With so many excellent eMTBs on the market there’s never been a better time to buy, but there are lots of questions to answer before investing your hard earned savings: which brand, which model and, possibly the most important – how do I find the right eMTB frame size? We show you what to look for so you’ll get a perfect fitting eMTB.

How are frame sizes defined?

In the early years of off-road riding, bikes were sized according to seat tube length and measured in centimeters or inches, basically depending on whether your frame was European or American. Saddles were barely raised above the top tube and standover height wasn’t even a consideration. After a quick look at your height, shop staff would match you up to the biggest bike that you could fit on and, if you were lucky, adjust your stem to get your reach right.
With the coming of age of the mountain bike, things slowly started to change. Riders needed more room to move and make mistakes, so frames got lower but they were still measured in the same way for several more decades.

Fast forward to 2018 and the constant evolution of how we ride has been matched with advances in technology, totally changing how we size our bikes. Prospective buyers can definitely be forgiven for getting confused by eMTB sizing.
Some brands still separate their sizes with a seat tube measurement, this is more hindrance than help as the 48 cm or 17” measurement means very little by itself. Brands using the simpler XS-XXL range make it a bit easier but one brand’s sizing may differ from another, so you can’t assume that your size will remain the same between brands.

Studying geometry charts can give you an insight into which bikes will meet your needs and can quickly become an obsession, but numbers on a page will only give you an idea of an eMTB’s fit and capability. When it comes to sizing your eMTB, two measurements in particular can be very useful for figuring out the geometry puzzle; stack and reach.

Understandably, riders want the maximum standover height (which is the amount of room between your nether regions and the top tube) available, while keeping enough distance or length between the saddle and the handlebar for a comfortable riding position, this length can be more effectively sized using the ‘reach’ and ‘stack’ measurements on your bikes geometry chart. Reach is the horizontal distance between the bottom bracket and the top of the head tube and stack is the vertical distance between these two points. Using these two measurements can help judge the correct eMTB size, as well as providing a quick way to compare the fit of different models.

For the ladies, female specific sizing and geometry may be available and this can be fantastic for smaller riders regardless of gender. Women looking at buying an eMTB should still consider bikes in the ‘mens’ range, especially if you are of average, or above, height as you may find the fit suits you much better.

When it comes to sizing your eMTB, two measurements in particular can be very useful for figuring out the geometry puzzle; stack and reach.

What about eMTB riders who fit in between two sizes?

Manufacturer’s often offer recommended sizing for their eMTBs and for 95% of riders, these guidelines are pretty spot on. However, there will be riders whose height places them in between two sizes leaving them with a difficult decision… to size up or size down?

If you do find yourself in size limbo on your chosen bike, we would generally recommend sizing up – as long as there is enough standover clearance, this will help the bike’s stability, climbing ability and handling on descents. While this is our recommendation for most riders, if you’re a rider who wants a more agile and active ride, then sizing down can be an option. As eMTBs are heavier, they are inherently stable and riders may find that are willing to sacrifice some of that stability for the maneuverability of a smaller frame. Riders with shorter arms than legs or wanting a more upright riding position may also find a smaller size to their liking as the shorter reach may feel more comfortable.

At either end of the size chart, very tall or short riders won’t have a choice between sizes, they will just have to buy the biggest or smallest eMTB available to them. It sounds simple but if your chosen bike isn’t made in a size that you require, find one that is! Another brand or even model may size much bigger or smaller depending on its geometry, so be open to alternatives.

Once you have chosen your bike, you can fine tune the fit by raising or lowering the handlebar using stem spacers. Saddles can be slid forward to decrease effective reach on a bike that feels too stretched but taller riders must be careful sliding a saddle too far back; this will slacken the effective seat angle and put more weight over the back wheel, making the steering light and reducing the eMTB’s ability to tackle steeper climbs.

Dropper seat posts are now available with stroke lengths of anywhere from 80 mm to a whopping 200 mm, which is fantastic for tailoring a bike to fit different sized riders. However, the design of the bike’s seat tube must allow the seat post to be fully inserted or the advantages of a low standover height are lost, something shorter riders should be especially aware of.

Conclusion

The best way to find the perfect eMTB fit is to visit a reputable dealer with a good range of bikes that you can demo but we know that this isn’t always possible. Not everyone has a great dealer or demo events close by and online-only brands that sell direct to riders are always a compelling option: for the riders not having or not requiring the services of a shop, online size guides are great and most eMTB riders will be very happy with each brand’s recommended sizing. To those who fall in between or outside the sizes, it all comes down to geometry chart detective work, demos and personal preference but, rest assured, the right eMTB frame size is out there!


This article is from E-MOUNTAINBIKE issue #015

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Words: Thomas Corfield Photos: Trev Worsey

About the author

Thomas Corfield

After nearly 30 years of riding and coming from a career in cycle sales, UK Editor Tom is still passionate about everything mountain biking. Based in the Scottish Borders, he enjoys riding everything from solo adventures in the mountains to big social night rides.