Spa Wayfarer with 27.5" wheels

[UpWrong]

So you're thinking of fitting smaller wheels in order to lower the BB and thus the seatpost, in order to fit this sprung seatpost. What I don't follow is the reason for fitting shorter cranks. Your legs aren't going to shrink... so either you're worried about pedal strike, in which case, is the BB really going to drop 20mm? Or the bike is too big anyway, in which case...

Rim size change: 622-584=38mm / 2 = 19 mm, ergo BB height is reduced by 19mm. Yes, worried about pedal strike.

[UpWrong]

If its not a rude question, why is a suspension seatpost essential?
I have a bad case of the "princess and the pea delusion" which means I am driven to adjust my saddle height when I change between SPD shoes and SPD boots. The adjustment is less than 5mm, but I just have to do it, I can't leave it and be comfortable. I run about 4 bikes at any one time, and saddle height is adjusted to within 3 millimetres; saddle setback, reach to the bars and bar height are OK plus/minus 5mm. (just as well, as stems come in 10mm increments!).
Cleat placement probably varies a couple of millimetres between different shoes.
I think I would prefer to have a puncture every ride to having my saddle move up and down as I ride!
Off road I find I can ride in contact with the saddle but with no real weight on it (and therefore no jarring), my weight is mainly on the pedals....I am pulling back/up on the bars in order to do this.

Have you tried a parallelogram suspension seat post? I used the Suntour NCX on my Thorn Audax Mk3 - awesome! The theory is that the direction of movement is in line with the rear hub and not with the BB.

[Bmblbzzz]

So you're thinking of fitting smaller wheels in order to lower the BB and thus the seatpost, in order to fit this sprung seatpost. What I don't follow is the reason for fitting shorter cranks. Your legs aren't going to shrink... so either you're worried about pedal strike, in which case, is the BB really going to drop 20mm? Or the bike is too big anyway, in which case...

Rim size change: 622-584=38mm / 2 = 19 mm, ergo BB height is reduced by 19mm. Yes, worried about pedal strike.

Okay - I should have done the maths!

[UpWrong]

[youtube]_R2hFZqdiws[/youtube]

[Vantage]

I would probably copy Vantage and saw off the top of the seat tube, and void the warranty:

https://forum.cyclinguk.org/viewtopic.php?t=131583&start=15#p1380339

I'll have to read that, I have no recollection of it whatsoever!

Uh oh, now I'm in trouble!

What I've discovered as a result of that misadventure is that because there's less tube sticking up, the slot in the tube is shorter and so getting the tube to clamp the seatpost requires more force and strains the bolt/nut more. So far no damage but probably not one of my better ideas.

[Jeff31]

How much ground clearance do you need? I feel most bike manufacturers err on the side of having too high a bottom bracket. I am considering putting together a pair of 650B (27.5) wheels for a 700C bike just to overcome this as I don't come close to grounding my pedals. Hoping that being able to get on the bike with less of a stretch, getting more of my foot down whilst still seated and lowering my centre of gravity and profile will make it worth while.
If you do try using smaller wheels, please let us know how you get on.

[slowster]

What I've discovered as a result of that misadventure is that because there's less tube sticking up, the slot in the tube is shorter and so getting the tube to clamp the seatpost requires more force and strains the bolt/nut more. So far no damage but probably not one of my better ideas.

If it ever does become a problem, I would suggest a Surly Constrictor clamp. It uses an M8 bolt (hence the slightly chunky squared profile), which allows more torque, e.g. 9Nm.

https://www.tritoncycles.co.uk/components-c9/seatposts-seat-clamps-c86/constrictor-seat-clamp-p10572

[Bmblbzzz]

How much ground clearance do you need? I feel most bike manufacturers err on the side of having too high a bottom bracket. I am considering putting together a pair of 650B (27.5) wheels for a 700C bike just to overcome this as I don't come close to grounding my pedals. Hoping that being able to get on the bike with less of a stretch, getting more of my foot down whilst still seated and lowering my centre of gravity and profile will make it worth while.
If you do try using smaller wheels, please let us know how you get on.

This was my feeling too, but what sort of surfaces is the OP riding on? If it's a lot of roughstuff, such as rutted bridleways, then ground clearance does become an issue.

[531colin]

What I've discovered as a result of that misadventure is that because there's less tube sticking up, the slot in the tube is shorter and so getting the tube to clamp the seatpost requires more force and strains the bolt/nut more. So far no damage but probably not one of my better ideas.

If it ever does become a problem, I would suggest a Surly Constrictor clamp. It uses an M8 bolt (hence the slightly chunky squared profile), which allows more torque, e.g. 9Nm.

https://www.tritoncycles.co.uk/components-c9/seatposts-seat-clamps-c86/constrictor-seat-clamp-p10572

"No violence please, Bill".....wasn't that Fagin in "Oliver"...?
If the post slips down, something I have used is one of these....
https://www.chainreactioncycles.com/dmr-hinged-clamp/rp-prod745?gs=1&sku=sku4898&istCompanyId=8d42cf00-fc35-44ce-8770-97ae3ffd4c16&istFeedId=c759ee22-6d7f-4501-bd00-f1af47c60490&istItemId=iwxtxlqaa&istBid=t&&utm_source=bing&utm_term=&utm_campaign=PLA+All+Products&utm_medium=base&utm_content=mkwid|a7DHap7O_dc|pcrid|71674500344931|pkw||pmt|be|prd|4898UK&msclkid=e989e594e39112356e75bb7783804d0f
Nominally 28.6 they will nip up on a 27.2 seatpost, maybe by relieving the faces a bit to allow maximum nipping up. I have one araldited to the seatpost of one bike which slips, ....unobtrusive and it works!

[UpWrong]

How much ground clearance do you need? I feel most bike manufacturers err on the side of having too high a bottom bracket. I am considering putting together a pair of 650B (27.5) wheels for a 700C bike just to overcome this as I don't come close to grounding my pedals. Hoping that being able to get on the bike with less of a stretch, getting more of my foot down whilst still seated and lowering my centre of gravity and profile will make it worth while.
If you do try using smaller wheels, please let us know how you get on.

This was my feeling too, but what sort of surfaces is the OP riding on? If it's a lot of roughstuff, such as rutted bridleways, then ground clearance does become an issue.

I want to ride more SUSTRANS routes. The older I get the more I dislike traffic. I'm guessing good clearance might still be helpful. I use 150mm cranks on recumbents so am happy to consider that option.

[Vantage]

"No violence please, Bill".....wasn't that Fagin in "Oliver"...?

No violence necessary
My saving grace on this mishap was the clever thinking by you chaps at Spa to use a steel threaded insert on the seatpost clamp. No alloy to strip

[531colin]

Those standard type seatpost collars have a bit of a snag; in situations where the bolt is tightened repeatedly (eg test bikes in the shop) the bolt fails by fatigue. There is a bending force on the bolt, and the plane of the bend changes as the bolt turns; the bolt head seats against part of the clamp which cannot always be square to the bolt.
To get my bikes in the car I have to remove the seatpost, and below is my modification. The bolt is bent, but only once, because its the nut which turns; the nut seats on Vee brake pad washers which are angle adjustable. Its an M5 hexagon head bolt with the head re-shaped by grinding so the bolt can't turn in the clamp; the thread is drilled out of the steel insert in the clamp.
IMG_1397 by 531colin, on Flickr
IMG_1399 by 531colin, on Flickr

[531colin]

If its not a rude question, why is a suspension seatpost essential?
I have a bad case of the "princess and the pea delusion" which means I am driven to adjust my saddle height when I change between SPD shoes and SPD boots. The adjustment is less than 5mm, but I just have to do it, I can't leave it and be comfortable. I run about 4 bikes at any one time, and saddle height is adjusted to within 3 millimetres; saddle setback, reach to the bars and bar height are OK plus/minus 5mm. (just as well, as stems come in 10mm increments!).
Cleat placement probably varies a couple of millimetres between different shoes.
I think I would prefer to have a puncture every ride to having my saddle move up and down as I ride!
Off road I find I can ride in contact with the saddle but with no real weight on it (and therefore no jarring), my weight is mainly on the pedals....I am pulling back/up on the bars in order to do this.

Have you tried a parallelogram suspension seat post? I used the Suntour NCX on my Thorn Audax Mk3 - awesome! The theory is that the direction of movement is in line with the rear hub and not with the BB.

From the vid. it looks like the movement approximates to an arc drawn on the BB axle as centre, which I guess would be the least disturbing for pedalling. Very clever, but my question remains, why do you want a suspension seatpost? I'm not being deliberately difficult, its a genuine question because I don't understand. Bit of background; I started club riding in the sixties; racing cyclists wore tight woollen shorts with a chamois leather insert, which you softened with chamois cream, touring cyclists wore any shorts you had with normal underwear. (Or touring shorts which had a double seat; not for comfort, but so they didn't wear out!) Everybody rode leather saddles, plastic wasn't invented. I still wear any old shorts with underwear on leather saddles; I've tried padded shorts and padded saddles, and I don't get on with either.
On the previous page somebody is using a suspension seatpost for chip and seal roads. Again I don't get it; when I first toured in Donegal, only A roads were tarred at all, other roads were dirt.

[UpWrong]

Why a suspension seat post? I can't stand on the pedals due to disability and I'm getting more problems with my neck and shoulders. (Too many years riding a Dawes Galaxy on the drops all the time.) So a comfortable sprung saddle and padded shorts helps. Recumbents have the best comfort but have their own drawbacks for off-roading, particularly for those who are shorter than average.

[531colin]

I very rarely get out of the saddle these days, but as above I can ride in contact but with very little weight on the saddle. Maybe if I couldn't or didn't do that I would like some suspension!