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Back at the beginning of 2019 a friend let me borrow his new Ribble Endurance SLe electric road bike to test. Fast forward two years and Ribble cycles have kindly lent me one of their latest SL e models to try out. In this updated 2021 review I will look at the specifications in more detail and also compare some of the heart rate monitor data with riding a regular bike.
When Ribble first released the Endurance SL e electric road bike back at the end of 2018, it was a truly ground-breaking machine. Having electric assist on a full carbon-framed road bike was quite innovative at the time and I was fortunate enough to have a ride on one courtesy of a friend.
Fast forward to 2021 and the SL e has proven to be a great hit for Ribble, and continues to be one of their best-selling electric bikes. Since then the SL e has been joined by the excellent CGR AL e gravel bike and a range of hybrids – including two step-through e-bikes.
For this review, Ribble cycles have lent me one of the latest SL e models – the bike featured in this article is similar to the ‘Pro’ build, but with Shimano Ultegra mechanical (as opposed to Di2) groupset. A Mavic carbon wheelset and carbon finishing kit help to keep the total weight down to a very lean 11.2kg (weighed by myself).
Video review and test ride of the Ribble SL e
The last two years have seen a meteoric rise in the sales of e-road bikes, indeed nearly all of the major manufacturers now sell an electric assist version of their popular unassisted models. Companies ranging from Canyon to Cannondale, Specialized, Trek, Cube, Scott and Orbea (to name but a few). Even the highly prestigious Italian brands like Pinarello and Colnago all have electric road bikes in their range.
So why have electric road bikes become so popular?
Due to the global events of 2020, cycling in general has seen a massive surge in popularity. A lot of retailers have reported a 300% increase in sales and e-bikes have accounted for a very large slice of this. E-road bikes as a niche within the electric bike industry were slow to get off the ground, particularly due to the heavy weight and cumbersome nature of earlier e-bikes.
With the advent of such innovative electric assist systems as the X35 ebikemotion and Fazua Evation, weight and integration became central to developing the new generation of lightweight electric road bikes that not only looked and felt like their unassisted counterparts, but were also lightweight and could be ridden as normal bicycles with the assist only being used when really needed.
E-road bikes like the Ribble SL e Endurance allow riders new to the sport to be able to keep up with fitter friends on climbs and also help riders who are returning to cycling after an illness or injury. They can also be an invaluable training tool allowing the rider to target their training at more specific heart rate zones (when compared to riding a regular bike). Below are two Strava screenshots from an almost identical ride. Top one is my regular steel road bike and bottom is the Ribble SL e – incidentally both bikes weigh about the same (11.2kg).
Where these bikes really come into their own is if you live in a very hilly area. I live in South East Cornwall in the UK and on an average ride I will climb 100ft (30.5m) for every mile (1.6km) ridden.
Not all of us are young, slim and fit any more. I personally returned to cycling after many years of self-neglect, and it was an e-bike that reignited my passion for cycling. I went on to cycle over 13,000 miles over the last three years (on a regular bike), and I’ve rediscovered some of the fitness I had in my youth. But despite losing nearly 30kg in weight through cycling, the relentless climbs in my area do take their toll and I usually need a couple of days out of the saddle after a long ride.
This is where a bike like the Ribble SL e comes in handy. If you’re feeling a bit sore from the previous days riding, then going out again isn’t going to be beneficial for your muscle recovery unless you have an e-bike to take the strain on the hills. This isn’t too much of a problem in a flat area as you can chose the pace and effort you cycle at, whereas if you live in an area with lots of steep climbs you have no option – particularly if you’re a heavy rider like myself.
Ribble SL e Endurance – Specification analysis
Unlike the mid-drive Bosch, Shimano and Yamaha units that power some electric bikes, the X35 ebikemotion motor is located in the rear wheel, so the bike can use a standard pressfit bottom bracket. It could be argued that the sophisticated torque, and cadence pedal assist on the aforementioned motors gives a more natural and intuitive feel, but in all honesty I think ebikemotion have nailed it with their excellent pedal assist sensor which measures 40 pulses per rotation and uses a special algorithm to provide pedal assist. It’s definitely a far-cry from the basic cadence-based pedal assist systems found on some cheap DIY e-bike kits.
The 36v 250w X35 electric hub motor is a geared hub motor. Geared hub motors have their cases connected to the stator through a planetary gear reduction system. For every rotation of the case, the motor inside actually turns many times faster. This allows the motor to work at higher and more efficient speeds, while still allowing the wheel to spin at a comparatively slower driving speed. All this makes for an incredibly compact and efficient drive system.
- The X35 includes its own pedalling sensor that enables the manufacturer to install the desired bottom bracket system. This significantly reduces friction, and helps achieve an incredibly smooth power delivery, offering the user a conventional bike when the electrical system is not switched on. This is not possible on a mid-drive motor like the Bosch system.
- The 250Wh (watt hours) Lithium battery pack has everything in a single unit – motor controller, cabling, battery management system, and it remains fixed on the inside of the downtube. If more battery range is required, up to two external batteries can be connected to the system to reach 750Wh (watt hours), giving a potential range of up to 225km (or 75 km with just the internal battery). Please read my post on electric bike batteries for more information.
- The cells used in the battery pack are the Premium Panasonic NCR18650GA cells – incidentally, this was the battery of choice for Tesla cars, before they started manufacturing their own cells. Here is a test of different lithium cells and the Panasonic comes out as the clear winner!
- The X35 motor offers excellent torque thanks to its internal planetary gear system (up to 40 Nm).
All the functions of the e-assist can be easily controlled by a single button. One press of the button turns the system on and goes into ‘low’ assist mode by default. By double pressing the button you can increase the power output in three increments – low, medium and high assist settings. In medium the LED changes to orange and in high to red – white signifies assist off.
Battery range is indicated by the constant colour of the LED: White (full charge), green (medium charge) and red (low charge). If you want more information is is very straightforward to download and configure the smartphone app – this gives a whole load more information and will record your ride (which can be uploaded to Strava). You can also pair up a heart rate monitor, power meter and other sensors if required.
The ebikemotion app will also tell you how much battery you’ve used and how much you have remaining. You can also alter the characteristics of the assist and I believe it’s also possible to have the motor give you assist based on your heart rate – which is really useful for training purposes.
Motor HUB Drive M1
The X35 ebikemotion M1 hub motor provides a useful push when you really need it. As far as its performance characteristics are concerned, I would say it feels more like cycling with a very strong tailwind and fresh legs. This motor is small, lightweight and efficient and is designed to enhance your ride, not dominate it.
- 36V 250w – Max. Torque: 40N.m – Ratio: 14:1
- Maximum Speed: 26km/h
- 11v & Brake Disk compatible
- Diameter 100 mm – Weight 2.1 Kg – Black
- Spokes: 32/14G
The Ribble SL e Endurance is now available in three primary build options: Sport, which features Shimano Tiagra 10-speed with Tektro mechanical disc brakes. Enthusiast, which features Shimano 105 with hydraulic brakes and carbon fibre finishing kit. Pro, which features Shimano Ultegra Di2 with carbon finishing kit and rims.
The demo model featured in this article was supplied in the Pro build spec, but with Ultegra mechanical (as opposed to Di2) groupset. Needless to say the shifting was absolutely flawless, smooth and precise. The compact 50/34 Ultegra crankset combined with the 11-32 rear cassette gave plenty of gear range for getting up the steeper climbs. You can even spec Dura-Ace Di2 using the custom bike builder.
Shimano Ultegra hydraulic brakes are fitted to the Pro version tested here. The Enthusiast build uses 105 and the Tiagra version uses Tektro mechanical disc brakes. I can only vouch for the Ultegra and 105 brakes as I’ve never ridden the mechanical brake version. The Ultegra brakes on the model tested here worked very well indeed. Bearing in mind, I’m not a lightweight rider and on -10% descents at over 30mph, the hydraulic brakes provided very good stopping power and great modulation. Not once did I experience brake fade and they always provided confident and assured braking power.
Wheels and tyres
This model had Mavic carbon rims with YKSION Pro UST 700×28 tubeless tyres. During the main test ride the road conditions weren’t perfect, with a mixture of dry areas, standing water, mud and patches of ice in the shade. I had to ride slower than usual on the bends, but the tyres felt grippy and handled the rough Cornish back lanes with relative ease. On the main road sections they rolled incredibly well on the smoother tarmac.
Based on the latest lightweight Ribble Endurance SL frame platform, the SLe has been designed around a carefully considered geometry resulting in a frameset that offers stability, comfort and great handling with enough adjustability to suit both endurance riders and those looking for a more performance optimised riding position.
The frameset is manufactured from a selected blend of Toray’s T1000 and T800 carbon layered to an exacting specification using an advanced monocoque mould technology incorporating an EPS inner core system which ensures complete consistency of the structural integrity of the fibres and resin throughout the frame. This system also eliminates excess material on the inside of the frame.
The profiles and shapes designed into the frame are all there for a specific performance reason, from the box section down tube and chain-stays enhancing torsional stiffness to the seat post and seat stays designed for vertical compliance and vibration absorption, this frame is the epitome of design and attention to detail.
This demo version has the Level 5 integrated carbon handlebar/stem and carbon seat post along with a Fizik Antares saddle – all very lightweight and excellent quality.
Ribble SLe Test ride and first impressions
This is the second e-bike Ribble cycles have kindly sent me to test out (the first being the CGR AL e gravel bike). The Endurance SL e arrived very well packaged and the first thing that struck me was how light the box felt.
Everything was well-packaged and it took less than 10 minutes to remove the bike from the box and fit all the necessary components (handlebars/stem and seat post). Once I had fitted the pedals the only thing that needed to be done was fully charge the battery. The charging port for the internal battery is neatly fitted where the downtube meets the seat tube (photo below).
Once the battery was fully charged (within about three hours) it was just a matter of waiting for a decent bit of dryer weather to test the bike and film some ride footage – unfortunately it was going to be a long wait!
The Ribble SL e Endurance is a thing of beauty, at a first glance you wouldn’t even notice it’s an electric bike (the small hub motor is obscured by the 11-32 cassette and brake disc). The paint finish is impeccable and I definitely prefer the metallic anthracite colour over the pearlescent white option – you can even customise the paintwork if you choose.
I’d originally planned to go for a longish test ride of around 60 miles, but due to the poor weather and the kids being off school, I’ve had to make do with a couple of shorter, local rides. The screenshots below come from the comparison ride I did with my old Dawes road bike over one of the test routes.
On my first ride, I used the lowest power setting for the first half of the ride and full power for the second half. The lowest power level provides a very subtle but useful boost for climbing hills. My heart rate was noticeably lower (when compared with riding my regular bike) but I still felt like I’d had a reasonable work-out.
As expected, my heart rate was lower while my speed was higher on the climbs. Another interesting observation was my heart zone when riding the Ribble was more in the fat burning zone (zone 2) which is approximately 70% of my max heart rate. Whereas riding my regular bike I spent a higher percentage of the ride in zone 3. Below are screenshots of a short hill climb segment. The Ribble is on the left – the climb took 3:47 on the SL e (in full power mode) with an average heart rate of 139 bpm (max 149bpm) vs 5:17 and 148 bpm (153 bpm max on my regular bike).
Riding above the assist limit
One factor of particular importance for e-road bike riders is how the bike performs beyond the electric assist cut-off point which in the UK and EU is 15.5mph (25km/h). Traditionally electric bikes have been harder to pedal once assist stops – this is down to a number of factors, but the main culprit is the extra weight. With a lot of e-hybrid and mountain bikes weighing in at nearly 25kg, riding one of these bikes is more akin to riding a loaded touring bike.
My first impression of riding the Ribble with the assist off (or above the assist limit) was to me it felt like a regular bike. In fact, I thought it felt very responsive to pedalling input in all situations (even climbing). This is very subjective though and a much smaller rider than myself may notice the extra weight. Both of my regular unassisted bikes weigh about the same as the SL e. Below is a comparison of me riding above the assist limit on a short, flat Strava segment on the Ribble and my Dawes steel road bike. The times were 1:47 for the SL e and 1:39 for the Dawes – as you can see the difference is minimal and may have been influenced by wind speed as both runs were done on different days.
I’ve thoroughly enjoyed my time with the Ribble SL e Endurance Pro. It really is a great bike and my opinion hasn’t changed since I first tried one out a couple of years back. The great thing about the Ribble is you don’t really need two bikes. It can be used as a regular bike or you can use it with the e-assist whenever you need it. It’s like having a normal bike and an e-bike all rolled into one!
It would have been nice to take it for a really long ride, but the weather and current situation have made that difficult. I do know several very satisfied owners who regularly do 100 mile plus rides and only use the assist during the later miles when fatigue sets in. Bearing in mind that the average 100 mile ride in Cornwall can often mean nearly 10000ft (3000m) of climbing.
Some people say that the extra weight of an electric road bike means the assist becomes pointless as any gains on the climbs are lost when riding above the 15.5mph speed limit – I would have to strongly disagree with this – if you’re like me and on the heavy side, two or three kilos isn’t going to make an awful lot of difference. The non-electric version of the SL e weighs in at around 8kg which is just over 3kg lighter than the electric version – if I were to make some changes to my diet and increase my cycling I could lose that amount of weight within a couple of weeks.
The bottom line is the Ribble SL e is fun to ride, whether you use the assist or not. If feels responsive, the components work flawlessly and it’s surprisingly comfortable – its geometry is definitely on the sporty side of endurance, but I found it really soaked up the lumps and bumps on the Cornish country lanes.
Would I recommend one? If you’re a road cyclist who wants to ride a bit further or maybe tackle more demanding rides then most definitely. If you are returning to cycling after an illness or injury or you simply want to change your lifestyle, lose weight and get fitter, the SL e is an invaluable training tool. Make no mistake it’s not a free ride, if you’re after an e-bike that’s going to give you a massive boost, then you’d probably be better off with something that uses a Bosch or Shimano Steps motor.
Buy Now: Ribble SL e Endurance
Thanks for reading and if you have any questions or you already own an SL e, please comment below and I will reply within 24hrs.