The B Works: Correct Chain Length for Gravel, Road, and MTB

Three of the most common questions that land in my inbox:

#1 "Is chain waxing really necessary?"
#2 "Which is the right chain for my bike?"
#3 "And how long does the new chain need to be?"

While the first question can be answered briefly with "absolutely yes," the other two take a bit longer, and unfortunately, the standard answer at first is "it depends." But don’t worry, I can definitely shed some light on the matter.

Don’t be discouraged if the topic seems complicated at first glance. I’ll guide you through it (virtually, of course) and solve the puzzle step by step for you.

And if you want to do it really well, then of course nothing beats a waxed chain - for example, one from my derbaranski.shop.

Option number one sounds as simple as it is plausible: You base it on the chain length that was installed by the manufacturer. If everything has worked well so far, this is the most obvious choice. However, this might not always be the perfect solution – for instance, if there was already an error or if something has been changed in the meantime. For example, the cassette might have been switched from 11-30 to 11-34 teeth, or a derailleur cage with oversized jockey wheels and a longer cage might have been installed. At first glance, this might still fit, but it’s worth taking a closer look at the derailleur in extreme gears like 54/34. If it’s almost horizontal and on the verge of tearing off, something is definitely not right. Caution is advised even when shifting up step by step – a chain that is too short often makes itself known acoustically through rattling.

I actually once stood in the field with a buddy when a retrofitted chain was too short – it ended in a derailleur massacre along with a broken spoke. Sounds silly, but for those who wax chains and store them collectively in a box, it’s essential to check the length before installation. Simply laying the removed chain next to the new one helps to avoid such fails. Nevertheless, always count the links! Depending on wear and elongation, you could still miscalculate otherwise.

The following overview clearly shows how much cassette size and derailleur affect chain length. This should always be kept in mind during modifications – and don’t forget with full-suspension bikes: The chain “stretches” when the rear suspension compresses.

No matter what bike it is – in such cases, the use of chain locks that can be reused multiple times is recommended. For example, those from YBN, which I offer in my shop. Those from Shimano and SRAM, on the other hand, are officially intended for single use only – and cleverly, they recommend using a new one each time. Recently, I’ve also added YBN chain locks for Flattop chains to my range.

And how do I handle this on my bikes – and why sometimes differently than recommended?
For bikes with a front derailleur, I like to keep the chain as long as possible. The reason: I want to have maximum flexibility with chainrings and cassettes and not limit myself to a specific configuration due to the chain length. That’s because I change components too often.

During an initial installation, I place the chain on the small chainring in the front and on the smallest sprocket in the back with 11 teeth. I only lightly tension the derailleur in this position. This prevents the chain from flapping around in this „dumbest“ gear, which I hardly ever use anyway. At the same time, there is enough clearance on the top – on the big chainring and the „rescue ring“ with a 30 or even 34-tooth sprocket (all Shimano!) – without causing damage.

If shifting doesn’t work in this setup: I have disabled all Synchro-Shift and similar Di2 assistance systems. I want to consciously decide myself when the front derailleur moves – and when it doesn’t. Especially with a 34-tooth sprocket, many climbs can still be tackled on the big chainring without immediately switching to the small one (at least here in the north). Much love to my critics in Allgäu with their climbing genes – I love you all too.

It’s a similar approach with my time trial bikes, which usually only have a rather large chainring in the front. These almost always have a special derailleur installed, which in combination requires a longer chain. The classic setup: 58 teeth in the front, 11-30 teeth in the back, along with an OSPW derailleur cage. For me, the original delivered chain length of 116 links always works. This keeps the derailleur under tension on the 11-tooth sprocket, and on the 30-tooth sprocket, there’s still enough reserve – without being horizontal or rattling.