# Translating Bike fit from One Bike to Another



## 13thcyclist (Jan 23, 2011)

I was wondering, how would I transfer the fit of one bike (in this case, my 55.5cm ST/57cm TT Giant Defy) which fits really well currently; to another, smaller (maybe too small? 54cm TT & ST) sized bike (a Novara Trionfo)? It doesn't help that the sizing between these two is pretty off.. e.g. the Giant has a gigantic headtube, while the Novara has a comparatively tiny headtube (can't hunt up a geo chart for the life of me.. basically, it's this bike but an 80s model w/600 & Dura Ace: BikePedia - 1993 Novara Trionfo Complete Bicycle)

Basically, what kind of measurements should I be taking from the Giant and duplicating onto the Novara? Things like saddle-bar drop, stem + TT length, saddle fore-aft, etc? And how do I factor in the issue of the Novara being a smaller sized bike? I think the Novara actually has a much smaller crank arm length too, 170mm vs 175mm on the Defy.


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## AndrwSwitch (May 28, 2009)

Crank arm length is hard. Different people find they make different adaptations.

To my mind, a reasonable simplification is that the saddle has a certain relationship to the bottom bracket and the handlebars have a certain relationship to the saddle.

You can measure the vertical height of the saddle above the bottom bracket and its horizontal length behind. To be honest, I usually just rough it in by matching the length along the seat tube. Seat angles aren't all the same, which introduces an inaccuracy here. There's not a very good reference point on different saddles, so that's another problem. If you use the same saddle on both bikes, the nose is often recommended; certainly makes sense to me.

I'd probably just eyeball my saddle-bars drop. For reach, I'd use a tape measure.

I'd probably end up doing some tweaking when I rode the bike. I know that some people fit their bikes identically, but since I don't have the same saddles, handlebars, shifters, and uses for all my bikes, I find I get a little variety. Not much, but it's there.

Park Tool actually has a worksheet. It's a lot more extensive than what I've outlined, and should give you a much closer match. Up to you to decide if that's worthwhile.

Park Tool Co. » ParkTool Blog » Road Positioning Chart


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## PJ352 (Dec 5, 2007)

If you were considering going from your relaxed geo road bike to another (similar) road bike, then I think taking some key measurements to establish a baseline would be prudent. But given that (save for saddle height) more is dissimilar here than similar, for a couple of reasons, I'd advise you to start over with a TT bike fit.

First off, rider position is different, so even if you took those key measurements, you'd have to adjust to apply them to your TT bike. Also, odds are that you'll end up tweaking fit anyway, so save the effort of comparing apples to oranges. Second, if you're serious enough to invest in such a specific use bike, I'd think you'd want to maximize both your investment in it and performance on it. After all, a TT bike is all about maximizing performance.

So, my advice is pretty simple. To ensure a fitting will go well take the steps necessary to get sizing right, seek out a suitable TT bike, then head to a reputable fitter.


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## JCavilia (Sep 12, 2005)

PJ352 said:


> If you were considering going from your relaxed geo road bike to another (similar) road bike, then I think taking some key measurements to establish a baseline would be prudent. But given that (save for saddle height) more is dissimilar here than similar, for a couple of reasons, I'd advise you to start over with a TT bike fit.


I think you misunderstood him, if you thought he was talking about going to a time trial bike. The new bike is a regular road bike. "TT" meant "top tube" in his discussion.


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## PJ352 (Dec 5, 2007)

JCavilia said:


> I think you misunderstood him, if you thought he was talking about going to a time trial bike. The new bike is a regular road bike. "TT" meant "top tube" in his discussion.


I think you're right, but it wasn't the reference to TT that threw me off. For some reason, after reading the OP's thread re: why he should (or should not) purchase a time trial bike (in the frame/ fork forum) I made an assumption when reading this thread. Didn't help that Bikepedia's site lacked a pic and listed the Trionfo as road race/ triathlon, but I should have researched further. 

OP: without a geo chart to directly compare to the Giant, the best feedback you're apt to get are general best practices, and IMO Andrew pretty much covered them. If you had physical possession of the bike, more direct measurements/ comparisons could be made, but I still think you'd be looking at either doing a general/ initial fit, tweaking from there or opting for a bike fit. The crank arm length differences may or may not be an issue. 

Bottom line, until you're confident that sizing is right (for you), I suggest holding off on any commitment to purchase.


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## 13thcyclist (Jan 23, 2011)

PJ352 said:


> I think you're right, but it wasn't the reference to TT that threw me off. For some reason, after reading the OP's thread re: why he should (or should not) purchase a time trial bike (in the frame/ fork forum) I made an assumption when reading this thread. Didn't help that Bikepedia's site lacked a pic and listed the Trionfo as road race/ triathlon, but I should have researched further.
> 
> OP: without a geo chart to directly compare to the Giant, the best feedback you're apt to get are general best practices, and IMO Andrew pretty much covered them. If you had physical possession of the bike, more direct measurements/ comparisons could be made, but I still think you'd be looking at either doing a general/ initial fit, tweaking from there or opting for a bike fit. The crank arm length differences may or may not be an issue.
> 
> Bottom line, until you're confident that sizing is right (for you), I suggest holding off on any commitment to purchase.


Hmm, people actually follow my threads? I must be well on my way to being a 'regular' here! 

But yeah, this is unrelated to the TT bike I may or may not get (probably may not, since the TT bike I have in mind [Kestrel Talon] is not even a strictly a 'real' TT bike =\.) To clear things up, the Giant is my traditional 'long rides/group rides/general riding' bike, while the Novara is strictly my 'commuter/beater/rain' bike. Even though I don't intend on commuting for more than 2 or 3 hours on the Novara, it would still be nice to have it fit well on those days where I find myself having to go that far.

For the TT bike issue, I'm thinking I may skip out entirely and stick to my original plan to go for the 'end-all-be-all' upgrade to a Ti bike.


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## onespeedbiker (May 28, 2007)

As a basic setup I would measure from the middle of your seat to the handlebar/seatpost clamp. Then measure the difference in height of your seat and handlebars and try to duplicate both measurements with your new bike.With a shorter the crank the seat will be 5mm higher so just factor that in. Finally lay a level across your seat and see if it's canted one way or another. These are all rough fitting points (especially with the seat cant as seats can be very different) but they will give you a place to start and once on the bike you can tweak to fit.


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## AndrwSwitch (May 28, 2009)

13thcyclist said:


> Hmm, people actually follow my threads? I must be well on my way to being a 'regular' here!
> 
> But yeah, this is unrelated to the TT bike I may or may not get (probably may not, since the TT bike I have in mind [Kestrel Talon] is not even a strictly a 'real' TT bike =\.) To clear things up, the Giant is my traditional 'long rides/group rides/general riding' bike, while the Novara is strictly my 'commuter/beater/rain' bike. Even though I don't intend on commuting for more than 2 or 3 hours on the Novara, it would still be nice to have it fit well on those days where I find myself having to go that far.
> 
> For the TT bike issue, I'm thinking I may skip out entirely and stick to my original plan to go for the 'end-all-be-all' upgrade to a Ti bike.


How is the Kestrel Talon not a real TT bike? It's got a shortish top tube, shortish head tube, steep angles, and ships with an aero bar... Granted, it's not a class of bike I know particularly well.

What does not commuting for more than 2 or 3 hours mean? Each way? In a week?

I've always used my commute bikes for relatively short distances, usually topping out around a half hour. More than that, and I find I want to dress up as a cyclist, wear funny shoes, etc. And then I just ride my nicer bike. Do you not have a secure place to keep it on the other end?

Have you ridden your commute on the Giant yet? (So, is it feasible?) What about riding in the rain? I think it's worth seeing if this stuff is practical for you, and if it's going to be of practical benefit to have a separate bike for it before you buy another one. I've known people who acquired a whole bunch of bikes all at once and then lost interest in riding. I'm not saying that's you. But if it isn't, you have plenty of time to buy bikes. Give yourself some time to really know this one first.


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## 13thcyclist (Jan 23, 2011)

AndrwSwitch said:


> How is the Kestrel Talon not a real TT bike? It's got a shortish top tube, shortish head tube, steep angles, and ships with an aero bar... Granted, it's not a class of bike I know particularly well.
> 
> What does not commuting for more than 2 or 3 hours mean? Each way? In a week?
> 
> ...


A lot of people in the other thread are saying that the Talon is simply a road bike with tri bars slapped on them for the tri version. But I have been researching other forum posts for this bike and there doesn't seem to be much bad to say about it. I even have a friend on my Saturday group rides who rides the road model of the Talon, and he's one of the fastest in the group, so the bike is certainly not holding him back! Seems the only negatives are it is an antiquated design (that bonded rear triangle is.. yuck:frown2, it does not have enough of a TT geo to qualify as a good TT bike (the shallower 76.5deg angle for the 55, etc), and apparently warranty support since Kestrel was acquired by Fuji? But this is getting OT from the original concern, so on to that.

My regular commute, which is to school, is about 7 miles each way. Unfortunately, I live on a small mountain, so it is really 20 minutes downhill going to school and then 40mins to an hour uphill back home, depending on the route I take :mad2:. So yeah, about an hour to hour-20 commute each day (right now, that's more like twice per week since the route is a fair bit dangerous with miniscule shoulders on a main highway, but I'll eventually work up the courage to regularly do the bike commute) I only say I 'may' ride 2-3 hours or more if I have to run an errand in town, which is about a 1-1.5 hour ride one way in.

I have tried to commute on the Giant, and it was all I had to commute on before I bought the Novara. It was pretty terrible, I have to carry a backpack so there was always a small lake of back sweat mapped onto my back. Don't have to worry about that when I can toss it onto the rack on the Novara (I did have the rack on the Giant for a while, but decided it looked ugly enough to buy another entire bike for it ) And I have had enough rain rides on a fenderless bike to know how absolutely horrible a wet back and chamois can feel rrr:.


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## PJ352 (Dec 5, 2007)

13thcyclist said:


> A lot of people in the other thread are saying that the Talon is simply a road bike with tri bars slapped on them for the tri version.


I tend to agree. Save for the shortish HT, if you look at the HT/ ST angles and ETT on the Talon, they're more aligned with a road (race) bike than a TT/ tri bike. But then, this thread isn't about TT/ tri bikes. :wink5:

Re: the comment you made in your other post about going for the 'end-all-be-all' upgrade to a Ti bike, considering the frequency of your 'alternate ideas', I'm skeptical any will be your 'end-all-be-all' bike. More, I see the n+1 philosophy emerging.


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## AndrwSwitch (May 28, 2009)

When I was in college, I was willing to wear my cycling shoes all the time. I had a pair of casual cycling shoes that were less bad to walk in until I wore down the sole and replaced the cleat. Now they're actually worse than my more serious MTB shoes, and I don't know why I don't just throw them out. Now I just wear running shoes, unless I'm going somewhere where I want to be wearing work boots, or I feel like wearing some other shoe. It's nice to be able to where whatever shoe I want and not have to carry a change of shoes with me.

If you do clipless pedals on your "real" rides, you're still going to want them when it's raining. If you're willing to wear clipless pedal shoes all day, or change in and out of them when you do your commute, maybe having the Novara be both a rain bike and a commuter is practical. My solution has been that my nicer bike has fenders for six or seven months a year and my commuter has a rack and fenders full-time, and toe clip pedals so I can wear whatever shoes make sense for the day. My commuter also has a little less saddle-bars drop than I'd use if I rode it without a bag, but I'm sure I could work that out. The shoes are what really kills it for use as a wet weather training bike - on a "real" ride, I want to wear cycling shoes. For commuting and errands, I'd just as soon not.

When I string together a bunch of errands on a bike, it feels very different to me than when I do a continuous ride. I find fitting bikes for errands more forgiving, even if the total ride time ends up the same as one of my shorter road rides. So, no necessity for cycling shoes for errands either.

The point to all this is you need to figure out how you're going to approach your commute rides - are they "real" rides that start and end at different places, and maybe have detours to pick things up on the way home, or are they just transportation? The longer I ride bikes, the more comfortable I am with being a Fred about my transportation bikes. My current commuter is a Portland, and it's probably as Fredly as it's possible to get on a road model with some drop from the saddle to the bars and no aero extensions. I even taped a $7 flashlight to the head tube as a backup for when I didn't anticipate needing my better light, and I typically ride it in jeans and dorky velcro things to keep them out of my drivetrain. On my nicer bikes, sometimes I'm fully into the other end of the Fred spectrum, with my matchy-matchy team shorts and jersey. So that (and that my nicer bike is more expensive and I don't want to lock it outside, and I'm sentimental enough not to want to mess up the paint faster than I already am) puts me on separate bikes.

You're going to have to figure this out on your own to some extent and everyone prioritizes differently. Some people commute like they're trying to win their AG in a tri, and some people put BMX bars on and old mountain bike, sit bolt upright, and ride slower than I run. Obviously everyone who does it differently from me is wrong!  Anyway, I think how athletically you want to approach your commute is going to determine whether you can use your commute bike for anything else.

You're definitely on your way to n+1.  Nothing wrong with that necessarily, but you want to think about whether your bikes are sufficiently good that you want more of them at that level, or if you're adding more bikes that aren't quite right for your use, or need this or that little thing to be perfect. I have a little rule for myself that I always finish any current bike projects before embarking on new ones. So far, it's kept me from having the basement full of half-assembled and non-rideable bikes that some of my friends do.


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## velocanman (Jul 15, 2011)

It was basically covered but wandered a little, as we tend to do. 

At a minimum, you should try to transfer these measurements:

- saddle height from pedals
- saddle setback
- bar drop
- reach 

As already mentioned, saddle setback from the cranks is hard to measure so it is commonly measured tron the bars. With the change in cranks you could assume the 5 mm offset, but I recommend reassessing your knee over pedal position.

These bikes and sizes are varied enough a new fitting session is really warranted. Transferring the measurements might get you close but probably not ideal or optimal.


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## dekindy (Jul 7, 2006)

Use a t-square to measure the vertical distance from the center of the bottom bracket to the top of the saddle.

Using the same vertical line above, measure the distance from the vertical line to the tip of the saddle.

Measure the vertical drop from the top of the saddle to the center of the handlebars.

Measure the horizontal distance from the tip of the saddle to the center of the handlebars.

These are also the measurements that a framebuilder would need to design a frame.


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