My Saracen Tufftrax came with a 3x8 drivetrain - three chainrings at the front, eight sprockets at the back. Twenty four gear combinations in theory, maybe eight you actually use in practice.
For most people that’s fine. For me it’s a problem. With everything on the left hand side - brake lever, front shifter, rear shifter - it was already cramped before I started thinking about adding a dropper post lever. Something had to go, and the front shifter was the obvious candidate.
Before going down the modification route I did look at replacement bikes. Something more modern with a 1x drivetrain already fitted would have solved several problems at once. But decent bikes with the right spec aren’t cheap, and I’ve already made a number of changes to mine that work well for my situation. Starting again with an unknown bike felt like a backwards step. Modifying what I had made more sense.
That meant going to a single front chainring. Which meant thinking properly about gears for the first time in years.
Why Not Just Remove the Front Derailleur and Call It Done?
This was my first instinct. Leave the chain on the middle ring, remove the front derailleur and shifter, job done.
It works, up to a point. The middle ring on my bike is 34T, which is a usable size. But a standard middle chainring isn’t designed to run without a front derailleur - the teeth aren’t shaped to retain the chain on rough ground. On smooth paths it’s fine. Hit a bump and the chain can drop off.
From what I could find, the answer is a narrow-wide chainring. The teeth alternate between narrow and wide to match the inner and outer links of the chain, which apparently keeps it seated without needing a derailleur.
So a new chainring was going on regardless. Which opened up the question of what else to change at the same time.
The 11 Speed Rabbit Hole
My thinking started with 11 speed. More gears, wider range, modern standard. Seemed like the obvious upgrade.
The problem is the freehub. Shimano’s 11 speed MTB cassettes need a different freehub body than the standard HG freehub that’s been used for 8, 9 and 10 speed cassettes for years. My existing wheel almost certainly had the older standard. Which meant either a new wheel or a new freehub body - and finding out which required removing the cassette to inspect the hub, which required tools I didn’t have yet.
Then there’s the cost. A proper 11 speed conversion - new cassette, new derailleur, new shifter, new chain - adds up. And if the wheel needed replacing too, the numbers got uncomfortable for a bike worth maybe £150-200.
10 speed changed the picture entirely. The Shimano 10 speed cassette uses the same HG freehub body as 8 speed. No wheel changes needed. The parts are a step up in quality from the stock components, the cost is reasonable, and the gear range available is genuinely useful.
Understanding What I Actually Had
Before deciding what to change, I needed to understand what my current gear range was actually giving me.
I came across the concept of gear inches when trying to make sense of this - a single number that represents how hard or easy a gear is, taking into account both the chainring and the rear sprocket size. As far as I can tell, bigger number means harder gear, and it lets you compare completely different setups on a level footing.
Working it out for my current setup:
- Lowest gear: 24T front ÷ 28T rear × 27.5” wheel = 23.6 gear inches
- Highest gear: 42T front ÷ 11T rear × 27.5” wheel = 105 gear inches
The low end was adequate - I could get up hills, just about. The high end was fine for descending.
The problem was everything in between. With only 8 sprockets across that range, the jumps between gears were noticeable. And I was struggling on local hills in a way that suggested I could do with something lower.
Choosing the Right Cassette
Looking at what the Shimano Deore 10 speed 11-42T cassette actually gives you, the sprockets run:
11, 13, 15, 18, 21, 24, 28, 32, 37, 42
Comparing that to what I had - roughly 11, 13, 15, 17, 19, 21, 24, 28 on the 8 speed - the top end looks very similar. The smaller sprockets are much the same as before. But then there are three sprockets at the bottom of the range - 32, 37 and 42T - that I simply didn’t have before.
From what I could work out, those are the climbing gears I was missing.
New lowest gear: 34T front ÷ 42T rear × 27.5” = 22.3 gear inches - slightly lower than before.
The Chainring Size Question
This took more thought than expected.
My first instinct was a 32T narrow-wide chainring - a common size for 1x conversions. But working through the numbers, 32T gave me an unnecessarily low bottom gear and a noticeably reduced top end compared to what I had.
Then I realised something obvious: my middle ring is already 34T. It’s the gear I spend most of my time in. I already know how 34T feels. Converting to a 34T narrow-wide means the bike feels exactly the same to ride, just with three extra climbing gears available at the back and no front shifting to think about.
32T would have been a solution looking for a problem. 34T matches what I already ride.
The top end does reduce compared to running the 42T big ring:
- Old highest gear: 42T ÷ 11T × 27.5” = 105 gear inches
- New highest gear: 34T ÷ 11T × 27.5” = 85 gear inches
That’s a real reduction. But in practice, the 42T front ring was only useful at speed on flat or downhill ground. For the riding I actually do, 85 gear inches is plenty.
What I ended up buying
Once the decisions were made, I shopped around all the usual cycle and sports shops but in the end eBay had the best prices for everything. Fingers crossed it’s all genuine. I went with Shimano Deore-level components - a Shimano RD-M5120 rear derailleur (the Shadow+ version with a clutch to reduce chain slap), the CS-M4100 10-speed 11-42T cassette, an SL-M4100 shifter, and a CN-HG95 chain. For the chainring I found a Bucklos 34T narrow-wide that fits the 104 BCD bolt pattern on my existing cranks. I also needed shorter chainring bolts - 6.5mm single-ring length rather than the longer ones from the triple chainset.
Total cost came in just under £130 delivered.
One Thing Worth Knowing Before You Start
Chain sizing for a 1x setup is apparently done differently to a multi-ring bike. From what I read, you thread the chain through the rear derailleur as normal (through both jockey wheels), wrap it around the chainring and the largest rear sprocket - the 42T - then pull the chain taut. This extends the derailleur cage forward. Where the two ends of the chain meet, add two links (one full link) and break there.
The reason for using the largest sprocket is that you’re sizing for the worst case - the combination that needs the most chain. That way the derailleur has enough slack to take up when you shift to smaller sprockets.
Will It Be Worth It?
The front shifting will be gone. One lever to think about, one thing to adjust, one less source of noise and cable stretch. In theory it should be noticeably simpler to ride.
For a bike this age and value, spending £130 to make it work properly for how I actually use it feels like the right call. I’ll update this once everything arrives and I’ve had a chance to fit it.
Some links in this post may be affiliate links, which means I may earn a small commission at no extra cost to you.