Frame Size Question

weaselman

Hi, this is my first time posting but I've been lurking on the cycling forum for about a year now. I've just got back on the bike after a ten year sabbitical and I enjoy being on the bike more now than I did when I was younger. I have to say that the information given on this forum is the best of any that I've been trawling through, whether its training, equipment, or even opinions on the pro scene and has helped me in getting back on the bike again. So I'm hoping that someone can help me with a frame size question.

I'm looking at buying a Specialized Tricross Triple and I'm not sure whether to pony up for a 52 or 54cm frame. I will be using the bike for commuting, sportives, fully-laden touring and also looking for something relatively cheap. I'd like to do a one/two month tour next summer and the tricross seems to tick all the boxes. The Tricross with racks, panniers, lights etc comes in just under my budget of 1500. At the moment I have a 15 year old Giant Kronos that is still plodding along and has a 54cm seat tube and 54 cm top tube. The stem is 100mm and is set at a -17 degree angle. My inseam is 30.5 inches (77cm) and I'm 5'6 (167cm).

I've been looking at the geometry over on the specialized site as well but to be honest trying to figure out the best frame size from it would require a degree in maths:
http://www.specialized.com/us/en/bc/SBCBkModel.jsp?spid=38443&eid=123&menuItemId=0

From checking a few forums most riders that use the bike for touring tend to go for a slightly lower frame size than on a road bike to give a more upright position suitable to touring. Regarding the handlebars, they would be coming upwards and closer than I have on the Giant because the angle of the stem is 0 degrees on Specialized bikes and I could get get a 120 stem to lengthen the bars further from the saddle if needed. A 54 frame would probably be more suitable to sportives though. Trying to figure out the right frame size is a bit difficult because I'm not sure if the sloping top-tube affects the the frame size that much. Does the 2cm make a massive difference, or have I missed something?

I know that there are a few Specialized dealers in Dublin but due to one reason or another I haven't been able to get into the shops to try one out for size so I'm just trying to narrow the options down to one of the sizes. Thanks in advance for any advice.

Lumen

Going a size down for racing makes sense, since you want a low, aero position.

Going a size down for touring makes no sense at all. You shorten the reach but also the head tube, which shifts weight forward on to your arms and can cause neck strain from hyperextending the neck (unless you use loads of spacers or a riser stem, which looks hideous). If you want a frame for touring, buy a touring frame.

Size a frame by horizontal equivalent top tube length. Alternatively consult the manufacturers size chart for your height. Whichever approach you take, you may end up tweaking the fit with a different length stem, but if helps to be as close as possible to avoid freakishly short or long stems which affect the handling and weight distribution.

There are loads of generic sizing charts around, like this. It's all voodoo really, you can't really fit a bike properly except in person.

weaselman

Thanks Lumen. You mentioned two things I hadn't even thought about. I didn't think the stem length would affect handling but it seems obvious the more I think about it. Also, I hadn't thought about my neck coming into the equation and the shift of body weight.

I managed to find a few size charts for my height and it looks like a 54 would be the right size. I'll do a round of the bike shops next weekend see if i can take a few for a test ride. I was looking at a few different bikes such as Dawes Galaxy, Surly LHT and Koga Traveller (not really an option due to price, have to keep under budget). I really like the look of the Tricross and had read on a few touring forums of people using them for touring. I might be caught it the trap of looks trumps practicality.

weaselman

Just read through the link you posted, some interesting stuff in there. Thanks again Lumen

petethedrummer

Looks like you're on the border of a 52 and 54 from this link:
http://www.cyclestore.co.uk/contentPages.asp?pageID=62

And this though it doesn't say anything specific for the Tricross:
http://www.stonehengecycles.com/page/62/spec_bike_sizing_guide

So I'd try both and see which feels better.

Lumen

weaselman wrote: »

I really like the look of the Tricross and had read on a few touring forums of people using them for touring. I might be caught it the trap of looks trumps practicality.

The Tricross is a cyclocross bike, therefore will have a more relaxed geometry than a proper road bike. This means longer head tube (or at least a riser stem IIRC), a shorter top tube and longer chainstays. It also has clearance for mudguards. Therefore, it's not a terrible choice for touring, and probably cheaper than many touring bikes.

The problem with using a cross bike on the road is that whilst cantilever brakes can be adjusted to give decent stopping power, they will never work as well as calliper brakes, and can be a bit of a bitch to set up with drop bar levers.

weaselman

I think its going to be a bit like clothes shopping so, always trying to find those in-between sizes . Damn genetics.

I have read on some reviews of the tricross that there is judder when braking on the front. I don't think this will inspire confidence on a fully-loaded machine so I'll have to see what thats like when I get round to road-testing one. If its just too scary I'll begin the search for a touring specific frame. The cost and looks of the tricross were the two initial reason I went for it over a touring frame.

Lumen

weaselman wrote: »

I have read on some reviews of the tricross that there is judder when braking on the front. I don't think this will inspire confidence on a fully-loaded machine so I'll have to see what thats like when I get round to road-testing one. If its just too scary I'll begin the search for a touring specific frame. The cost and looks of the tricross were the two initial reason I went for it over a touring frame.

As I understand it, fork judder on cyclocross bikes is caused by a combination of high braking forces, MTB-style brake mounts (i.e. two mounts one on either fork "arm") and carbon fork construction. For a given amount of braking force, the degree to which judder is an issue is fork-specific.

I did not experience it on my Tricross, which was equipped with mini-v brakes. The original Tricross came with cantilever brakes. Perhaps these were set up with more braking force than the mini-vs, or maybe Spesh beefed up the fork, or maybe I just don't brake hard enough or am too light for it to be an issue.

I'm not sure this brings any clarity!