Frame Job

This looks OK
This fit looks OK

Last year we read that Philippe Gilbert is riding a 50cm (top tube of 535mm) BMC frame and he is 1.79m (5’10”) tall. Now it’s reported in Cyclingnews that Ritchie Porte’s Pinarello is a 46.5cm frame (top tube of 515mm) and Porte is 1.72m (5’8″) tall. He is no Nairo Quintana but somehow he is on Quintana’s old bike. Porte is just one inch shorter than the average Australian male, he is not short. And I used to think Sean Kelly’s bike was a tiny bit small for him.

Taylor Phinney was moved down from a 60cm to a 58cm frame when he joined BMC. He is 1.96m (6’5″) so it’s not a radical move, I can understand a very tall person wanting a less whippy frame, not that a BMC 60cm carbon frame is in any way loose. And they are getting the advice of people who know what they are doing, so there are some solid ideas here just ones I haven’t thought of.

What are the advantages of riding such small frames? Really, I don’t know and would like to understand. Ritchie Porte is 1.72m, rides a kid’s bike and has a 120mm stem on it, how is that a good bike fit? Has everything we learned about bike fitting been with a huge caveat: after many measurements and calculations, here is what frame you should ride but if you want to throw all that out the window and go down six centimeters, that works too. And yet, Mr Porte looks pretty good on it so tell me, oh wise ones, what am I missing?

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186 Replies to “Frame Job”

  1. Crazy to see those numbers. I am 5’8″ and on a 54cm Madone with a 130mm stem. At that I still feel a bit too forward on the bike, not all the time, but at moments. I can’t imagine going any smaller. My biggest question is how much power is lost via seat post flex when the frames are so under sized? Common sense would say when the seat post is moved farther from the top tube it becomes less supported. And are the cons of seat post flex outweighed by aerodynamics and weight reduction of smaller frames, or simply a stigma/ stubbornness of the pro’s going with what seems more beneficial vs what actually is more beneficial?

  2. stiffer, less power deflected, lower centre gravity, shorter wheel base, more responsive

  3. With a small frame you can get the seat post out more and if you whack a long stem on it you still have the reach you need but more saddle to handle bar drop than if you got the same reach/saddle height but on a larger frame… If you see most pro bikes they have a large saddle-handle bar drop that most people would find uncomfortable/crippling..  It seems a pros fit is not the same as a non-pro fit..

  4. … and much more aero (if you’re flexible enough!) due to larger saddle to bar drop

  5. Can’t really see what the issue is. Most pros ride the smallest frame they can. I’m 172cm too and ride a Ritte Bosberg with a 51.5cm top tube and a 120mm stem. It’s a perfect fit. How much power is lost by seat post flex? At a guess the square root of FA.

  6. Simple: Short tubes are stiffer and lighter. A long stem is stiffer than a longer top tube. A long seat post is light and comfortable without loosing efficiency. Finally, a small frame handles better.

    Ride the smallest frame you can get into the right position on.

  7. Because of the sloping top tubes the seat tube lengths are meaningless but these are still often short in the top tube.  With stock frame sizes, an undersized frame and long stem is a way for these guys to get lots and lots of saddle to bar drop as is the fashion nowadays.  But the bikes probably don’t handle like they are designed to.

  8. lower position. smaller frame comes with a shorter head tube. cav just went to a smaller frame too.

  9. actually I don’t find RP’s setup extreme at all – it is almost identical to mine. We have same height and I’m on a 48 cm c-c, but with 69cm saddel c-t and 172,5 arms (he has short legs). What matters the most these days is to get the saddle-to-bar drop right, without fooling around with spacers – “slam it down” I think you call it around here.

  10. For the rider it would lower and bring forward the centre of gravity (increasing bike handling – same technique for descending); and decrease the front cross-section of bike and rider that passes through the air (lowering drag to a degree).

    Maybe toe-lap stopped being a thing to worry about as well.

  11. A smaller frame with longer stem instead of top tube may provide some additional control — at race speed — when doing a monster descent.  In essence, these guys are turning themselves into pinballs and whipping themselves through the corners and the fewer centimeters extended into the void, the better.

  12. Small(er) frameset — shorter wheel base being easier to maneuver openings — and then nicer in a crash!?

  13. @Nate

    But the bikes probably don’t handle like they are designed to.

    Why would you say that? Low center of mass is always better; big frames with all the weight at the top with people cruising around in the sit up and beg position – now that’s not going to handle like the bike was designed.

  14. @frank

    @Nate

    But the bikes probably don’t handle like they are designed to.

    Why would you say that? Low center of mass is always better; big frames with all the weight at the top with people cruising around in the Sit Up and Beg position – now that’s not going to handle like the bike was designed.

    Having a low CoG is certainly important, but it’s also important to have the wheels in the right place relative to the CoG, which is pretty hard on a bike that’s too small.

  15. I really don’t understand todays bike fitting myself, but I guess I go along. I am 5’10” and I ride a 52 sloping C59, and a 56cm master X-light. The C59 looks like a kiddy frame next to my master, but it may be the 1984 filter I see it through. I do have to say the c59 doesn’t feel small riding it, it is just how they look side by side.

  16. @Nate

    @frank

    @Nate

    But the bikes probably don’t handle like they are designed to.

    Why would you say that? Low center of mass is always better; big frames with all the weight at the top with people cruising around in the Sit Up and Beg position – now that’s not going to handle like the bike was designed.

    Having a low CoG is certainly important, but it’s also important to have the wheels in the right place relative to the CoG, which is pretty hard on a bike that’s too small.

    That’s Zinn’s theory too, and in extreme it’s true,  but I’d be shocked if there was a significant difference in wheel base on a 58 vs 61 cm frame, but the 2-3 cm drop in bar height does pose a significant change.

    My VMH’s 51 vs my 61 only has about two cm difference in wheel base, and I don’t think anyone is talking about going from a 61 to a 51. Within the realm of reason, you’re deciding between one or at most two frame sizes.

    [dmalbum: path=”/velominati.com/wp-content/uploads/readers/frank/2014.01.24.13.13.51/1//”/]

  17. @EBruner

    I really don’t understand todays bike fitting myself, but I guess I go along. I am 5’10″³ and I ride a 52 sloping C59, and a 56cm master X-light. The C59 looks like a kiddy frame next to my master, but it may be the 1984 filter I see it through. I do have to say the c59 doesn’t feel small riding it, it is just how they look side by side.

    This post is useless without photos.

  18. Whenever I start looking for a 60 ctc, I have decided on a 59 ctc. And now that I intend to build up a graveur it will decidedly be a 58 Columbus SL.

  19. @norm

    @gianni it’s Richie Porte not Ritchie Port.

    And that photo points out as well that once you’re at the low end of the sizing spectrum, it all goes out the door, so a guy like him isn’t going to have the option to go smaller even if he wanted to, hence the 12cm stem and stubby post.

  20. P.G. is an interesting example Gianni however getting your position dialled just by looking at Pros bikes and reading about their measurements form bike radar etc. can get you confused.

    I believe strongly that at some point he was on a custom made BMC frame simply because there is no 50 cm BMC Team Machine – there is 48 and 51. You can look it up on a BMC geo chart. See the differences on the photos in the articles I linked below. The amount of spacers under the stem is also different. One frame 50 and one 51.

    http://roadcyclinguk.com/gear/pro-bike-philippe-gilberts-bmc-team-machine-slr01.html

    http://www.bikeradar.com/road/gear/article/pro-bike-philippe-gilberts-bmc-teammachine-slr01-36238/

    As far as his stem goes 3T stem measured c-c 140 mm in reality is a 130 mm stem by 3T. 3T stem measures 130 mm on + 6 deg. If you flip it to -6 deg it measures longer hence 140 mm measured c-c. Since his stem is 6 deg the longer the stem the higher the handlebars so he gets his height even though the HT is short.

    Personally I’m 180 cm and if I was going to buy BMC frame I’d also take 51. Their 54 which is next measures 55 TT and 148 in HT so for me they are both too long.

    Go for the smallest frame that fits you because it is lighter, stiffer and handles better. To be honest there was a few interesting articles I wanted to send you recently as far as fitting is concerned but you’d have to forward me your mail if you want of course. Your recent photos with a cigarette on a bike – I thought your bike was too big and too long and ready to escape from under you. You need to keep the frame more under you e.g. under control. Try to test ride smaller bike and see how you feel. It’s all about the feeling.

    R.P. position looks ok although from the picture it looks like his saddle is very low. He didn’t reach the bottom of the pedal stroke yet but knee angle looks fine already.

    American with black socks – rings a bell. I don’t know really.

  21. @Gianni

    Has everything we learned about bike fitting been with a huge caveat

    Yes. Basically, physiology is so complicated and we are all so uniquely built, and the the muscle dynamics of moving a pedal around a circle with force is so complex that we knew fuck all about standardizing frame fit in the 50’s and 60’s and we know fuck all about standardizing frame fit in the 2010’s.

    It all comes down to experimentation and figuring out what works for you. If you’re comfortable, that’s a good start. If you can also go batshit fast, then even better. There is science to the madness, we just haven’t gotten past the madness.

  22. @frank Thanx for pointing out that reality. I quickly assumed some sort of wheelbase difference, but drive train specs shouldn’t be dealing with extra centimeters. The down tube and fork might be the only factor in determining a wheelbase.

  23. @Gianni

    Skip the last paragraph mate. Entered too quick without deleting.

  24. @frank All my bikes are 57-57.5mm TTs.  The bikes with the longer wheelbase give a fantastic, intuitive ride.  In contrast I feel like I am perched on top of the one with the shorter wheelbase, and the bike flops over from side to side in an unpredictable way.  The difference is probably less than a cm.

    At some point I found and read a copy of the CONI manual section on frame design and it was quite interesting.

  25. @klassman

    A smaller frame with longer stem instead of top tube may provide some additional control “” at race speed “” when doing a monster descent. In essence, these guys are turning themselves into pinballs and whipping themselves through the corners and the fewer centimeters extended into the void, the better.

    I noticed this going from my 58cm TT Colnago to a 56cm TT 3Rensho.  Combined with the steep ST and a little less trail, I find myself barely needing to brake on hairpins that the Colnago would push wide on.

  26. An interesting piece. Sees s Cav’s gone down a frame size too.  He now rides a smaller frame size than Mrs @936ADL.

    To me it just underlines the fact that the needs of the pros are very different to your average  Velominatus.

  27. @Nate

    @frank All my bikes are 57-57.5mm TTs. The bikes with the longer wheelbase give a fantastic, intuitive ride. In contrast I feel like I am perched on top of the one with the shorter wheelbase, and the bike flops over from side to side in an unpredictable way. The difference is probably less than a cm.

    At some point I found and read a copy of the CONI manual section on frame design and it was quite interesting.

    I have some crit racing friends who ride teeny tiny bikes for the exact reason you’re talking about.

    I wonder if the bike size choice doesn’t also have something to do with riding style.  Some people like to turn “from the hips” while others tend to lead with the bars.  In my experience, smaller bikes lend themselves more naturally to the former style of riding.

  28. @frank

    From Greg LeMond’s Complete Book of Cycling

    Bugger off! What, you are going to end all discussions by quoting from LeMan’s book? I say foul! Since when is being informed part of the spirit of things around here?

  29. @TommyTubolare

    Go for the smallest frame that fits you because it is lighter, stiffer and handles better. To be honest there was a few interesting articles I wanted to send you recently as far as fitting is concerned but you’d have to forward me your mail if you want of course. Your recent photos with a cigarette on a bike – I thought your bike was too big and too long and ready to escape from under you. You need to keep the frame more under you e.g. under control. Try to test ride smaller bike and see how you feel. It’s all about the feeling.

    Cool, thanks for your informed input on the Gilbert BMC and my own position. N+1 my friend. I’ll send you my velominati email address so you can forward me any useful frame information. My previous bike, my Merlin was a 63cm frame, obviously too big so the Serotta seemed an improvement, which it is. But if mini-phinney is on a 58cm frame and he is larger than I am, I should go smaller. 

  30. @EBruner

    I really don’t understand todays bike fitting myself, but I guess I go along. I am 5’10″³ and I ride a 52 sloping C59, and a 56cm master X-light. The C59 looks like a kiddy frame next to my master, but it may be the 1984 filter I see it through. I do have to say the c59 doesn’t feel small riding it, it is just how they look side by side.

    Colnago has a tricky (confusing Italian) size chart for their sloping frames too. They have confused a few people with it. I bet your C59 effective top tube length is closer to your Master’s. Yes, do put up a side by side comparison photo, so we can admire some Colnagos. I loves me a C59 and a Master.

  31. When I had a bike fitting, it was suggested that as long as the contact points were correct, you should go for as small a frame as possible. Technically according to the Cervelo measurement charts I should be on a 56 cm frame (and had one), but after the fitting I now ride a 54 cm frame with a slightly longer stem and larger saddle to bar drop – the difference in performance/efficiency is genuinely noticeable – I’m a convert to smaller frames, even though club mates reckon I should be on a larger frame! (I smile as I kick their arses).

  32. this topic popped up on velocipede a while ago.  tom kellogg ended it pretty effectively by posting a pic of his own frame (52 seat tube and a 58 top tube, or something ridiculous like that)–which works for him because of his own combination of anatomy and flexibility.

    his point was: don’t look at other people’s fits.  figure out what works for you: use the measuring and fitting as guides, not absolute rules.  realize your position will change slightly over time for a variety of reasons and don’t be afraid to learn to listen to what your body’s telling you.  you might not be able to tell if you’ve been compensating for a leg-length discrepancy without expert help, but once you get a good functional fit that works for you trust it, and don’t go looking around at what might or might not work for other people.

    or,  take a good long look at sean kelly.

  33. @richard mclamore

    Good points. I remember Christian VDV talking about getting back on his race bike after some time off. Man this saddle is high, these bars are low and this stem is long. Those guys are all on one end of the spectrum of bike fit. Most of us can’t and wouldn’t want that fit. And as we get older we can’t get as long and low either, I can’t.

  34. I’ve posted this before but its worth another airing. ’55X11 for ye anoraks’

    Obree, isn’t scared of a long top tube….

  35. I recently got a retul fit done (a gift). It went as expected; “the computer says your back angle is to low”. Even if I was comfortable with my 12cm of bar drop, he wanted to give me 8.5cm. I didn’t buy a 54 with a 120mm head tube so I could ride it with 4cm of spacers.

  36. @Nate

    @frank All my bikes are 57-57.5mm TTs. The bikes with the longer wheelbase give a fantastic, intuitive ride. In contrast I feel like I am perched on top of the one with the shorter wheelbase, and the bike flops over from side to side in an unpredictable way. The difference is probably less than a cm.

    At some point I found and read a copy of the CONI manual section on frame design and it was quite interesting.

    That’s not because of the wheelbase so much as it is the geometry; your bike with the shorter wheel base probably has a higher bottom bracket which is what gives you that feeling of being perched up and out of control.

    Longer wheelbases are more stable, shorter more responsive; then HT angles and how tight the rear wheel is under the frame start to matter a lot as well. CX bikes have very steep head tubes because it is more stable…it all gets really fucking cool when you mix them together, but the point to remember is that none of these factors independently answer the question.

    The physics at the core is lower the center of mass for stability, shorten the wheelbase for responsiveness and extend it for comfort. Merckx’s geometry was designed around a combination of stability (low bb) and comfort (long wheel base) so he could catch up to the climbers on the descents.

  37. 1.72m is not short!!!

    My fucking word. I have been waiting my entire life for some tall bastard to confirm what I already knew!

    Thank you, Gianni. This means a lot to me. All these years fighting the good fight, now it’s been confirmed that I’m a Medium-Sized Man. Fuckin’ rockin’. I’m gonna have me a good Friday night.

  38. This trend has been taken to such extremes in track that many riders need riser stems to get their bars up high enough. The tiny frames seem especially comical paired with legs bigger than most road pros’ waists.

  39. @Ron

    1.72m is not short!!!

    My fucking word. I have been waiting my entire life for some tall bastard to confirm what I already knew!

    Thank you, Gianni. This means a lot to me. All these years fighting the good fight, now it’s been confirmed that I’m a Medium-Sized Man. Fuckin’ rockin’. I’m gonna have me a good Friday night.

    Let it be noted that I do try to help the humans now and again.

  40. Hmm, interesting.  I’m 6’0 and I ride a Giant TCR with a 57 top tube.  I used to have the size down – a 55, from memory, and I hated it.  I tried all sorts of dangly stem lengths, constantly felt cramped up, had back pain, and felt like I was always three steps away from chucking it into the bushes on any descent even moderately twisty – the front wheel always felt overloaded.  Feel much more “in” the bike than “on” it now, if that makes sense – much more confidence inspiring.

    Got to say that when I’m racing having something that handles sharper isn’t really something that’s too far up the list – there’s already so much going on the last thing I want to worry about is handling that’s too quick for me, or a front wheel inclined to wonder when I’m wrestling myself out of a cape…difference between me and the pros, I guess.

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