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-   -   Question about front center/fork rake... (https://www.bikeforums.net/framebuilders/988434-question-about-front-center-fork-rake.html)

SpeedyStein 01-05-15 06:15 PM

Question about front center/fork rake...
 
Hi guys, I have a question that requires bike geometry knowledge far greater than I possess...

I ride a Novara Zealo road bike, size large, which for me is a great bike. The frame is a comfortable fit, the handling characteristics are what I like, and the ride is firm, but still smooth enough for me.

The one and only issue I have with this bike is the fitment of a front fender. It has eyelets in the frame and fork for fenders and racks. The rear fender mounted fine, a little tight, but once on, no undesired effects. The front also mounted without issue, but the only thing is there is a fair amount of toe overlap. I do a lot of urban riding, with lots of traffic, and lots of low speed, high angle turns of the bars. With the bars about 30 degrees from center, the tire itself grazes my shoe - but with a fender, its a lot of overlap. Enough overlap that I no longer feel comfortable riding this bike with a fender.

So, my question:
Short of trading for a different frame, what are my options? I installed a shorter crank, which helped, but is still not enough. I use clipless pedals, so my feet are always in the same place for each rotation. I thought about a new fork, but I haven't been able to find anything with more offset than REI claims. They state that the fork is 404mm axle to crown, 50mm offset.

Would a longer fork designed for a 29er help my situation? I don't want to change the handling too much, especially if it makes the steering faster/twitchier - this bike probably wouldn't lend itself well to that, especially since I am mostly using it for commuting/urban riding and fire road/gravel/light trail riding.

Or should I not bother with changing this bike and get something with a longer front center? I have looked, and honestly, there don't seem to be many drop bar bikes out there that are more than a few mm longer than mine.

For what its worth, I usually ride between a 56-58 size frame, I am 5'11", and wear size 46 shimano shoes. Thanks in advance for any input/suggestions!

79pmooney 01-05-15 06:31 PM

First, do you like where your cleats are mounted? Can you move them closer to your toe and still fell comfortable?

Going to a fork with more rake will help overlap but will make the bike "twitchier", ie quicker steering. 50 mm rake seems to be the industry max these days so finding one with more might be a challenge, but in the true old" days, forks often had far more, combined with more shallow head tube angles. Any custom builder could build you a steel fork with whatever dimensions you wanted and a good one will not let you go to one with poor handling issues. That would cost probably $500+ before paint. (He could also build you a fork for a smaller wheel. THat would be addressing the overlap problem at its source! Of course, you then have two different tires, tubes, etc. on one bike. A challenge very small women have been dealing with for years when they ride bikes that truly fit.)

Ben

Dave Kirk 01-05-15 06:45 PM

First I would look at just how much overlap you have.

Clip your shoe in the pedal (without your foot in it) and turn the bars and cranks until you get to the overlap position. Then take a ruler and get a rough number of how much overlap you have.

Say you have 20 mm of overlap - if that's the case nothing you are going to do with crank length or cleat position is going to make the overlap go away. You'd of course be able to reduce it but with that much you'd run out of travel on everything and still have overlap.

You could of course put a fork in with more rake (assuming you can find something suitable with the right span but longer rake) and that would no doubt help but you will be looking at 5mm or so in gain.

So measure and do the math and see how much you need to move to get it to happen for you.


dave

SpeedyStein 01-05-15 06:48 PM

Hi Ben,
Thanks for the quick response!

My cleats are already pretty much as far forward as the shoe allows. Thanks for the great idea though, I really had my hopes up for a second before I checked!

I was thinking that a custom fork would be the best option... but since I only spent about $700 on the whole bike, $500 is a lot for a fork. I think for that kind of money, I would probably just get an old (think super long 70s frame) road bike off CL.

Any input on a fork with a longer axle to crown length? There are tons of forks with about the same rake available in varying axle to crown measurements - anything from 390 to about 460, but I don't know how much a longer fork would nix the handling/fit of the bike. Obviously something with 460mm axle to crown would change it much more than something with 415, but to what degree would that help with toe overlap, if at all?

Again, thanks for responding!

SpeedyStein 01-05-15 06:53 PM

Hi Dave,
Thanks for responding, and getting me thinking about options. With just the tire, right now it barely grazes the shoe. With the fender as close to the tire as I dare, it is about 15-20mm of overlap. I am beginning to think that I am looking at life without fenders on this bike!

hueyhoolihan 01-05-15 07:24 PM

about half my bikes have toe overlap and none have fenders. i think most people freak out and overreact when they first discover it, but a few slow speed riding sessions in a safe area is usually enough for just about anybody to overcome their fears. IMO, it's not necessary to make any compromises.

it's really just a matter of balance and knowing that it can occur and what needs to be done when it does. it soon becomes intuitive. it's the unpreparedness and immediate sense of an impeding crash that is initially disconcerting.

SpeedyStein 01-05-15 08:43 PM

Hi Huey,
Nice to see a local (to me) post a response - I live in Concord.

The overlap with just the tire isn't what bothers me... without a fender my foot just slides against the tire without causing much trouble. The fender is what gets me though, cause more of my foot catches, and its more likely to stick and cause me to low side.

I come from a MTB background, where this is pretty much never an issue. The only other road bike I had fenders on before this one was an old Raleigh, which had miles of room for whatever I wanted, so it never occurred to me to look into this before buying this bike. I guess since this never happened to me before now, I kinda freaked out when it did the first time. It happened again on the way home that same day, and I took the fenders off that night. I'm sure that you are right, a little practice around the neighborhood would probably help.

All the same though, is this common in modern road bikes, or did I get the lucky bike with a short front center? I can't be the only one with this issue...?

Andrew R Stewart 01-05-15 10:07 PM

The bike must have a pretty short top tube and/or steep head angle/short rake. Generally the larger sized bikes have less toe overlap due to longer front centers. I do agree with Dave K in that you'll only peck away at the overlap with the changes you can easily make.

The first thing I'd look for, if you brought the bike into the shop I work at, would be a bent fork or frame. Then I'd pull out my tape measure and start to measure the geometry. As has been mentioned in other threads a better fitting frame could be the best solution, people that fall off the bell curve of body size/shape can find the cookie cutter geometry not the best fit for their needs and wants. Andy.

SpeedyStein 01-05-15 11:10 PM

Hi Andy,
Thanks for chiming in. It does have a shorter top tube than my old Raleigh, but it is a smaller frame. I opted for the large, because on the test ride it was pretty comfortable, and it has been a comfortable ride ever since. I don't think any of the tubes are bent, since I am the original owner, have never crashed it, and there are no signs of any damage (scratches, dings, ripples, nada). Also, the front disc calipers align perfectly with the rotors - I think they wouldn't align properly if the fork was bent. I think its just a combination of a short top tube and a steep head tube angle. I'm guessing that's probably why they went with a 50mm rake fork too - to increase the wheelbase as much as they could and still have a decent handling bike. That's the funny thing, this bike is a lot of fun, and really comfortable for me. Perhaps a taller person would find it cramped, but they would also probably take the next size up frame.

Thanks everyone for your input and suggestions!

dsaul 01-06-15 07:02 AM

Have you thought about shortening the fender? It won't give as much protection, but its better than no fender in the rain.

randomgear 01-07-15 01:33 AM

Can anything be done to get the fender closer to the tire? That might be one of the easier fixes.

I don't know what length cranks you are using, but shorter cranks would give more clearance, although it may not be good for your bike fit.

Andrew R Stewart 01-07-15 09:21 AM

As to fender mods- Water leaves the tire at a tangent. So draw a tangent (a yard stick is a good device to illustrate with) from the tire's tread to what ever you wish to keep dry. You'll see what will get wet when you cut back a fender and how poor clip on mountain bike fenders are:) Second point is that there should really be about 1cm of clearance between the fender and the tire. While not super common it is very possible to trap a piece of stone (or other road bit) onto the tread and get carried up inside the fender. Without adequate clearance the bit will jam up and cause the tire to stop rotating. This is why many front fenders are coming with a stay disconnect end fitting.

Once again the Op's bike is an example of a less then ideally designed bike. Often this is only realized when one tries to use the bike for other then it's narrowly intended purpose was. Andy.

fietsbob 01-07-15 01:56 PM

Ride Fast ! TCO is only a Problem when making slow speed turns , then realize the wheel is there and keep the pedals away from the 9 and 3 o'clock positions .

6 and 12 , no Problem


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