Tech Clinic: Electronic Gears, TT Chainrings & BOA Cycling Shoes

Your burning bike tech and maintenance questions are answered by the GCN tech crew

Clock20:30, Wednesday 7th February 2024

Alex Paton and Ollie Bridgewood are taking a look over the latest viewers' questions in this Tech Clinic with questions around frame materials, TPU inner tubes and bike fit all on the menu.

I am in my 40s and looking to get a new bike for long endurance rides at a leisurely pace, do I need to spend more and get a carbon fibre bike or will aluminium do the job?

A lot of these questions will come down to preference over anything else, as both a carbon and aluminium bike will be perfectly up to the task at hand. Carbon fibre framed bikes are a little bit lighter and can be a bit more forgiving due to their intrinsic material properties. This does come at a considerable cost though with an equivalent carbon fibre bike costing hundreds if not thousands of pounds more than an aluminium bike.

The areas that are more important than frame material when looking to buy a new bike are things like the maximum tyre clearance as wider tyres will naturally create a more comfortable ride. Above all else the most important thing, especially when looking to buy an endurance road bike is that it is comfortable to ride. Getting a bike fit to get the bike tailored to your body's needs will be worth more than the difference between aluminium and carbon could ever provide.

TPU inner tube deflates overnight but there are no punctures and the valve does not leak air. One time when I was standing next to the bike there was a rapid loss of pressure from the valve, what could I do about this?

The issue here could be with a defective inner tube but it is also worth checking the rest of the wheel, tyre, and tube system to make sure nothing else could have caused the issue. Checking the rim tape around the valve would be a good place to start, ensuring that there are no sharp edges or metal surfaces exposed that could nick or chafe on the tube, causing a rapid loss of pressure.

Something else that Ollie has seen in the past is that if tyres are pumped up close to their limit and then left somewhere near a heat source or direct sunlight the heat can cause the tyre pressure to increase beyond the working limit of the tyre, tube or rim that can cause a rupture in the tube and lead to a rapid loss of pressure. Checking all the tubes that have suffered this issue to find the common cause should help point you in the right direction to hunt down the cause.

Are there any real benefits to having electronic gears?

We get this question sent to us fairly often with a lot of riders aspiring to have a bike equipped with electronic groupsets. The thing to bear in mind is that it is only during shifting there is any difference at all between a mechanical and an electronic groupset. If you are riding in a selected gear using 105 mechanical or 105 Di2 there will be no difference.

The main benefit of electronic over a mechanical group is that there is less maintenance, particularly through the winter. One of the main afflictions with mechanical groupsets is that the actuating cables are susceptible to water and dirt ingress that can make shifting feel slow and sticky. As this is all controlled by wires and motors in an electronic groupset this is not an issue.

For the most part, the difference between electronic and mechanical groupsets is not significant enough to justify the cost solely based on performance alone. One of the main reasons riders choose to use electronic gears is simply for the pleasure of using them.

Should I fit bigger chainrings to my TT bike or should I work on my riding cadence?

Changing your cadence can be a hard thing to do as we typically ride at our body’s preferred cadence naturally. If you do find that you are spinning at under 80rpm it might be worth adding some cadence drills into your training to try and make riding at higher cadence’s that little bit easier.

For the most part, fitting bigger chainrings would be the easier route to go down. The only consideration is based on where you ride and train. Although a bigger chainring will be ideal for race days it could result in your TT becoming unrideable for training.

What is the advantage of using Boa dials on shoes, velcro seems more aero and laces are lighter.

The main advantage of Boa dials is that they are easily adjustable and have added security over other types of shoe closure mechanisms. Unlike laces and velcro, to some extent, Boa dials can be adjusted on the fly simply by reaching down and turning the dial. They also use a material called Dyneema for the lacing that does not stretch, meaning that they feel more secure and do not get looser throughout a ride.

Shifting into the big ring is incredibly stiff but changing down to the small ring is easy. The derailleur is freely moving when moved by hand, what could be the issue?

If you have checked the operation of the derailleur by hand and it is not being restricted by either the limit screws or by a damaged mechanism the most likely and cheapest place to look to is the gear cable itself. If the gear cable has become contaminated with water or dirt the friction between the inner cable and outer housing can make shifting incredibly difficult. Changing up into the big ring will be harder than changing to the small ring as you are also fighting the spring tension in the system.

No matter how I try and configure my bike I always find myself sitting on the nose of the saddle, is there anything I can do to stop this?

The best bet, if you are running into issues like this, is to get booked in for a bike fit. It could be a whole range of potential issues that is causing you to perch on the nose of the saddle and getting a professional bike fit is the best way of finding out what exactly the issue is. It could also be that the shape of your saddle is not right for your body which can be extremely common if you tend to just use the saddle that came fitted to the bike as standard.

Do you have a tech question you want answered? You can leave it under the comments of this YouTube video or in the comments section at the bottom of this article.



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