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Discussion Starter · #1 ·
Hello all,

I'm looking for a cyclocross bike as a "do everything my road bike can't do" option. I mean gravel, light trails, beginning / end of season riding and also a bit of light touring. Hence I need eyelets for racks and fenders and clearance for fat tires.
My main problem is that I'm 5'4 with a 77cm inseam, which means I will have to make a compromise. If you had to chose between:

1) too long a frame
2) toe overlap
3) too small a head angle

..which compromise would you chose?

For my road bike, I chose number 2. But I am told that for touring and riding in mud, I may have to turn the bar more and it may become a problem. I was also told that 650s were a bad idea because of limited wheel and tire options, as well as tubes eventually while touring (but maybe 26' would work better? :confused: ). Of course, the closer the handling can be to that of my road bike, the better.

That sums it up. I'm hoping you can help me so that I can make a better choice with the (few) bikes that are out there for people my size :)
Thank you for any comments / suggestions that you can make

S

Sorry about the double post, I wasn't quite sure where to post this..
 

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poor choices...

Is your cycling inseam only 77cm, which would translate to about a 67cm saddle height? If so, you've got short legs and a long torso. Your inseam is 6cm less than mine and your height is about 7cm less.

I don't get your "choices". You shouldn't even be able to straddle a frame that is very much too long. Toe overlap is mostly a non-issue. It's a fact of life with a smaller frame. Unless most of your riding is figure eights at 10 mph, it should not be a problem.

I don't understand the comment about head tube angle. Small frames most often have a slack head tube angle to help increase the front-center and wheelbase. A larger fork rake is then used to reduce the trail. Both work to reduce toe overlap.

Seems to me that a sloping TT frame would be a must, to help with the short legs. You may need to invest in a custom. There are plenty of good custom builders who could fix you up.

One of the problems with a typical cyclocross bike is the high bottom bracket, that increases the standover height. It still looks like a 44cm Redline would fit. The 52.2cm TT should be plenty short enough with a 73 degree STA.

http://www.redlinebicycles.com/adultbikes/2006-RLADULT-specs_files/spec-geometry-all.htm
 

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C-40 is right. toe overlap is a non-issue. You don't necessarily have to go compact or sloping -- your height and inseam is pretty traditionally within the realm of 460-500 mm frames.
 

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Discussion Starter · #4 ·
Hi C40,

Actually, I have always been told by fitters that I have a short torso compared to my legs. I can straddle all cross bikes I have come accross with at least 2cm to spare (traditional frames, not compact), but they are often too long. I need a top tube of roughly 51,5 cm, which I have on my road bike, but fenders + fat tires need too much clearance for that to be possible without toe overlap / small head angle. The small head angle reduces or even eliminates the toe overlap, but I am told the handling then becomes very slow. I never tried anything under 72 degrees, so I have no idea how problematic that is.

With my road bike, toe overlap is a non-issue. I'm glad to hear that you think it of no importance fo a cross bike too, because I would very much like to come as close as possible to my road bike. I just hope it's not dangerous when loaded and thus riding slower, or on muddy terrain.

If this is the compromise I'm going to make, then I'm left with 4 choices (the Redline unfortunately is not available here in Canada). It's either the Trek X01, the Jamis Nova, the Specialized Tricross (smallest head angle - 70.5 - , but maybe the only one without toe overlap), or custom. Any advice on those is also welcome :)

Thanks for comments, and please keep it coming!

S




I don't understand the comment about head tube angle. Small frames most often have a slack head tube angle to help increase the front-center and wheelbase. A larger fork rake is then used to reduce the trail. Both work to reduce toe overlap.

Seems to me that a sloping TT frame would be a must, to help with the short legs. You may need to invest in a custom. There are plenty of good custom builders who could fix you up.

One of the problems with a typical cyclocross bike is the high bottom bracket, that increases the standover height. It still looks like a 44cm Redline would fit. The 52.2cm TT should be plenty short enough with a 73 degree STA.

http://www.redlinebicycles.com/adultbikes/2006-RLADULT-specs_files/spec-geometry-all.htm[/QUOTE]
 

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sure about that inseam???

If fitters have told you that you have a short torso, then you have not quoted a cycling inseam, or your fitters don't understand torso length relative to height. I've got a short torso at 169cm tall with an 83cm inseam and 72cm saddle height, but I have no problem fitting on most stock frames. You didn't mention your actual saddle height (BB to top of saddle along the center of the seat tube). That would probably tell me more than an inseam mesurement that's not accurate.

It would also be meaningful if you posted the dimensions of the bike youride now, it you think it fits well. The important dimensions are the TT length, seat tube angle and head tube length (with the headset). Mistakes are often made comparing the HTL on frames with conventional headsets to integrated headsets.

You concerns about the HTA are unfounded, IMO. If you look at many Italian road bike geometry charts, you'll find a 71.5 degree STA to be common in the smallest sizes. Trail, which is what affects the steering speed, can be adjusted to some extent with fork offset. The formula for trail is R/tanH - offset/sinH. This tells you that fork offset always reduces trail and the more offset the less trail. As an example, a 71.5 HTA combined with a 50mm offset only has a 60mm trail. A larger (slower) 62mm of trail is produced with a 72 degree STA and 45mm offset.

If you have a problem with too much reach, just changing to short reach handlebars can make more difference than a smaller frame. I use Salso Poco bars, that have a reach that is 1-1.5cm shorter than anything else on the market. I also use a 120mm stem with them, so I could easily switch to a more standard reach with a 105-110mm stem. I actually like the shorter reach, since it positions the straight part of the bars further out for more knee clearance when standing and I like the position while climbing seated with my hands on the top section.

The smallest Trek has a standover height of 76.4cm. Your inseam better be more than 77cm if you ride this bike.

http://www2.trekbikes.com/bikes/bike.php?bikeid=1494000&f=9

The Jamis Nova in the smallest size should fit pretty well.

http://www.jamisbikes.com/bikes/06_nova.html

The smallest Specialized Tricross should also fit, but notice the steeper 75 degree STA, which increases the reach, but only about 5mm.
 

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Discussion Starter · #6 ·
Thank you for your insight C-40.

Unfortunately, I don't know my saddle height and don't have my bike back yet to measure it (long story, was destroyed along with my knee end of last season, insurance getting me the same one back but not until another couple of weeks). My inseem is measured barefoot floor to crotch. I've been fitted by 3 different bike shops and a manufacturer in the past years, and they all said I had a short torso compared to my legs :confused:

My road bike is a LS Bella, TT 51.5cm, STA 74.5, HTA 72, HTL 10cm.
I have an 80mm stem on it and a short reach ITM Elle (70mm reach, 136 bar drop). So it's difficult to shorten reach any further.
I have no idea what fork offset is. Is it the degree to which the fork bends forward? If so, what should I be looking for with for example the Specialized, which has a HTA of 70.5, to make it comparable to a 72 on the Bella? Can I find out what the fork offset is on those 2 bikes somewhere? Or is it something I can adjust myself by swapping the fork? Pardon my ignorance, first time I've come across this issue.

Hope this helps you help me. Thanks again!

S


C-40 said:
If fitters have told you that you have a short torso, then you have not quoted a cycling inseam, or your fitters don't understand torso length relative to height. I've got a short torso at 169cm tall with an 83cm inseam and 72cm saddle height, but I have no problem fitting on most stock frames. You didn't mention your actual saddle height (BB to top of saddle along the center of the seat tube). That would probably tell me more than an inseam mesurement that's not accurate.

It would also be meaningful if you posted the dimensions of the bike youride now, it you think it fits well. The important dimensions are the TT length, seat tube angle and head tube length (with the headset). Mistakes are often made comparing the HTL on frames with conventional headsets to integrated headsets.

You concerns about the HTA are unfounded, IMO. If you look at many Italian road bike geometry charts, you'll find a 71.5 degree STA to be common in the smallest sizes. Trail, which is what affects the steering speed, can be adjusted to some extent with fork offset. The formula for trail is R/tanH - offset/sinH. This tells you that fork offset always reduces trail and the more offset the less trail. As an example, a 71.5 HTA combined with a 50mm offset only has a 60mm trail. A larger (slower) 62mm of trail is produced with a 72 degree STA and 45mm offset.

If you have a problem with too much reach, just changing to short reach handlebars can make more difference than a smaller frame. I use Salso Poco bars, that have a reach that is 1-1.5cm shorter than anything else on the market. I also use a 120mm stem with them, so I could easily switch to a more standard reach with a 105-110mm stem. I actually like the shorter reach, since it positions the straight part of the bars further out for more knee clearance when standing and I like the position while climbing seated with my hands on the top section.
 

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The measurements don't sound too far out of whack to me. Your inseam would put you on a 51 or 53 cm Heron Touring or Wayfarer. Both use 26" (559 mm BSD) wheels in these sizes. If you look at the geometry specs, you'll see that the top tubes might seem a little long for you. However, these frames have taller forks and head tubes. This raises the bars relative to the saddle which has the effect of reducing the reach to the bars. So, Herons will typically fit like the top tube is actually 1 cm or so shorter. In addition, the Heron geometry seems to work well with shorter stems, 8-12 cm, while most other road frames today seem to be offered with 10-13 cm stems.

By the way, the reason that Specialized and some other companies offer such a shallow head tube angle is so they can use 700c wheels while minimizing toe overlap. This is not as much an issue with 26" wheels. Also, look at seat angle. Many small frames use a steep seat angle. This gives you a shorter top tube specification, but in practice, you will have to move your saddle back further on its rail to get the proper position relative to the crank.

For example, your current bike has a seat tube angle of 74.5 degrees, and the 51 or 53 cm Heron has a seat tube angle of 73 degrees. This creates a difference of 1-1.5 cm in effective top tube length. The 53 Wayfarer has a top tube length of 54.5 cm, but it will fit like a 53 cm top tube on a bike with a 74.5 degree seat tube angle. Subtract the 1 cm effect of the taller head tube, and you will find that the top tube of the 53 cm Wayfarer will fit like a 52 top tube on your current bike.

It gets complex, but you need to be aware of how the different frame specifications will affect how a bicycle will fit. Unfortunately, it's often hard to find a local shop that understands all of the issues. Even some of the manufacturers appear to miss the boat. I hope that this has helped shed some light on the issue.
 

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about short torsos....

Comparing your frame dimensions to mine, my STA is the same 74.5 and my TT is only 1cm longer. In addition to my TT being 1cm longer, I use a 4cm longer stem, so my reach is about 5cm longer.

If you're really 162.5cm tall, that's only 6.5cm shorter than me and based on your reported inseam of 77cm, nearly all of the difference is in your short legs, since my inseam is 83cm. Any fitter who knows what he's doing measures cycling inseam to saddle-like crotch contact in bare feet. Saddle-like means very firm, but obviously not enough to lift your heels off the floor.

Saddle fore/aft position can have a major effect on reach. If you happen to have proportionately long upper legs, perhaps your saddle is pushed pretty far back to get your knee over the pedal.

Perhaps you have short arms which makes for a short reach and the short torso comments. There's also the chance that the reach that you find comfortable is just not very long. I ride with a pretty racey fit, with the bars 9cm lower than my saddle. I have enough stem length that I never have any knee to arm interference, even when pedaling in the drops, with my back quite low.

As for fork offset (or rake), here's a picture that will explain it. According the the geometry chart that I have on the Specialized, it has a 71 HTA and 49mm of fork offset. It will have a trail of about 66mm with a 700 x 32 tire. FWIW, that's less trail than a racing frame like a Colnago C-50 would have in asimilar size.
 

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Discussion Starter · #9 ·
Thank you Todd, that makes a lot of sense.
I looked at the geometry for the Heron Touring, and I think the 51 would fit me. I totally agree on the STA issue, and this is the first time I see a small frame with a 73 degree angle! This should help me shorten my reach compared to the usual 74s where I have to push the saddle back. My "ideal" top tube length is 51 (except that's very hard to find), but as you said, taller head tube + normal seat angle should get me there. Can you evaluate if I would need to put 26" wheels to clear the toes or if 700s are possible without overlap? Do you know if there are any dealers in Canada? I'm in Montreal, Quebec. My only concern would be about the long wheelbase of a touring frame vs a cross, as I will never load it too heavily (I will put maybe 20 pounds on it), and so wanted something that was still quick handling. But I think the better fit beats that concern.
Thanks for your input, your explanations are cristal clear.
S



By the way, the reason that Specialized and some other companies offer such a shallow head tube angle is so they can use 700c wheels while minimizing toe overlap. This is not as much an issue with 26" wheels. Also, look at seat angle. Many small frames use a steep seat angle. This gives you a shorter top tube specification, but in practice, you will have to move your saddle back further on its rail to get the proper position relative to the crank.
 

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Discussion Starter · #10 ·
I don't know if it's short arms, personal comfort or women specific positioning. The only 2 other riders my size that I know have in seems of 73 and 74cm respectively, so I assumed it was leg / torso proportion like I was told before, but maybe I'm wrong. The bottom line is that I have more trouble finding top tubes that are short enough rather than low enough for me.

To answer your questions, my saddle is usually set back just a little, but I think that is due to the seat angle. With a 73 degree STA, it would probably be centered. I ride with the bars higher than you, about 5cm lower than the saddle, but on the cross bike it will be even higher than that, as I will be doing some light touring on it. It will probably be almost level.

Thank you for the graph on the fork offset and for the info on the Specialized Tricross. Can I ask you where to look for this info? I can't find it in the geometry tables I have. For the Specialized Tricross for example, the table I have gives me HTA of 70.5 and trail of 69cm. What does that trail measure mean?

Thanks again,

S
 

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rake and trail info...

I found the spedialized tricross info with a google search.

Here's some canned info I keep around on rake and trail. Hopefully, some of the links at the end still work.


Rake is the perpendicular distance between two parallel lines, one through the center of the hub, and one through the center of the steering tube. Trail is the horizontal distance between the tire contact point and a line through the steering axis. The more trail, the more stable the bike (slower steering). The less trail, the quicker the steering. Both rake and head tube angle affect the amount of trail. Steepening the head tube angle or increasing rake will decrease trail, reducing stability and quickening the steering. The formula for trail is as follows, where R is the tire radius, and H is the head tube angle. Trail = (R/ tan H) – (rake/sin H). As an example if R = 33.65cm, H=73, and rake is 4.0cm, trail = 33.65/tan73 – 4.0/sin73. This calculates to 6.1cm or 2.4 inches.

http://kogswell.com/trail.php
http://www.phred.org/~josh/bike/trail.html
http://www.kreuzotter.de/english/elenk.htm
 

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Serotonin said:
Do you know if there are any dealers in Canada? I'm in Montreal, Quebec.
I don't have any dealers in Canada at the moment. I can ship direct, but the import duties can be a little stiff when doing a frame at a time at retail. Take a look around at some other brands, too. I know there are some other companies with similar geometry philosophy.

I wouldn't be too worried about the long wheelbase of our tourers. I use my Wayfarer as an everyday bike. Unlike some loaded tourers, it was designed from the start as a multi-purpose bike. While some tourers handle like a school bus when they are unloaded, the Wayfarer will turn in relatively quickly. It's no racer, but we sacrifice a little in fully-loaded stability to make the bike enjoyable to use for other purposes. Another consideration is that the longer wheelbase gives a bit smoother ride (becoming more important to me as I have passed 40 years of age).
 

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Discussion Starter · #14 ·
C-40, that trail calculator is now in my favorites. Thanks tons. It enabled me to figure out that in the available off the rack choices, the Jamis Nova would be the one to come closer to my LS in terms of trail (actually the Surly Crosscheck comes even closer, but unfortunately not available in Quebec, and the STA is even bigger than other small sizes).

This really helped me: it turns out the Specialized, which has the smallest HTA, actually has less trail than the Trek!
Now I will try to see if I can get it built by my friends at Marinoni with 26'' wheels at a reasonable price. They say they usually never allow for toe overlap, so 700s wouldn't do, but maybe if I sign a discharge.. I really don't want to feel like I am lying down on my bike.
If that doesn't work, I think I am ordering myself a Jamis Nova, unless I can find a Heron dealer close by.

Thanks again for all the great info.

S
 

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Discussion Starter · #15 ·
Thank you very much Todd.
I will look at the options that are available here in Canada. I have to say I have not seen anything with 26'' wheels on the bikes that are available to me, and I see 75 degrees STA more often than not. I sincerely like the geometry of the Heron. Geometry is all I have to rely on, because the market is so non-existant in my size that there is no hope of test-riding anything.
I will also look at the custom option. That may be too expensive for me. So I may send you a message to find out more about those import duties eventually.
Thank you again for a thorough explanation.
S


HeronTodd said:
I don't have any dealers in Canada at the moment. I can ship direct, but the import duties can be a little stiff when doing a frame at a time at retail. Take a look around at some other brands, too. I know there are some other companies with similar geometry philosophy.

I wouldn't be too worried about the long wheelbase of our tourers. I use my Wayfarer as an everyday bike. Unlike some loaded tourers, it was designed from the start as a multi-purpose bike. While some tourers handle like a school bus when they are unloaded, the Wayfarer will turn in relatively quickly. It's no racer, but we sacrifice a little in fully-loaded stability to make the bike enjoyable to use for other purposes. Another consideration is that the longer wheelbase gives a bit smoother ride (becoming more important to me as I have passed 40 years of age).
 
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