steel bike, geometry and performance

Discuss light weight issues concerning mountain bikes & parts.

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devinci
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by devinci

Need some opinions from you fellow weenies out there.

I am riding a RM vertex 29er. A pretty light carbon bike, XO equiped with some XX, RS sid RL and some light racing wheels. The frame must weight arround 950g.

I have a sponsorship opportunity for next season. Thing is the sponsorship involves some handmade columbus steel frames which are about double the weight of my vertex: 1850g approx.

The weight is a factor for me because im racing a lot and I need a good bike that wont slow me down and be hard to accelerate all the time. The other factor is the steel bike geometry: the TT is 12mm longer, the WB is 20mm longer (big concern?) and the CS length is 12mm longer. I am concerned with the WB being longer, will it make the bike feel much slower in the corners?

I'd get the new bike equiped full XTR and with a fox fork.

Thanks for insights.

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yourdaguy
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by yourdaguy

I would not take the deal unless you don't care about winning. Way stretched out steel frames are not for racing and this sponsorship seems kind of mis-directed. They should be promoting these frames for people that want an easy riding comfortable bike and those people are not racers.
For certain parts stiffer is more important than lighter.

by Weenie


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devinci
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by devinci

can you elaborate? Too long a WB?

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yourdaguy
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by yourdaguy

Longer WB will slow down how fast you can maneuver. When you are racing in places with switchbacks, etc. you will have to take them slower since you can't turn as tight an arc.
For certain parts stiffer is more important than lighter.

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Cyco
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by Cyco

I somehow doubt a wheelbase increase of 1.9% will totally prevent a rider's ability to win a race.

I would be looking closely at position. The geometry sounds like it will have a steeper head tube, and slacker seat tube to generate the stated numbers, so you will have to see how you fit on it.

The XTR/Fox combo will also be heavier then the XX/RS combo, so weight will play a bigger factor.
Success is how far you you bounce back up after being knocked down

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devinci
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by devinci

Humm not sure how much the XTR fox will be heavier but it should"nt be too bad. My current bike is full XO except grip shift XX.

The whole geometry thing has me thinking a lot.

krzysiekmz
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by krzysiekmz

Geometry is a bit different but so is the frame material and properties.

Would you be able to test ride the bike/frame at LBS for example?

Chris.
Orbea Oiz - xxxx
MSC Koncept Carbon Di2 - 6955g
Leichtkraft Team Carbon - 6868g.

TheRookie
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by TheRookie

XTR should be a few g lighter than XO but you'll add a bit back with trigger shifters (unless you get some gripshifts for the XTR, bikediscount.de do some for about €40 for Shimano 10speed) from memory the Fox is a few g heavier than the SID.

Can you not move down a frame size to keep it more compact and use the seatpost and spacers to get back to where you are now?

I just can't see the logic of adding 1Kg to the bike and expecting to be as fast and giving them the coverage they want/expect, not going to happen.
Impoverished weight weenie wanna-be!
Budget 26" HT build viewtopic.php?f=10&t=110956

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devinci
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by devinci

Good point TheRookie

here is the "new" bike geometry chart with ym current measure between ()

Small
ST: 406 (432)
TT: 575 (592)
CS: 445 (433)
STA: 73,5 (73)
HTA: 70 (70,25)
WB: 1087 (1087)
HTL: 102 (100)

Medium
ST: 457
TT: 605
CS: 445
STA: 73
HTA: 70
WB: 1111
HTL: 102

that would help a lot if you could analyse the measurements. Thanks

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michel2
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by michel2

I do not belive for a second that the steel frame is going to slow you down.
Sure a lightweight carbon frame or a lower bike weight might be good for the motivation but i honestly dont see 400 grams in a frame having huge disadvantages.

If you would be ridding heavy wheels or shitty tires i would have more concern. Geometry is something that might a litle getting used to...

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devinci
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by devinci

the frame is about 800g heavier so around 2 lbs heavier.

The geometry is actually a bigger concern for me then the weight is.

TheRookie
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by TheRookie

I'd definately be going with the small if you do it....
Impoverished weight weenie wanna-be!
Budget 26" HT build viewtopic.php?f=10&t=110956

DanW
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by DanW

If the "TT" length is an "effective top tube length" then I would personally say you will notice a difference in either the new small or medium sizes (assuming your current bike fits perfectly). For example on the small you would probably be looking at a 110 or 120mm stem compared to the 100mm stem on your RM and I'm not sure if that would handle great with the reasonably wide bars you run. Steering would be slower and probably feel a bit more cumbersome in the slow singletrack where you might also feel like you are tucking over the front wheel a bit with your weight further forward on the bike (hard to describe!). Climbing out of the saddle with your weight centered too far forwards on a smaller frame might be hard going too with the rear wheel skipping all over the place. Kind of the opposite for the large new frame where you would be on a 80 or 90mm stem to keep your reach the same. I would have thought longer wheelbase and shorter stem required for the new medium would more or less balance each other out with how slow or nippy the steering feels and ride better than the small, especially out of the saddle where it should be easier to get your weight distribution better.

I think the main point is that the geometry looks different enough to feel some difference in the ride. Whether or not it the difference in feel is something you get used to quickly or simply can't get on with I don't know!

If it handmade steel surely this is the best material and manufacturing process to get custom geometry... Is that an option?

TheRookie
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by TheRookie

HA is pretty much the same, WB the same, logic says to move the saddle back to the same effective place lengthening the cockpit and he'll be in the same place on the same WB....or is that too obvious?

So either a setback in place of inline or a greater setback post combined with sliding the saddle back if necesary to the limit on the rails.
Impoverished weight weenie wanna-be!
Budget 26" HT build viewtopic.php?f=10&t=110956

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devinci
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by devinci

I would Idealy like to keep a reasonably short stem, 100mm

I have a 25mm setback seapost waiting for a build...

by Weenie


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