Review: Silt AM 29 Alloy Wheels

The flagship of their design is undoubtedly their Ratchet Drive Hub Technology. There are other pieces of genuinely good design throughout the wheel, such as a nicely ramped edge on the well of the rim, which is there to help tires initially seal and then get up on the bead while you inflate them.


Removing the freehub is relatively easy and just requires a 3mm allen key and a 17mm cone spanner. Once loosened, everything is very easy to access and clean, should you need to. If you wanted to remove the affixed ratchet disc, or indeed the bearing behind it, you would need a special tool. Silt makes a point of offering this as cheaply as they can, which I think is a commendable approach. They have a spares section of their website which all seems reasonably priced.


The wheels use a mixture of 6902 and 6802 cartridge bearings. They have a contact seal to face outwards to shield the innards from unwanted grit and moisture. I tested these wheels over an uncharacteristically wet Portuguese winter. Not only did this mean that the bike got dirty but it was also cleaned after most rides. Despite this, the bearings still spin as smoothly as the day the wheels arrived. The end caps on the front wheel use a well-fitting seal to not only protect bearings but also to secure the caps in the hub. Again, this is a nice touch and balances function and form.

The wheels use 32 Sapim double butted spokes front and rear and are genuinely “tubeless ready”, in that they come pre-taped and the valves are provided. The wheels also come with spare spokes for each of the sizes used.

Performance

Initially, when riding the wheels, I found them to be very stiff. Comfort sometimes can be overlooked, especially in wheels. That being said, it is subject to a myriad of different factors - weight, bike, setup, location etc. I do find though, that wheels can come too highly strung from the factory.

It’s a bit of a thankless task for wheel builders, I suppose. If they go too low then it can deliver a vague sensation to the rider and even lose tension over time. Too tight and comfort and deflection can be a real issue. That’s also not to mention how spoke tension will work inversely to tire pressure, which is impossible for them to predict. I do tend to run my bike's suspension very firm, which may not have helped. Essentially, when a tire tracks the terrain it’s sending information to the rim, spokes and subsequently axle. If there is too much tension there, sharp spikes in compression don’t have their edges taken off and it’s all loaded through the axle and I think it can overwhelm the fork - giving a very unsettled and fatiguing the rider. You can have the best suspension setup in the world, but if the information that is being passed on is predominantly large spikes of force then it won’t feel very good.


They did ride well on softer terrain, and if you wanted to put large amounts of side load through the back of the bike, the stiff platform meant you could really carve into things.

Now outfitted with the information with how the wheels rode on softer terrain, I went to do some back to back setup changes on a trail that’s particularly rough and demands a lot from both body and bike. After several runs I found my ideal setup to be with half a turn of tension removed from the front and a quarter from the rear. Sadly, where I was living, I didn’t have access to a spoke-tension gauge so this is hard for me to quantify. With this amendment, it transformed the wheels and I got them to a place where I found them to be very comfortable and offer a vastly improved performance. I think the rim is adequately stiff to enable it to do most of the heavy lifting in terms of lateral stiffness and support. This is good news as it allows you to fine-tune the spoke tension to suit the rider and strike a balance between compliance and stiffness.

I spoke to Alan Graham regarding this issue and he explained that the wheels I received were tensioned to 130KGF, as opposed to the 120KGF standard. He went onto explain that knowing that the wheels were going to be bashed into goodness-knows-what over a few months they wanted to give me the most suitable tension. When I backed off the tension, I probably went back to the stock tension. For my weight of 83 kg and my riding style of ‘hit things’ this tension seemed a great compromise between stiffness and compliance.

Interestingly, Silt hopes to one day offer custom-tensioned wheels to customers. I’m not quite sure how they will execute this but it sounds like a great idea. As you may have guessed, it’s something I think about when going between wheels and really believe it can have a huge impact on the performance of your bike. As ever, if you’re not sure how, or indeed what to do, then please go and see a trained mechanic before grabbing the mole grips and applying liberal amounts of elbow grease.

Reliability

I was initially given the choice between the alloy or the carbon AM wheels. The carbon, while not ridiculous in the context of other options, are dearer at £800. I felt that the alloy wheelset, which costs less than half, was a better representation of what I would personally buy and would be more relevant to a lot of readers.


Whether or not alloy is more reliable is a contentious subject but it does not tend to fail in such a spectacular manner when it does eventually give up the ghost. That said, alloy rims do respond to impacts in different ways. I think I’m quite realistic with my expectations of a rim and I don’t expect it to come out unscathed if the riding is rough. A recent Pinkbike poll would suggest that I’m not alone in this outlook.

I suppose in an ideal world, I would have a rim that is impervious damage that is a competitive weight. However, I understand that everything is a compromise. The Silts took some serious knocks over the course of testing and, while the rim is dinged and dented, it never ruined or stopped a ride.

The first impact to damage the rim was solely down to rider error but did leave me concerned for the longevity of the wheels as it happened very soon after I received them, but throughout the test they seemed to hold up well. After two months the Silt AM Alloy wheels still happily keep air pressure and stay in a ridable condition, even if slightly worse-for-wear; this is a vast improvement over my previous rear rim from another company that lasted less than a month before it wouldn’t hold air. By that comparison, the Silts robustness seems very reasonable.

I expect some people may be horrified at my short expectations of wheels but I really want to emphasise how rocky and flat-out horrible some of the trails were. Great to ride but they were nothing short of abusive to wheels. In other places, this wouldn’t be a concern. Some rims are made of cheese, and I think it would be very unfair to level that accusation at the Silt AMs. After all, most things will break if you hit them hard enough - it all comes down to what's a reasonable expectation.

Once I reach a certain threshold of impact resistance, my next concern is how they react to impacts. Do they fail straight away? Crack? Lose air? Make seating tires impossible in the future? Even though the Silt rim did take something of a beating, I would never say it failed. Even at its worst, with 3 dings in it, seating tires was never too much of an issue. I believe this was helped by the ramped profile of the bead.

As mentioned the internals stayed smooth and drag-free for the duration of the test. One small quirk, however, was the freehub would come loose when I took out my rear axle. This was quite annoying, especially as I was taking my wheel off every day during a tire comparison. I initially was torquing it with the cone spanner, but after a few times I realised finger-tight was just as effective (or maybe as ineffective). This, in a way, meant that it became a minor issue. It wouldn't become loose during a ride, only when I removed the axle. If ever I forgot to check, the leaf spring would ensure that the gears didn’t slip, even if the shifting was inconsistent. I’m loathed to put thread lock on fine threads or unknown alloys so I left it as it was. It was an irritant though. I tried to reduce friction on the axle by regularly cleaning it and applying fresh grease. This helped but only in the immediate short term.

I spoke to Silt regarding this issue and they explained that this can be remedied with a small drop of thread lock. They also added that they now include this step for all of their wheels in production.

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