# Bobbing Titanium Seat post for Brompton



## sdawila (11 Sep 2019)

Hello everyone,

I am in the midst of confusion over the use of upgrade material for my Brompton bike. I am confused about the use of titanium seatpost which also results in bobbing when pedaling. and on the other hand the use of aluminium is also very rarely used by Brompton bicycle users.

Bobbing is commonly known amongst cyclist to be a very ineffective because energy is wasted due to titanium flexibility that cause bobbing (movement to left-right shake). 

Perhaps anyone can help by giving input or experience on this matter ? Thanks in advanced.


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## Milkfloat (11 Sep 2019)

The material choice on its own has no bearing on the flexibility of the post..


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## steveindenmark (11 Sep 2019)

Where did the bobbing and titanium seat post come from? I am sure it does not flex that much.


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## fossyant (11 Sep 2019)

Carbon will flex more if designed to. Doesn't brompton use chrome plated posts. Mainly for longevity and scratch resistance.


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## Kell (11 Sep 2019)

I've never experienced it on the standard post.

Plenty of pedal bob with the standard (and even the firm) suspension blocks.

Lots and lots of vibration in the stem, but can't say I've noticed anything untoward in the seat post.

Any vibrations in the wheels get amplified by the length of the seat post and stem, and they're so long on a Brompton, that's what causes a lot of the problems.


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## mitchibob (11 Sep 2019)

I bought a cheap titanium seatpost via ebay from Taiwan I think, primarily to help smooth the ride a bit after fitting Super Firm suspension block. I don't get any bobbing, even at pretty high cadence and I've weighed between 75kg and 63kg since I've had it. However, before getting Super Firm suspension, I would get bobbing at high cadence.

It weighs over 300g less than the standard Brompton seatpost and pentaclip. Not flanged, so can pull straight out, so more nickable, although it's rare that I've left my Brommie where that'd be a problem. I'm not a big fan of the seat attachment, but it does do the job. For 60 quid, I'm not going to complain.


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## alicat (11 Sep 2019)

My 2009 P6R-X has a titanium seat post, I believe. I can't say I've noticed any 'bobbing'.


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## fossyant (11 Sep 2019)

Its the basic suspension that causes bob. Full Suspension MTBs have sophisticated shocks and pivot set ups to eliminate this, a brompton is very basic in comparison. At worse you may get a mm or so of lateral flex in a seat post, but no vertical compliance, which is where the bob comes from. That vertical compliance is in the bikes suspension.


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## Kell (11 Sep 2019)

Get a Joseph Kuosac suspension block.

Completely eradicates pedal bob.

In the video below, you can see the bob of me pedalling my bike on a firm block (sat down) versus me stood up bouncing on the pedals on the JK block - no bobbing at all. (apologies for the sound quality - put the vid together on my phone.)

(PS - I'm 15 1/2 stone/95kg)


View: https://www.youtube.com/watch?v=BxeEln3X2qs


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## ianrauk (11 Sep 2019)

Ti certainly doesn't bob.


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## sdawila (11 Sep 2019)

steveindenmark said:


> Where did the bobbing and titanium seat post come from? I am sure it does not flex that much.


it's Bromfication, a mate got it from New York and he dislike how it performed from the day one it was installed. according to him yes it did flex that much.


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## sdawila (11 Sep 2019)

fossyant said:


> Carbon will flex more if designed to. Doesn't brompton use chrome plated posts. Mainly for longevity and scratch resistance.


right, they do use the chrome plated post and they're fine but i'm on about upgrades, either titanium alloy or aluminium alloy.


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## sdawila (11 Sep 2019)

mitchibob said:


> I bought a cheap titanium seatpost via ebay from Taiwan I think, primarily to help smooth the ride a bit after fitting Super Firm suspension block. I don't get any bobbing, even at pretty high cadence and I've weighed between 75kg and 63kg since I've had it. However, before getting Super Firm suspension, I would get bobbing at high cadence.
> 
> It weighs over 300g less than the standard Brompton seatpost and pentaclip. Not flanged, so can pull straight out, so more nickable, although it's rare that I've left my Brommie where that'd be a problem. I'm not a big fan of the seat attachment, but it does do the job. For 60 quid, I'm not going to complain.



excellent, do you mind sharing what is the brand ? I might want to get one too but since a friend of mine complained and not happy to one of the best brand for Ti upgrades in brompton.


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## sdawila (11 Sep 2019)

ianrauk said:


> Ti certainly doesn't bob.


wobble from left to right perhaps ?


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## sdawila (11 Sep 2019)

ianrauk said:


> Ti certainly doesn't bob.



check this one out


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## ianrauk (11 Sep 2019)

sdawila said:


> check this one out


Then I would say that post is not fit for purpose.


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## fossyant (11 Sep 2019)

sdawila said:


> check this one out



That's the suspension - it's basic elastomer.


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## sdawila (11 Sep 2019)

fossyant said:


> That's the suspension - it's basic elastomer.



it did say it adds suspension to your ride but it wobbles too


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## mitchibob (12 Sep 2019)

sdawila said:


> excellent, do you mind sharing what is the brand ? I might want to get one too but since a friend of mine complained and not happy to one of the best brand for Ti upgrades in brompton.



Rockbros was the brand. https://www.ebay.co.uk/itm/ROCKBROS...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649


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## fossyant (12 Sep 2019)

Rockbros do knock off everything. I've got one of their fancy 'bells' for about £3, which is an exact copy of the original that retails for north of £50.


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## mitchibob (13 Sep 2019)

fossyant said:


> Rockbros do knock off everything. I've got one of their fancy 'bells' for about £3, which is an exact copy of the original that retails for north of £50.



I must admit, I was dubious for the price, but after about 15,000km of riding on it, I'm happy with my purchase. Just don't really like the seat-clip, or at least the noise it can make after an adjustment, but quite honestly, for the price, weight, and performance in the last year and a half, very happy. Got delivered in about a week too, although, when the postman arrived with this bubble wrapped tubular shaped package and he handed it to me, I really wondered initially if I'd just been sent some bubble wrap it was so light.

However, combination of this seatpost and Joseph Kousac super-firm suspension block has been great. Better power delivery uphill, comfortable for 100mile+ rides, and no bobbing at high cadence. Thanks to others on this forum for the firm suspension tip!


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## sdawila (13 Sep 2019)

mitchibob said:


> Rockbros was the brand. https://www.ebay.co.uk/itm/ROCKBROS-Titanium-31-8mm-CNC-Seatpost-for-Brompton-Folding-Bike-New/371416219721?ssPageName=STRK:MEBIDXT&_trksid=p2057872.m2749.l2649



Thanks


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