Hi all, I am newcomer here, since I am still riding SC Blur LT. I love the bike, but there are several reasons for change. The most important is that my LBS stops the SC business nad is going to start with IBIS. So as always when planning new bike there is big question aboout size. I am 5' 11" (181 cm) and I have BLT in L size with straight Thomson seatpost and Ritchey 10 cm stem (6 degree rise) which is installed with negative rise (is it understandable ?). The effective top tube length is 23.5" and cockpit fits very well. The set up is excellent especially for climbing. But I feel I could have Mojo in M size, the effective top tube of which is 22.8 " but with layback Thomson, which together gives exactly the same cockpit as my BLT. I will level the head tube size difference by installing stem with positive rise. I would appriciate your oppinions because I am affraid I will not have possibility to do test rides with two different setups. I must hit the target with the first shot. Thanks guys.
monolink
IMHO, Yikes I don't know if I would not go and check out the medium and the large Moj first. Don't you want your seat position and saddle pedal spindle spin measurement to be similar on both bikes and having to setback the seat on med. for the sake of tt length would change that. (but since blt is 72.5 seatangle and moj is 73 you could set back to compensate for that reason (pedaling position.) Then the .5 degree difference in head angle (this time the other way 69.5 to 69) would get you close (going from large to large size mind you) Then finish off with corrections between the 2 with correct stem height/lenght/rise.
For what it's worth, I ride a medium blur classic, with a slightly longer top tube than the LTs if I remember right and at 5'9" I'm having a real problem with the Moj Medium top tube sizing. (Not that it's wrong for most people it's spot on but I like being stretched out more racer like, less freeride like. Here are some measurements I got. Probably not exact but just an opinion....Moj med top tube real 21.50 "effective" for me, (measured 29.5" above crank center on seat post and parrallel to headtube and compensating for the 73/69 seat/head angle) Also non "effective" I got 22.25. (btw, it is different on blur classic vs blt because of head angle, which makes my problem more difficult going to slacker head angle I mean.)
On the large I got 22.5 effective and 23.10 or noneffective.
Note: Effective for me would be measured at parrallel at my seat height and calculating offset for seat and head angles. When you see charts for most un-effective tt measurements, they seem to cancel out head and seat angle which are very important for ergonomic biomechanical fitting (They actually have more affect than you might imagine.) For instance attempting to measure claimed effective 23 tt measured ct73/ht72 vs ct72/ht69.6 yields quite a different result (at least when I do it "my effective tt" )
Bike responsiveness between the 2 ? Well, like most full suspension bikes unfortunately all sized in the line have the same size rear triangle and of note I measured the same size back section mold on the front triangle nearest seattube. So, the second section mold or hole what-ever-you-want-to-call-it on the headtube side had the extension to make it larger. (but it looks like the front mold is the same and just extended carbon from there but I haven't measure that. Given the above, the large should be as stiff as a medium laterally, well almost (wheelbase given)) Also, look at photos of the 2 and notice similar standover (.44 diff) with the large offering only longer support section raised up to seatclamp, but like I said the back triangle mold on the bikes appears identical) I don't know if the layups are beefier on the large. That would be a good one for Hans when he has time.
But given the above and with about (I'm guessing from what I remember) .07600 Pounds = 34.47302 Grams of weight difference between the 2, I wouldn't let it be a huge deciding factor. (You are getting back almost a pound and 1/2 over your current frame ! I think blt large frame is @ 6.4~ lbs)
If you were running a 90 or shorter stem on you large blt I would be maybe look at the medium if I were you. But seems like with 100 or 110 aren't you pretty spot on in fit ?
Blt (from website) large st19.5 centertotop at 72.5 and tt at 23.5 centertocenter at 69.5. (although sc fudges there top tube lengths)
Moj would be tt 19/73 and 23.6/69 (slacker head angle by .5 may short up your reach slightly. Btw, I measure their effective at 23.25 or less certainly not 23.6 if measured ctocenter)
Just one guy's take who obviously has way too much time on his hands this AM :yawn: . (I'm about to dirt demo both sizes next week, though.)
Here is another thread on this stuff. It's a question ask many times on the Ibis forum and the company owners actually respond ! Few bike companies do that. Also, Derby helps out allot with this stuff. (In a much more concise and readable manner, than I can do ! :thumbsup: ) The sizing is so similar between Moj and Blurs maybe Ibis used blurs as a starting point from a geometry perspective when they started designing em.
Here's a latest hash.
http://forums.mtbr.com/showthread.php?p=3527985#poststop
This is another good one. I am thinking of doing the photoshop thing but it's really difficult cause it's easy to get false visuals with just a slight difference in pic distance and angle.
http://forums.mtbr.com/showthread.php?t=239835&highlight=mojo+sizing+medium+large
Also, note wheelbase moj large is 43.5 or blt large 43.8 but going down to med moj shrinks you down to 42.7 cramped for your height I would imagine. (Moj is slightly shorter with the chainstay length of 16.89 " vs the blt's 17.2 ) Take all with a grain of salt, everthing depends on feel on the bike, so I'll know more next week.
My rationalization for moving to new bike from Blur is Sc hasnt' spent any of their money on real R&D or I would love a full carbon VPP Blur. (I'm a big ring out-off-the-saddle climber) Sorry for long post it helps me to talk thru this sizing stuff and I'm right in between sizes.
For what it's worth, I ride a medium blur classic, with a slightly longer top tube than the LTs if I remember right and at 5'9" I'm having a real problem with the Moj Medium top tube sizing. (Not that it's wrong for most people it's spot on but I like being stretched out more racer like, less freeride like. Here are some measurements I got. Probably not exact but just an opinion....Moj med top tube real 21.50 "effective" for me, (measured 29.5" above crank center on seat post and parrallel to headtube and compensating for the 73/69 seat/head angle) Also non "effective" I got 22.25. (btw, it is different on blur classic vs blt because of head angle, which makes my problem more difficult going to slacker head angle I mean.)
On the large I got 22.5 effective and 23.10 or noneffective.
Note: Effective for me would be measured at parrallel at my seat height and calculating offset for seat and head angles. When you see charts for most un-effective tt measurements, they seem to cancel out head and seat angle which are very important for ergonomic biomechanical fitting (They actually have more affect than you might imagine.) For instance attempting to measure claimed effective 23 tt measured ct73/ht72 vs ct72/ht69.6 yields quite a different result (at least when I do it "my effective tt" )
Bike responsiveness between the 2 ? Well, like most full suspension bikes unfortunately all sized in the line have the same size rear triangle and of note I measured the same size back section mold on the front triangle nearest seattube. So, the second section mold or hole what-ever-you-want-to-call-it on the headtube side had the extension to make it larger. (but it looks like the front mold is the same and just extended carbon from there but I haven't measure that. Given the above, the large should be as stiff as a medium laterally, well almost (wheelbase given)) Also, look at photos of the 2 and notice similar standover (.44 diff) with the large offering only longer support section raised up to seatclamp, but like I said the back triangle mold on the bikes appears identical) I don't know if the layups are beefier on the large. That would be a good one for Hans when he has time.
But given the above and with about (I'm guessing from what I remember) .07600 Pounds = 34.47302 Grams of weight difference between the 2, I wouldn't let it be a huge deciding factor. (You are getting back almost a pound and 1/2 over your current frame ! I think blt large frame is @ 6.4~ lbs)
If you were running a 90 or shorter stem on you large blt I would be maybe look at the medium if I were you. But seems like with 100 or 110 aren't you pretty spot on in fit ?
Blt (from website) large st19.5 centertotop at 72.5 and tt at 23.5 centertocenter at 69.5. (although sc fudges there top tube lengths)
Moj would be tt 19/73 and 23.6/69 (slacker head angle by .5 may short up your reach slightly. Btw, I measure their effective at 23.25 or less certainly not 23.6 if measured ctocenter)
Just one guy's take who obviously has way too much time on his hands this AM :yawn: . (I'm about to dirt demo both sizes next week, though.)
Here is another thread on this stuff. It's a question ask many times on the Ibis forum and the company owners actually respond ! Few bike companies do that. Also, Derby helps out allot with this stuff. (In a much more concise and readable manner, than I can do ! :thumbsup: ) The sizing is so similar between Moj and Blurs maybe Ibis used blurs as a starting point from a geometry perspective when they started designing em.
Here's a latest hash.
http://forums.mtbr.com/showthread.php?p=3527985#poststop
This is another good one. I am thinking of doing the photoshop thing but it's really difficult cause it's easy to get false visuals with just a slight difference in pic distance and angle.
http://forums.mtbr.com/showthread.php?t=239835&highlight=mojo+sizing+medium+large
Also, note wheelbase moj large is 43.5 or blt large 43.8 but going down to med moj shrinks you down to 42.7 cramped for your height I would imagine. (Moj is slightly shorter with the chainstay length of 16.89 " vs the blt's 17.2 ) Take all with a grain of salt, everthing depends on feel on the bike, so I'll know more next week.
My rationalization for moving to new bike from Blur is Sc hasnt' spent any of their money on real R&D or I would love a full carbon VPP Blur. (I'm a big ring out-off-the-saddle climber) Sorry for long post it helps me to talk thru this sizing stuff and I'm right in between sizes.
If you do much climbing, stay with the Mojo Large size like your Blur LT to keep your seat centered and body position over the pedals for better climbing power and efficiency. When climbing with a layback seat postion you will need to strain your upper body and arms pulling the bars and use more energy while climbing to keep weight forward to power the pedals.
If you have almost no climbing, the medium would be more nimble for very tight and rough terrain, but less stable and less relaxing overall to ride compared to your Blur LT.
If you have almost no climbing, the medium would be more nimble for very tight and rough terrain, but less stable and less relaxing overall to ride compared to your Blur LT.
Monolink---Check this Ibis forum for some older threads on Mojo sizing...lots of good info in many posts on this subject. Good luck---with good set up you'll be happy either way.
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