Wheel size vs speed vs ride quality

Recumbents and all feet forward machines

Wheel size vs speed vs ride quality

Postby Cyclaholic » Sun May 25, 2008 6:51 pm

G'day everyone,

I just put a Toscana 2026 on order, it's a lot like Europa's except with a 20" front wheel (and blue not red, so not as fast :lol: ) but I'm a bit worried about a few things.

How does the smaller front wheel impact speed and comfort? and to what extent?... I also ride a Cannondale CAAD9 on 23's at 130psi, its about as stiff and harsh a ride as anything but I really like the stiffness and harshness! I can just about read brail with my arse if I ran over it on that bike. But I'm hoping to get my average speed up as I develop my 'bent legs. Is the 20" wheel going to be slower than say a 26/26?

I'm just trying to figure out what to expect, and really, how suitable the Toscana will be for my commuting. My commute is from Ultimo to Wetherill Park (about 50km) I usually go through Marrickville down to the Cooks River cycleway, up to homebush olympic site, then under the M4 to Parra, and down the railway line to Fairfield.

I get the train in the mornings so I'm not buggered all day, which is OK because I travel just outside of peak hour. Anyone else here ever take their 'bent on the train in Sydney? ever have any issues, like with the extra length, etc? I imagine you must get some reactions!

Being an engineer and a DIY tinkerer, I really like the idea of building a rear fairing to encase the panniers and improve the aerodynamics, would it be worth the effort?

Anyhow, lots to think about... looking forward to chatting with you fellers about all things 'bent, maybe hook up for a group ride 8)

Cheers,
Gab.
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by BNA » Sun May 25, 2008 9:04 pm

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Postby Kalgrm » Sun May 25, 2008 9:04 pm

G'day Gab,

Welcome to the forum. I saw your post over on BROL and wondered if you'd link up here too. Seems you did. :)

I can't answer your specific question about the 20" vs the 26" wheel, but I can say that when I put 700c wheels (23mm) onto my Bacchetta Giro 26 after running 26 x1.25 MTB slicks, I noticed an immediate increase in speed (or lower rolling resistance for a given speed) and a much smoother ride. I ran both sets of tyres at 110psi, so the main difference was the diameter of the wheels. So, bigger wheels should give you a smoother ride for a given tyre pressure.

Of course, you don't need to run the same tyre pressures, so you might find your ride is smoother and faster with lower pressures on the front (small) wheel. Lower pressure (to a point) gives you lower rolling resistance.

You can indeed improve your aerodynamics with a tail fairing. It will come at the expense of a little extra weight to pull up hills, so wait until you've been riding for a while before you decide if your speeds justify the need for better aerodynamics. If your average rolling speed is less than (say) 25km/h, there's probably no good reason to build it.

I live in Perth and don't catch the train, so I can help you with the other questions.

Cheers,
Graeme
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Postby Hotdog » Mon May 26, 2008 12:43 am

Hi Gab,

I've taken my Bacchetta Giro 26 on the train in Sydney quite a few times, mostly to get to or from a group ride with Bike North but occasionally for logistical reasons (taking my bike to/from the LBS, or ferrying bike + more stuff than I can carry on the bike between my place and my girlfriend's). Mostly it's been on the weekend, but some of the logistical missions have been during the week and even in peak hour, but never in the peak direction... It's not really any different from taking any other bike on the train once you get used to manhandling the 'bent, you do need marginally more space but if there's enough room in the carriage for an upright bike you should mange to get an SWB 'bent in instead. I have found myself having some pleasant chats on the train with people who asked about the bike, but more frequently my big bright yellow recumbent would fail to generate any more interest than a bemused glance or two (weekend train passengers were more cheerful and chattier than weekday train passengers, I found).

Without having the same person ride the Toscana 2626 and the 2026 to do a comparison it's hard to say anything definitive about the effect the 20" front wheel will have on your new bike's speed and comfort. The smaller wheel won't smooth out the bumps as well, but on the other hand will make it less of a stretch to get your feet to the ground when stopping and back up to the pedals when starting so in that respect it'll be more comfortable than a 26" front would. Other things being equal you'd expect the 26/26 to be slightly faster than the 20/26 due to both rolling resistance and aerodynamic effects, but I'd be surpised if it was a dramatic difference.

Coincidentally, I rode the Cooks River cyclepath from Olympic Park to Marrickville and back this morning with an OzHPV group ride. There's some very bumpy bits in places, you may find you want fairly wide, low pressure tyres if you're riding the Toscana along it on a regular basis. A harsh ride on an upright is one thing, you can easily get out of the saddle on the really bumpy bits and soak up the impacts with your legs and arms, but with a recumbent you're more reliant on the seat, frame and (most of all) tyres for cushioning.

As an aside on your homebrew tail fairing plan, if you're feeling ambitious I'd suggest building a tail box with integral storage space rather than simply enclosing conventional racks and panniers. More effort to design and build, but a lighter, more elegant solution. Try looking at the beautiful (and expensive!) carbon fibre tailboxes made by M5 for inspiration.
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