I’d ridden 600km on the Shimano XT set up that came on my Lapierre Overvolt FS700 and went through a chain and an eleven speed cassette in that time. Although the EX1 promises improved wear and more positive shifting I couldn’t get my head around the whole eight-speediness of it; while the range is the same I like having all the ratio options between the top and bottom gears that eleven speed provides.
EX1 versus 2,500km
SRAM moved to eight-speed to aid shifting under the extra load that comes from the motor. The cassette has a shifting profile that keeps the chain in contact with the sprockets as much as possible, meaning the chain’s links mesh with particular teeth on the cassette consistently.
This is done with the aid of a correction tooth that keeps things in sync when shifting up and down the cassette – called the defined link position. This also helps with the chain’s design, as the engineers can shape the inner and outer plates of the chain specifically for the cassette teeth they are likely to meet.
The cassette’s sprockets are 11, 13, 15, 18, 24, 32, 40 and 48, with even spacing higher up the block. It fits on regular freehubs, rather than SRAM's XD Driver.
In practice, eight-speed also means fewer shifts are performed overall and helps prevent chain wear and chain breaks with a straighter narrower chain line, thanks to a narrower cassette.
It took a while to work out how best to use EX1 and get the most out of it as the Bosch Performance Line CX motor works most efficiently when keeping the cadence to the recommended 80-90 revs.
However, the larger jumps between gears in an eight speed versus an eleven speed cassette make for more drastic changes in cadence when shifting, especially noticeable between the 18 and 24 tooth sprockets in Eco mode. It’s not so pronounced riding in Trail or Sport modes but the trade-off of that more powerful mode is a reduced battery life.
On the trail
When hitting the trails I like to go long so the challenge has been to get 50-60km from one battery charge. It has been doable most of the time but terrain can help or hinder that. The 11-48 teeth range allows for a good spin along flat or rolling terrain and that helps battery life, but throw in some big or techy climbs and you need to be strategic in your use of other modes.
If, in contrast, you view an e-bike as your own personal uplift, battery life will be less of a worry — throw it in Turbo mode, get to the top and you’re only ever one run away from home when the red light starts to flash. This means less thought needs to go into riding style, and consequently gear choice.
The single shift operation is designed to prevent wear and make for positive shifting and it delivers — smooth clean changes under power, no double or multiple shifts and no broken chains so far. It was easy to adjust to and only occasionally did I get caught out in the wrong gear at the bottom of a climb, having to click through several sprockets to get back up to cadence one at a time.
This particular feature has been popular with a number of manufacturers, with the single-shift mechanism being used on non-EX1 e-bike drivetrains with regular 11-speed cassettes.
What were the niggles? The chain jumped off the bottom jockey wheel a few times and jammed the rear mech. It happened on rough terrain and when coasting so I’m not sure if chain line or chain length were the issue but it was a pain when it did as the jockey wheel had to come off to release the chain.
Is it value for money? If you look after the chain and change it regularly then yes I think it is worth it - for the record I went through three in 2,500km – priced at £25 (about $33). The front sprocket (£17 / $23) was replaced at around 2,200km but is cheap and easy to replace. The cassette finally died at 2,500km and at £380 (about $510) is somewhat spendier to renew.
Would I have it on my next e-bike? Absolutely. I’m riding back on an eleven speed now and I miss that single positive shifting.