Huge MTB faster than racy gravel?

[richardfm]

Might just be in your head, but I'd get the tape measure out and check saddle height on both bikes and make sure they are the same as a starter.

What if the cranks are different lengths or the bottom brackets different heights?
You wouldn't want the saddles the same height.

 

[sevenfourate]

What if the cranks are different lengths or the bottom brackets different heights?
You wouldn't want the saddles the same height.

Probably not hugely scientific - but i've set of my 3 'Road-bike riders' [2 x Hybrids and a Gravel bike] - by getting the seat post up to a height where i'm clearly pretty much unable to reach the bottom of the cranks stroke. And am rocking my hips to achieve that. And then lower the seatpost slightly from there.

So hence: although those 3 bikes are extremely similiar / the same in terms of the measurement from the centre of BB (Pretty sure they are all on 175mm crank length) to top of seat height; they are all different to each other / in reference to the ground if i cast a horizontal eye across them all in the garage - due to the BB to ground measurements being different.

 

[rogerzilla]

Probably not hugely scientific - but i've set of my 3 'Road-bike riders' [2 x Hybrids and a Gravel bike] - by getting the seat post up to a height where i'm clearly pretty much unable to reach the bottom of the cranks stroke. And am rocking my hips to achieve that. And then lower the seatpost slightly from there.

So hence: although those 3 bikes are extremely similiar / the same in terms of the measurement from the centre of BB (Pretty sure they are all on 175mm crank length) to top of seat height; they are all different to each other / in reference to the ground if i cast a horizontal eye across them all in the garage - due to the BB to ground measurements being different.

As a rule, power increases with saddle height until you reach the point where you're overextending your knees (which is very bad and needs to be avoided). A few mm difference is quite noticeable.

 

[sevenfourate]

As a rule, power increases with saddle height until you reach the point where you're overextending your knees (which is very bad and needs to be avoided). A few mm difference is quite noticeable.

Briliant - thankyou.

I believe from memory when i set them up - i read you should retain a 15-30 degree angle in the knee at the bottom of the stroke ?

 

[fossyant]

What if the cranks are different lengths or the bottom brackets different heights?
You wouldn't want the saddles the same height.

You measure from the centre of the crank (axel) to the rails, or top of saddle. Have to allow for different saddle heights. As for crank lengths, I run 170 on road and CX, and 175 on the MTB's - I don't notice any difference. I'm thinking here, the OP could be a few CM's out rather than a few MM.

 

[rogerzilla]

If your knee is just locked out with your HEEL on the pedal and the crank at bottom dead centre (i e. on aline projected from the seat tube) , the height is usually correct for pedalling in the normal cleat position. The complications are that shoes and cleats vary a bit, and riders who like their cleats further forward may want to go higher. At no point should your knee be near locking out during normal pedalling, nor should you be rocking your hips to reach the pedals.

 

[Bio_Carbon]

In my eyes the only way possible for the MTB to come out on top is if your MTB route was an easy fast route and your gravel bike route was a pig of a route. The advantage would sway in favour of your MTB, irrespective of extra bike weight and thicker tyres.

These anomalies you are getting? Are the routes very much the same? Have you picked out a given mixed terrain route and done it on both bikes as a gauge? And are your efforts the same? You are extremely used to your MTB, not so much with your newer gravel bike. Power differences??

Same route. I live in a village outside a very dense city of 500,000 people. I don't have a lot of options in terms of route. Mainly two, one is utter shoot and very dangerous, so that leaves one. It's about a kilometer max on gravel, another two kilometers on poorly maintained, paved paths, but then 10km on the sweetest asphalt you've ever seen and some roads. I've been commuting on that route daily and if I wanted to meet friends or have a good time out I needed to go that exact same route basically.

I have been thinking about maybe not having the thing with all those gears down that well. This may be a reason, but I'm not sure. Subjective excretion always is 100%. I don't know how to go at a comfortable pace. Those 12km always were 30 minutes full-throttle. But yeah, gears. I still need to check the breaks if those may be poorly adjusted / dragging, but due to my incident I'm still functionally disabled and have not managed to get to the bike out of its cubby last couple of days.

 

[Sharky]

One test you could do is ...

Find the longest, safest descent on your route.
From a standing start, push yourself off gently and freewheel down to the bottom of a hill and time yourself. No peddling, just freewheeling.

Do on both bikes and see if there is a difference.

Will need to repeat several times, on both bikes to consistency of data.