stuff, Blew It.

I reckon my cadence on a steepish climb will be no more than 50rpm, now equating to about 5mph in first.

Seems I could get more climbing power from a higher cadence, but to achieve that I will need to lower the gearing a bit more.

What with this and the dongle, I think I'm 'tinkered out' for the time being, so any more gearing mods will have to wait.

Like your bike, by the way.

I would say that because I like German trekking bikes, but there's something to be said for the Haibike's 'upside down' motor.

I'm mostly a road/cycle path rider, but I do have to watch ground clearance in some situations.

 

[103Alex1]

that's your loss. however having said that I find myself spinning too fast at times to gain full assistance, so change up a gear to gain more assistance at a lower cadence, it feels counter intuitive to do so at times. I really like the Bosch, it shares the load, but isn't suitable for the lazy and weak.

That's the key thing really. It's a fallacy to think that these systems make steep climbing essentially 'effortless' or even a breeze for people who are not conditioned cyclists with a good level of fitness. If I don't cycle for a week say and then take the 250W crank drive bike up long steep climbs I feel it far more than with a more powerful hub motor. When I rode it every day with regular longer trips (Spring) I got used to the climbing but that doesn't happen any more owing to my movements and I have grown to far prefer riding the other bike. It has never left me gasping but I can break a sweat whenever I choose to. Whilst it's all relative and these systems (for what they are) definitely rank amongst the best, only a weight loss (unnecessary in my case !) or fitness drive would make me pick the default (far) harder work option for long steep climbs.

There is basically only so much you can get from these systems whatever you do to the gearing and sustained steep climbs will knacker you out very effectively. So if you want to climb mountains with them then unless you are willing to get (and more importantly stay) in condition steep hills are always going to be tiring and leave many out of breath. Commuters with lots of hills and people using the bikes as daily form of transport likely find it far easier to stay in condition than people who use the bikes on such slopes more for leisure or occasional use.

After about 50:50 split of miles on a crank drive torque-sensored Bosch-like system and a powerful hub system with a throttle it is only the latter which can really claim to 'flatten hills' and get you home energized and envigorated rather than knackered. So I guess that puts me in the "lazy or weak" category now

 

[Blew it]

So I guess that puts me in the "lazy or weak" category now

It does nothing of the sort!

Based on your experiences with a production machine, you set about building a machine tailored to suit your own specific needs. I doubt I need to remind you, that build involved a huge amount of patience, research and sourcing before coming to fruition. You went the extra mile to produce an extra special machine that continues to deliver the required performance....long may that continue.

 

[Deleted member 4366]

It does nothing of the sort!

Based on your experiences with a production machine, you set about building a machine tailored to suit your own specific needs. I doubt I need to remind you, that build involved a huge amount of patience, research and sourcing before coming to fruition. You went the extra mile to produce an extra special machine that continues to deliver the required performance....long may that continue.

Alex makes some good points, and, indeed, he has a very high torque hub motor; however, there are production bikes that also have high torque, which can give that torque with very little effort: The Ezee bikes with the big motor; the Kudos Tornado; the Woosh Big Bear (though I've not tried it to confirm); etc.

I can't understand the obsession with torque sensors and torque control systems, which force you to pedal hard to get high torque. I'm sure Bosch could get a lot more customers if they gave the option of a speed control system.

 

[RobF]

I can't understand the obsession with torque sensors and torque control systems, which force you to pedal hard to get high torque. I'm sure Bosch could get a lot more customers if they gave the option of a speed control system.

I suspect Bosch set out to integrate the assistance into the cycling experience as seamlessly as possible.

In that respect, I reckon they've succeeded.

Worth remembering we are talking about extreme - certainly for me - conditions.

Iveston Bank has a reputation among cyclists around here for being a brute.

Put another way, I walked down the steepest part of it because I didn't feel able to control the bike while riding.

Also, I'm still too heavy and not particularly fit - I reckon the likes of Stu and Blew It would get up Iveston on a Bosch without too much bother.

Besides the ride of the Bosch, I like the system for a few other reasons, nice big display, easy to control, decent range, and the crank drive and battery mount means I can ride a close to standard bike.

Not that I'm obsessed with crank drive, I could happily live with a well set-up hub drive, but I it would need to be 500w and not restricted.

 

[Blew it]

I reckon the likes of Stu and Blew It would get up Iveston on a Bosch without too much bother.

Ooh! don't know about that, depends how steep it is.

My own Trekking bike benefits from the brilliant SRAM DUAL Drive, 27 ratios with out the need for multiple chain-rings. I quite often ride an entire route with the hub element in overdrive allowing the wear to be shared over the larger cogs of the cluster. There is a detectable loss of efficiency when using the indirect overdrive, but this is easily offset by the power available from the Bosch drive.

When I started riding E-bikes over six years ago, the machines were all hub driven. Whilst I regained some of the strength in my legs, It was only when I changed to torque sensor center-drives that I began to build significant leg power. Currently, I'm riding at 73kg, so I may have an advantage when hill climbing.

If I was to attempt your hill, I would choose to ride the latest addition to the stable, it goes up hills like a dose of salts. Last week I had a hairy moment on it climbing Lady Lane....the back wheel spun out on the wet leaves in 'Turbo' mode, good fun though!!

AVE XH-7 Urban Cruiser