Cycling UK Forum

I have a close tolerance frame built to accommodate sprints. Now in my late seventies I no longer have a need for such a set up but, although built for speed, it has a relaxed seat tube angle of 71 degrees which is ideal for my physique and leisure riding I now undertake. What it does not have and what I need, however, is mudguard clearance.

To achieve this I am considering the use of a 25-559 to 35-559 wheel-set. From what I can gather these have an approximate tyre diameter of 621 & 634mm respectively as against approximately 676mm for sprints. If correct, their use will result in an increase in frame clearance of circa 21 to 27mm.

However, is this practical? Will the pedals ground when cornering using 170mm cranks? Are there side pull or dual pivot brakes available with an adequate drop?

Approximate frame geometry is: wheel hub centre to bottom bracket centre 60mm. Wheel hub centre to centre of brake pivot bolt 360mm.

Cyril

I think you could do what you propose but the brakes would have to be very long, and like you say, you would lose a fair bit of ground clearance.

You might be better off looking at 584 or even 590 rims. Both sizes were originally meant for a specific tyre width but now have different tyre widths available that fit OK. For example you can buy 28-590 tyres and these will create wheels of around 650mm overall diameter. Similarly a 32-584 tyre will be about the same size.

You'll lose a few mm of ground clearance but this is unavoidable if you want proper mudguards. The ground clearance loss will be less bad than it might at first seem because the wider tyres will actually hold the bike higher up at the same lean angle (if you see what I mean).

There isn't much choice in rims and/or tyres in those sizes but there is some rather than none. You can get 36h aluminium rims in 590 size, and decent (puncture resistant) tyres too.

590 rims would require brakes with 16mm extra drop to them, and I'd guess this would mean a little over 60mm brake drop if it was ~45mm originally. I think you should be able to find calipers of that reach OK . If you go with 584s and rim brakes then I'd suggest that centre-pulls are the way to go.

If the brakes are putting you off, you could think about fitting drum brakes instead. Sturmey Archer aluminium hub brakes are quite nice, an X-FD front and an X-RD rear (for a screw threaded freewheel) would do the trick; they would add about a pound or more to the weight of the machine though.

hth

cheers

Personally I'd stick with the wheels and set up that you have ... my winter bike, an elderly Dawes Mirage had no clearance for mudguards so I did this : http://www.beewee.org.uk/generaldocs/br ... ngs-10.pdf - works fine although the rear brake gets a bit mucky.

Rob

I fitted these to my lose clearance Argos, expensive I guess but beautifully made and work perfectly.

http://road.cc/content/review/95213-pdw ... al-fenders

Rob - what thickness is the steel strip that you used?

robgul wrote:Personally I'd stick with the wheels and set up that you have ... my winter bike, an elderly Dawes Mirage had no clearance for mudguards so I did this : http://www.beewee.org.uk/generaldocs/br ... ngs-10.pdf - works fine although the rear brake gets a bit mucky.

Rob

Many thanks for your interest and prompt reply. Well worth closer consideration which I am in the process of doing.

Regards,

Cyril

Vetus Ossa wrote:I fitted these to my lose clearance Argos, expensive I guess but beautifully made and work perfectly.

http://road.cc/content/review/95213-pdw ... al-fenders

Many thanks for bringing these to my attention. Fitting a bit difficult to visualise but will consider further.

Regards,

Cyril

Hi

I apologise for being nosey, what is your bike?

71 deg seat-tube and close clearance/sprints seems to be an unusual combination

Regards
tim-b

Si wrote:Rob - what thickness is the steel strip that you used?

It's stainless steel, about 2mm thick, 15mm wide and then cut to length after bending to shape using an engineer's vice and hammer - it's actually the stay from a UPVC window frame casement that one of my neighbours was having replaced!

[I made a prototype using a bit of alloy tube that I happened to have flattened out - the concept worked but the material was weak at the bends, hence the steel strip for the final product]

Rob

Thanks, Rob. I tried using some old steel I found in the shed, but must have been too thin as it fractured after a while. Then tried with one of those old lamp brackets....can't see that fracturing but took a bit of bending!

Try the new Ass Saver from edinburghbicyle.com as are planning to use the broad mountain bike version, a simple plastic sheet that clips to the saddle rails. As for 590 tyres use the Schwalbe Marathon Plus Evo wheelchait tyre in 25-590 for three plus years on the rear of my bike with no problem. You can also get this tyre in a 25-559 size as well, both are black not grey tyres.