carcassonne

I've put last week some 26x1.5 tires on my ActionBent HiRacer. In order to do this I had to file some of the fork and frame. Well, I started out, optimist - if not naive - with a set of 26x1.75. So I filed away at the fork and the lower part of the back frame. A mechanical engineer explained to me later that the upper arm of the back frame is known as a compressor and is a sensible part. But I did not file on those parts. Anyhow, the 1.75 were still not fitting so I exchanged them for 1.5 which immediately fits in the new spaces. The engineer told me that filing away at the protuding tube in the fork does not have any consequence as this is kept for soldering purposes.

All in all, at first I was careful going over bumps but my confidence in the 'new frame' is building up. My first impressions is that it does not affect the speed. The tires I've chosen are Kenda which are made for both street and trail. Slick in the middle with edges on the side. The ride is much. much smoother than with the 26x1 tires given with the bike. Only for that, it's worthwhile to change. Before, the ride was very stiff, almost a displeasure when going over regular bumps found commuting in street/bicycle path loops. The 1.5 tires provides a much smoother ride, inflated at about 60 psi.

I'll post a picture soon.

5port

Wow thats good news! With no mods the tallest I could fit is the Scwalbe Stelvio 1.1 in front with little extra clearance. I like the look and the ride of the Stelvio. Would like to see pix when you can.

carcassonne

Here's a quick picture (taken with cell phone) of the bike with 1.5 tires. Also one with a detail of the Axiom suspended luggage rack which fits nicely and solidely to the bike.

Now, I didn't put that many kms with the new tires so far, perhaps 200. Today I heard some 'spoke noise' when applying torque when going uphill. Perhaps the rear wheel is in need of some adjustement. I've put the dish more the left so that the wheel would be in center of the frame.

Also, I've had - and not yet investigated - a slow air leak in the rear wheel. Maybe a spoke going through the rim ?

Bottom line for now, I can't recommend for the time being doing that, but I have confidence that in the near future the issues will be explained and solved.

BlazingPedals

What is the wheelset on your highracer? If it's a quality wheelset, I'd be more suspicious that the frame was crooked rather than believe the rear wheel was mis-dished. OTOH if the wheel was just something built by CM it could be the wheel, the frame, or both.

Can you ride through a puddle and verify that there's only one wheel track (i.e. the bike is not dog-trotting?)

carcassonne

Hi,

What is the wheelset on your highracer?

It's simply the wheelset given with the bike. The ratchet mechanism of the freehub is one of the loudest I've ever heard in years, if not the loudest ever. I don't need any bell as I just coast and people in distance can notice. Now, this might not speak of the quality of the wheels, but from experience, quietest freehubs equals better components equals better workmanship in building the wheel. But then, I might be wrong.

The noise is definitely a spoke noise. Same noise as when you grab a pair of spokes on a freshly made wheel. Could that somehow be due the frame, eg. the frame would exerce that tension on the wheel ?

... wheel was just something built by CM

What does CM stands for ?

I'll try the puddle test later this week.

Thanks.

Recumbomatic

You can put a MTB fork on there if you want. But it would add significant weight and change the steering geometry. A cheap, used Ebay suspension fork might be interesting.

BlazingPedals

As an Actionbent owner, you should know this, but...

CM stands for China Mascot. What you own is a China Mascot P04 recumbent. I asked about the wheels because you mentioned you had to redish the rear wheel because it sat crooked in the dropouts. Even cheap wheelsets are usually dished correctly, but having a crooked frame can have the same symptom - the wheel doesn't center between the stays. For instance, if the right chainstay is 1/4" longer than the left one, the wheel will cant to the left and the bike will dogtrot with the rear sticking out to the left. Tracking issues will affect stability in corners, so it's something you want to pay attention to.

Recumbomatic

I take it back - since the seat angle is non-adjustable, a suspension fork on this bike might not be a good idea. Raising the BB 4-5 inches and shifing a lot of weight towards the rear on a very short wheelbase could cause problems. I've thought about a suspended highracer, and this is not the right beginning platform.

carcassonne

BP,

CM stands for China Mascot

The name is not completly unknown to me, as I've seen it here and there, but I really thought - as indicated on the headrest - that this was TW-Bents, TW being for Taiwan. Has CM went under and popped up back as TW-Bents ? Or vice-versa ?

For instance, if the right chainstay is 1/4" longer than the left one, ...

I'll check it out, just to be sure, but such a flaw would have been clear from assembly and brake tuning I guess.

Cheers.

carcassonne

R,

Thanks for the comment about a front suspended fork for the HiRacer. I though about fitting a suspended fork, eventually, to the AB HiRacer. Will a suspended fork automatically shift weight to the back ? I mean, wouldn't there be a way to keep it level by sawing off the proper amount of tubing from the fork ? Even if this means to saw a bit more off to have the bike as level as with the regular fork ? If possible, that is.

I guess a suspended fork that is not square with two suspended arms but rather two rigid curved arms with a single suspended stem (a la Cannondale HeadShox) would be a better fit.

Anyhow, I do have a regular MTB suspended fork lying around so I might eventually give it a try. The by-product of this, if it goes well, would be to be able to add front disk brakes. Of which I really don't know if it's a good idea at all that can justify any expense.

Cheers.

BlazingPedals

Hmm... I'm not sure of the whole story, but the pic you posted is the spittin' image of a China Mascot P04 highracer. The TW-Bent offering used to look like this but now their site shows the same model as yours. A bit of corroboration?

Recumbomatic

A suspension fork will raise the headtube by about 3 inches or more. At the end of the boom, the height increase would be 4-5 inches. Not so extreme, since the AB Highracer has a fairly low BB (relative to seat). However, the Highracer seat is already quite reclined. Raising the front will make the seat even more reclined, shifting weight to the back. Less weight on the front usually means lighter, twitchier steering. Also, the 25 inch seat height will increase by 1-2 inches. Will you still be able to reach the ground?

On the other hand, a suspension fork would increase the wheelbase by 1-2 inches. Fatter, heavier tires may very well compensate for twitchier steering. But the extremely reclined seat could be uncomfortable for your neck. Perhaps you could make a bracket to raise the seat angle. Since you already have a suspension fork, try it and let us know what you think.

jeff-o

China Mascot Products Company is the parent company of TW-Bents. There is a whole network of recumbent manufacturers in Taiwan related to CM and TW that build and trade various components with each other. That's why TW's designs are so similar to RecumbentUSA, for example.

5port

Pix are good enough to get the idea. As a fellow AB HR owner I would like to know the name of the company that makes the rack you are using.

Since you are using the stock low spoke count wheels I would be careful how wide a tire you put on them. As you force the sidewalls apart on the rim you affect how the spokes seat in the rim. This could account for the noise.

Running at only 60 psi did the top end suffer? Still able to pull 27mph on the flats? Just curious.

As for the ride I run the stelvios at 105 psi and found that a good compromise but I never take it off road. All in all it looks good but I would go for heavier rims. Low spoke count rims are not made for dirt trails esp with oversize tires.

carcassonne

Sport,

> Pix are good enough to get the idea. As a fellow AB HR owner I
> would like to know the name of the company that makes the rack
> you are using.

It's Axiom, from British Colombia. They've been around for quite a long time. Direct link to this suspended rack:

https://www.axiomgear.com/product/rac...uct.php?id=137

> Since you are using the stock low spoke count wheels I would be
> careful how wide a tire you put on them. As you force the
> sidewalls apart on the rim you affect how the spokes seat in
> the rim. This could account for the noise.

Thanks for the comment. I'm considering building a set of wheels. I did, quite some time ago, following Jobst Brandt's
book. I appreciated the wheels I've built then as they were very reliable. I'd like to try it again.

> Running at only 60 psi did the top end suffer? Still able to pull
> 27mph on the flats? Just curious.

I haven't hit 40 kmh with these new wheels. Indeed. I did not try that much too, but just the notion of having to try means
that there's a performance loss. Which I reckon. Makes me dream of a fully suspended Optima Condor. On the other hand, when
these tires will be in need of change, I'll take more time to select a pair that would go along with the wheels I would,
hopefully, have built. I'd still want wide tires, though. Maybe then I could use the original AB wheels with the 1 inch wide
tires as replacement for road rides.

> As for the ride I run the stelvios at 105 psi and found that a
> good compromise but I never take it off road. All in all it
> looks good but I would go for heavier rims. Low spoke count
> rims are not made for dirt trails esp with oversize tires.

I'll take that into account. Think I'll build a regular spoke-count wheel. My Cannondale has a set of 2.5 wide that weights less than these, so I can certainly figure it out.

That's a far shot, but do you if there's any way to add suspension to the AB HiRacer ? I'm asking at the purely
technical level like would it be possible to fit disc brakes at the back to start with ? There's some kind of a mount with two
holes there, I'm puzzled as to what is it for. Or maybe it is plainly not possible to fit disc brakes in that frame.

Cheers.

Recumbomatic

That mount is for putting on a kickstand on the bike.

carcassonne

Yep, forgot about that one. Must be somewhere in my parts bag.