Rim width, tubeless plugs and quiet freehubs: GCN Tech clinic

Alex Paton and Ollie Bridgewood are back once again in the tech clinic studio to delve into some of your latest bike-related questions. This week they take a look at the effectiveness of tubeless repair plugs as well as finding out when a waxed chain might not be the best solution for lubricating your drivetrain.

Will a wider internal rim width have the effect of widening my tyre width?

The effective measured tyre width when inflated does correspond to the internal rim width of the wheel. The narrower the rim the more rounded the tyre profile has to be in order to sit under the hook of the rim. As the rim width increases the tyre has to form less and less of a rounded profile until it makes more of a ‘u’ shape instead. As this happens the tyre material can sit wider as well meaning that the same tyre can measure wildly different widths purely depending on the rim it is mounted to.

Is plugging a tubeless puncture a suitable long-term solution?

So long as the plugging process is carried out properly a tyre that has been plugged can be used without issue. There are of course some areas of the tyre that make plugging difficult and can lead to issues, such as on the sidewalls of tyres, especially near the rim of the wheel. If repaired well a tubeless tyre can have an unaffected lifespan after being plugged, after a while it can even be hard to pinpoint exactly where the repair is situated.

The type of plug you use can also have a marked difference in the effectiveness of a puncture repair. The most common type of tubeless repair plugs are not best suited to road bikes and work far better with large-volume gravel or mountain bike tyres. Both Alex and Ollie have found that for road bikes, using the Dynaplug repair plugs has yielded the best results.

Can I use two different cassettes with the same chain?

If you are looking to run a partly used cassette on an indoor trainer and run another partly used cassette on your wheels you shouldn’t have any issues. The only time issues will start to come in is when either the cassette or the chain itself has become too worn to properly mesh.

The best and easiest way to prevent this from happening is to routinely check the wear of your bike's chain. To do this you need a simple chain checker that can be bought for a handful of pounds. When the chain has reached the wear limit (typically 0.75mm) replacing the chain will keep both cassettes running without issue.

Can I make my freehub quieter without affecting the efficiency of the bike?

You can make the freehub of the rear wheel quieter by adding slightly thicker grease to the internals of the freehub body. When doing this you don’t want to deviate too far from the intended grease or oil that the manufacturer has approved as it could hinder the performance of the pawls inside.

If you have a ratcheting freehub it is possible to fit a slightly lower tension spring inside the hub. Once again you do not want to deviate too far from the manufacturer spec. However a lighter spring will allow a lighter action between the two ratchet ring resulting in a quieter freehub.

Is there a way to add paraffin oil to a chain wax solution and has it been tested?

When we last had Silca CEO Josh Poertner visit the GCN megabase we got to ask him about different additives to chain wax treatments. He said that by adding one or two drops of the brand's synthetic oil into it would soften the wax and prevent it from setting quite as hard.

The issue is that as soon as you start making the wax coating softer it begins to lose some of the properties associated with it. Adding an oil that would soften the wax would also likely encourage dirt and grit to stick to the chain and could then cause more wear and contamination.

If you do find yourself riding around in wet conditions often, rust can be an issue for a waxed chain. This is because if any moisture does work its way past the barrier the wax creates, then there is no further protection from the chain rusting. If this is something that does affect where you ride, moving to a traditional oil-based lube could actually be the best option.

Is there a way to stop a saddle from squeaking?

Saddles can squeak from a couple of different places, the most common is from the rails of the saddle themselves. If this appears to be happening the first port of call is to make sure that the seat post clamp is torqued up to the correct value. If this does not solve the issue checking the saddle base for any cracks or damage would be the next place to check.

If the squeaking appears to be coming from the saddle itself internally it might be a sign that everything is not okay with it. Saddles should be bonded together to prevent any layers from moving independently of each other. If the saddle has started to squeak some of these layers have likely started to break down.

Saddles do have a life and do deteriorate over time. Depending on how heavy you are and the types of roads you mostly ride will dictate how quickly this happens. One of the most common places for a saddle to break down and fail is in the middle along the length of it. If the saddle looks to have bowed in the middle or can easily be pushed out of shape it might be a case that the saddle needs replacing.

Do sub-zero temperatures affect the qualities of chain waxes?

Chain wax does have an optimal working temperature as it is an amorphous solid this means that the properties it exhibits change with temperature. As the temperature increases the wax will behave more like a liquid and will decrease in viscosity. Equally, as the temperature decreases the wax will behave more like a solid and will offer less efficiency gains as well as worse lubricating properties. If you find yourself riding in sub-zero climates then a wax chain treatment is likely not the best solution.

If you have any tech-related questions that you need answering, head over to this week’s Tech Clinic video on the GCN Tech YouTube channel and add your question to the comments along with #ASKGCNTECH. Or leave your question in the comments below!

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