54 or 56cm BMC Team Machine

tonyhogg

I'm currently riding a scott cr1 in medium 54, it's a compact. I'm 5ft 10.5, 32" inside leg, my current bike feels slightly cramped when in the drop etc but its ok I suppose, I just don't want to make any mistakes on my next bike http://www.evanscycles.com/products/bmc ... e-ec052717

Any helpful tips or advice to look out for on sizing when I'm trying both sizes this weekend?

pitchshifter

If you're dropping that amount of money on a new bike you should probably test ride it in both sizes.

stepdavi

Im sure evans will throw in a bike fit if you spend £6k in the shop

paul2718

It might be worth getting your current bike to fit properly before making big decisions on frame size for your new one. Also I would guess that the BMC will be longer and lower at the front than the CR1 for a given frame size.

IME if you can get to a competent bike fitter then £100 in that direction would be a wise investment.

Paul

tonyhogg

just had a few 'advanced' riders observe me recently on my bike and say its definitely too small for me and I need to have a more stretched out position, I just think I'm at the top end of a medium 54cm size and just at the bottom end of a large 56cm if that makes sense, really not sure until I try both bikes. I'm still comparing bike sizes in small/medium/large and thinking of mountain bikes for stand over clearance but this doesn't really apply so much on a road bike.

ozzzyosborn206

what size stem have you got on your scott? lots of people tend to be getting smaller frames and sticking 120mm stems on, thats what I am doing on my new frame but not got it yet so can't report back on how it goes.

tonyhogg

I've got the same standard stem on my cr1 it came with, 110mm I think, but your right there is always that option if I buy a medium 54cm that I could put a slightly longer stem on....decisions decisions!

bernithebiker

Hard to say without seeing you on the bike, but I would go for the 56.

If you've already got a 110 stem on your 54, then that's quite long already. Of course you can go to 130, but it might look odd, and then you need to think about seat height, etc..etc...

I'm a fair bit shorter than you at 5'8, and I ride an S Works SL4 in a 54. It's pretty much a perfect fit, but if I was forced to choose between a 52 and a 56, I'd go 56.

neeb

The BMC in size 54 should fit about the same as your current bike, whereas the 56 will have about an extra cm of reach. The headtube length of your current bike is pretty much in between the BMC 54 and 56, so assuming the same fork lengths (which might not be the same) you'll be running a few mm more spacers on the 54 BMC than on your current bike and a few less on the 56 BMC for the same bar height.

Nothing wrong with a 120mm or 130mm stem, but if you are sure you need more reach than on your current bike you'd be better going with the 56 and sticking with a 110mm stem.

Do you think your saddle position is "dialed in"? If your saddle is too far forward than is ideal and you correct it by moving it back that would increase reach. But you shouldn't do that in order to increase reach, just saying that if you are not sure about your ideal saddle position it's another factor you need to take into account.

How much spacers + headset cap are you running underneath the stem on your CR1?

mfin

Don't forget BB drop when thinking about Head Tube lengths, if the two bikes don't have the same BB drop then this will have to be taken into account.

neeb

mfin wrote:

Don't forget BB drop when thinking about Head Tube lengths, if the two bikes don't have the same BB drop then this will have to be taken into account.

Yup, the BMC has 2mm more drop, which makes the headtubes effectively 2mm higher. In theory based on that alone the BMC 54 would need 4mm more spacers, BMC 56 would need 9mm less spacers to get the same bar drop relative to the saddle assuming that the forks are the same length..

**BUT** it seems that the CR1 has a fork that is about 1cm longer than standard (as I happen to know that the Foil also does). Just noticed that the geo charts for both the BMC and the CR1 give stack, and the CR1 54 is 565mm, exactly same as the 56 BMC (which must be due to a longer fork). The 54 BMC has a stack 15mm lower, so you'd need an extra 15mm of spacers.

So for head tube length at least, the BMC 56 would be a better fit, assuming that you don't have the stem slammed on the CR1 and need to go lower...

tonyhogg

Wow, thanks a lot, my cr1 in 54cm medium is standard stock setup I've done nothing to it, I'm really feeling pushed towards to 56cm in the bmc now, my seat could go further back on my current cr1 and the spacers could be removed and I think it would still be comfortable and a slightly better fit perhaps. Only concerns I have with the 56cm bmc is my reach might be fully stretched out and it'll cause me pain long term and end up regret buying it and not be able to correct the fit as I would with a 54cm. Bit of a strange one I'm a size 7 foot and my hands are tiny, arm reach is pretty normal and leg length torso etc, lol

I fit within the parameters of both 54 and 56 for my height which has got me confused according to Evans website???

Thanks for the input, it's a big purchase, I may pay for the bg fit with another local bike shop...£120 2 hours

neeb

tonyhogg wrote:

Only concerns I have with the 56cm bmc is my reach might be fully stretched out and it'll cause me pain long term and end up regret buying it and not be able to correct the fit as I would with a 54cm.

Worst comes to the worst you could run a 100mm stem on the 56. Definitely worth getting a bike fit from a good fitter before spending that sort of money though...

Grill

54, clearly. Shouldn't even be a question.

neeb

Grill wrote:

54, clearly. Shouldn't even be a question.

That was my first thought based on height, but the OP says he feels and looks cramped on his current (similarly proportioned) size 54, and thinking about it, he's nearly 5'11" - I'm 5'9" and the 54 would be my size, so he could easily be a 56.

I think a good bike fit would be the best approach, mainly to get the saddle position sorted out. If he's just been riding his current bike "as is" without experimenting with setup he could be way out, and that could impact on reach indirectly.

bernithebiker

Grill wrote:

54, clearly. Shouldn't even be a question.

Why? Everything's screaming 56 for me..?!

MrSweary

pitchshifter wrote:

If you're dropping that amount of money on a new bike you should probably test ride it in both sizes.

And spend the extra £200-300 and get a proper fitting done. In actual fact a lot of places do consultations to see if a given geometry will work for you. If you are anywhere near West London / Reading go and see Bike Whisperer - he'll do a consultation before you buy and a fitting after. You won't regret it and it'll be more than worth the money in the end.

Sadly asking on a forum isn't going to get you a properly fitted bike.

on-yer-bike

mfin wrote:

Don't forget BB drop when thinking about Head Tube lengths, if the two bikes don't have the same BB drop then this will have to be taken into account.

Is this because the saddle is effectively lowered in relation to the bars?

neeb

MrSweary wrote:

Sadly asking on a forum isn't going to get you a properly fitted bike.

If you have a reference point for your correct fit it can tell you whether something else will fit (e.g. if your current bike is perfect and you are wondering what size to get in another model).

But if you don't have a quantifiable reference point, then it isn't going to help much.

MrSweary

neeb wrote:

MrSweary wrote:

Sadly asking on a forum isn't going to get you a properly fitted bike.

If you have a reference point for your correct fit it can tell you whether something else will fit (e.g. if your current bike is perfect and you are wondering what size to get in another model).

But if you don't have a quantifiable reference point, then it isn't going to help much.

If your current bike is a perfect fit then you've probably had a bike fitting already so you know what geometry suits your body shape / flexibility / physical abnomalities / riding style etc and yes, you may be able to pick another based on this. Chances are if that is the case you won't be asking on a forum and in any case my point above stands.

Above all this I don't understand the mentality of spending upwards of £3500 on a bike and not spending the extra £300 on a proper fitting. Maybe it comes down to not understanding the benefits of getting a fitting. Seems odd to me though.

neeb

MrSweary wrote:

If your current bike is a perfect fit then you've probably had a bike fitting already so you know what geometry suits your body shape / flexibility / physical abnomalities / riding style etc and yes, you may be able to pick another based on this. Chances are if that is the case you won't be asking on a forum and in any case my point above stands.

Above all this I don't understand the mentality of spending upwards of £3500 on a bike and not spending the extra £300 on a proper fitting. Maybe it comes down to not understanding the benefits of getting a fitting. Seems odd to me though.

Mostly agree, except that 1) it's perfectly possible to to know what fits you without having had a bike fit if you've had enough experience and have experimented. 2) Lots of people who know their fit (in one manner or another) don't fully understand bike geometry and don't know how to compare fit precisely between two different bikes. This is where advice on forums can be useful.

MrSweary

neeb wrote:

MrSweary wrote:

If your current bike is a perfect fit then you've probably had a bike fitting already so you know what geometry suits your body shape / flexibility / physical abnomalities / riding style etc and yes, you may be able to pick another based on this. Chances are if that is the case you won't be asking on a forum and in any case my point above stands.

Above all this I don't understand the mentality of spending upwards of £3500 on a bike and not spending the extra £300 on a proper fitting. Maybe it comes down to not understanding the benefits of getting a fitting. Seems odd to me though.

Mostly agree, except that 1) it's perfectly possible to to know what fits you without having had a bike fit if you've had enough experience and have experimented. 2) Lots of people who know their fit (in one manner or another) don't fully understand bike geometry and don't know how to compare fit precisely between two different bikes. This is where advice on forums can be useful.

I don't mean to denigrate your knowlege of geometry (it is certainly better than mine!).

Ok, two different things - I'd agree it may be possible to know what may fit you - with years of riding experience behind you. What you may not know is whether there are seemingly tiny adjustments that may prevent future injury or make you more efficient for your style of riding. Maybe, not esssential but not huge money to find out in the grand scheme of things. On the flipside there are doubtless very many riders around who think they know what fits them purely because they ride without obvious injury or discomfort without having a properly fitting bike. Cleat positioning for instance is notoriously hard to get right without outside help.

In any case if 1) is true then you won't be asking on a forum. As for 2) I don't see how someone who hasn't seen you on a bike, doesn't know what sort of riding you do and doesn't know your phisique can really help you get a properly fitting bike. They may be able to get you into the ball park - but probably no further. If you are at the stage of asking 56 or 54 then I'd suggest a bike fit or even just a consultation to help you decide.

Again though, if you're spending >£3500 on a bike and your asking on a forum which size fits you - in the nicest possible way, you're doing it wrong.

Also it is worth noting that I am insanely jealous of anyone who can afford a Team Machine - probably one of my dream bikes. Do it justice and get fitted!

Grill

bernithebiker wrote:

Grill wrote:

54, clearly. Shouldn't even be a question.

Why? Everything's screaming 56 for me..?!

The BMC in a 54 has a slightly longer reach than the CR1 in a 54, so for an identical fit he'd have to go down to a 105mm stem w/ 15mm of spacers. The BMC has a slacker seat tube angle as well which means his saddle would be farther forward on the rails (if the seatposts have the same layback) to get the same KOPS (which is BS but some people worry about) which would give lost identical reach. In the end he'll have far more adjustability with the 54 whereas if the 56 feels a bit big it will always remain uncomfortable. FWIW I'm just shy of 6' and would ride both in a 54. When in doubt go small.

bobones

I agree with Grill. 54 with a longer stem if required. I'm 5'11 with 34" inside leg and can ride either a 54 or a 56, but the 54 with a longer stem will get me lower and longer than a 56 in the same bike. I also have a 54 CR1, a 56 Felt F and and a 56 Trek H2.

tonyhogg

thanks for the great advice, yes its a dream bike for me and i certainly don't want to get the fit wrong, I will definitely be getting a professional fit done before I purchase. Just because I ride pain free currently on my 54cm CR1, you could get used to a bad riding position etc. It's a BG body geometry 2 hour session I'm booking in, only thing is I should be taking my new bike the bmc not the old cr1, but I suppose it will tell me whether to go up in size or not for sure.

Grill

Where are you getting the fit?

neeb

Grill wrote:

The BMC in a 54 has a slightly longer reach than the CR1 in a 54, so for an identical fit he'd have to go down to a 105mm stem w/ 15mm of spacers.

Well, the BMC in 54 has a reach 4mm longer than the CR1 in 54, but remember that frame reach is measured to the top of the headtube and the BMC 54 has a shorter headtube at 148mm as opposed to 156 on the CR1. So once you bring the bars on the BMC up to the same height, the reach will be less, because the steering axis is sloped. My guess is that the final reach of the two bikes in sizes 54 once you set them up with the bars at the same height will be within 2mm or so, i.e. effectively the same. There is a great little Excel tool available online that will calculate frame reach, reach including spacers, and total reach including spacers and stem (taking into account slope of the stem etc). It also lets you calculate fork length if you already know stack (or visa-versa), which is pretty useful:

http://bb2stem.blogspot.fi/

I can't be bothered right now to type in all of the data, but this is the best way to exactly compare two frames / setups. It works best if you download it instead of using the online version.

Grill wrote:

The BMC has a slacker seat tube angle as well which means his saddle would be farther forward on the rails (if the seatposts have the same layback) to get the same KOPS (which is BS but some people worry about) which would give lost identical reach.

Figures for reach in geo charts are independent of seat tube angle; frame reach is the horizontal distance between a vertical line through the BB and the top of the headtube. On two bikes with identical reach but different seat tube angles, the top tube lengths will be different, and the saddle setbacks will be different to get the same position with respect to the BB, but the reach will still be the same on both bikes. Reach allows you to work out the reach to the bars independent of both top tube length and seat tube angle, which vary inversely in relation to each other for a given reach and saddle position with respect to the BB.

tonyhogg

and I still don't know, it's driving me crazy!

http://www.bmc-racing.com/int-en/bikes/ ... /dura_ace/

put these measurements inseam: 32inches, trunk: 24.5, forearm 14, arm 26, thigh 23.5, lower leg 21, sternal notch 58, total height 70.5 in to this website http://www.competitivecyclist.com

confused about the seat tube height, its saying a size 56 suits me best but everything else is pointing towards a 54cm frame???

can someone else put there measurements in and see what it brings up for them please.

Grill

Seat tube height is a red herring as you can always run more seat post and the rest of the geometry is unaffected. I'm almost identical in size and would ride a 54.

tonyhogg

thanks, need more of this to put my mind at rest until the bike fit...

neeb

tonyhogg wrote:

and I still don't know, it's driving me crazy!

http://www.bmc-racing.com/int-en/bikes/ ... /dura_ace/

put these measurements inseam: 32inches, trunk: 24.5, forearm 14, arm 26, thigh 23.5, lower leg 21, sternal notch 58, total height 70.5 in to this website http://www.competitivecyclist.com

confused about the seat tube height, its saying a size 56 suits me best but everything else is pointing towards a 54cm frame???

can someone else put there measurements in and see what it brings up for them please.

Here's what I would do:

1) Get your fit right on your current bike - you said you thought you might be not stretched out enough but you are not too sure. This could involve a bike fit, changing the position of the saddle and/or bar height and a possibly new stem (as well as some proper rides to test out any changes), but if you don't have a solid reference point for your fit it's always going to be a gamble choosing the size of the BMC. You can't really work this out with online tools and measuring yourself.

2) Decide if you want a bike that fits the same as your current (properly fitted) bike, except with an extra 1 or 2 cm of spacers. In this case you need the 54. If you decide that your current bike is definitely too small and/or the stem is too long and/or you would have a huge stack of spacers, you need the 56.